AFX Slot Car Lap Counter Circuit Diagram

Description

AFX slot car sets are very enjoyable but you can increase the fun with a lap counter. This circuit will count from 00 to 99, with independent counters for each track.

The sensing device used is a Hall effect sensor (UGN3503; available from Dick Smith Electronics). One of these sensors is glued under a section of each track (printed side up); between the slot and one of the track rails is the best spot. In this position, it will allow the ground effects magnets on the cars to pass over them.

The sensor will provide a voltage of about 3V when a car passes over it and about 2V without a magnetic field.

Circuit Diagram

Both counter circuits are identical, with dual op amp IC5 handling the signals from both sensors. IC5a and IC5b are wired as comparators, with a 2.5V reference derived from zener diode ZD1 via the 10kΩ and 12kΩ resistors.

Each time the output of IC5a goes high it clocks IC1a, a 4518 BCD counter. NAND gates IC2a & IC2b provide a carry out to the other half of IC1 for a 2-digit display. More counters may be cascaded this way to provide extra digits. The BCD outputs of IC1 drive 7-segment decoders IC3 & IC4 which drive common cathode LED displays.

Pushbutton S1 resets the counters to 00 for both tracks for the start of a new race.

Source - http://www.siliconchip.com.au/cms/A_30372/article.html

 Placid Talia,
Oakleigh, Vic.

10:21 0 comments

Song Number Display Circuit Diagram

Circuit Diagram

Description

Here’s a circuit to display the song number in an audio system for quick reference to songs. It also serves the purpose of an extra visual indicator in modern audio systems.When the power is switched on, the power-on-reset circuit comprising 3.3k resistor R20 and 1µF, 25V capacitor C6 resets the counters, showing ‘00’ in the display. One can also reset the display to zero at any time by pressing reset switch S1.

When the first song starts playing, the output pins of IC1 (KA2281) go low and capacitor C5 starts charging. This forward biases transistor T1 and hence the input to IC3 at pin 1 goes to high state. As a result, the output of the counter goes to the next state, showing 01 on the display. The counter remains in this state until the song is completed.During the time gap before the next song starts playing, capacitor C5 discharges. After discharging of capacitor C5, the input to IC3 becomes low again. When the song starts, the process described above is repeated and the display shows 02. You can adjust VR3 to change the time gap setting. This must be set such that the circuit doesn’t respond to short gaps, if any, within a song and responds only to long gaps between different songs.Transistor T2 helps in gap-delay adjustment.

The intensity of LED11 diminishes when a song is completed and the counter is ready to accept the next pulse.Connect the input to the preamp output or equaliser output of the audio system. Adjust VR1 and VR2 to get the correct audio-level indication. If you are already using KA2281 for audio-level indication, just connect diodes D1 and D2 as shown in this circuit.Note that the counter counts the songs by detecting the gaps. Therefore any long gap within a song may cause false triggering and the display will also be incremented. However, as this is very unlikely to happen, the circuit shows the correct song number almost all the time.

Source - http://www.way2project.in/projects/2011/04/song-number-display/

08:47 0 comments

Parallel Phone Tap Circuit Diagram

Circuit Diagram

Description

In a recent article, I discussed the difference between parallel and series telephone taps. In this article, I present a very simple and reliable parallel phone tap circuit useful for recording telephone conversations onto a tape recorder.

When installing a telephone tap, its advisable not to cut the telephone line in anyway. Cutting the telephone line for any time is detectable, and therefore series devices can be detected in this way. Parallel devices can be installed without cutting any telephone wires, and is thus harder to detect.

The diagram shows a simple circuit using just 6 very cheap and common components. To build the circuit, you will need some Veroboard or prototype board (whatever you favourite is), some wire, and a 3.5mm plug that will connect to your tape recorder’s microphone input socket. I have left it to the reader to work this bit out, as its very simple to do but quite awkward to explain!
 
Source:http://www.spyreview.co.uk/2006/10/08/parallel-phone-tap-circuit-diagram/

09:38 0 comments

Digital TTL Voltage Testing Meter Circuit Diagram

Description

Free circuit dot com presents the digital tester circuit,this circuit is checking voltage in TTL with display by 7 segment.

I think the circuit will be using for you apply to your electronic projects.
The function of circuit is sorting TTL voltage with resister to drive transister BC547B after that it will be drive IC model 74SL00 to turn on each segment of 7 segment display.

Part List
IC 74LS00 1 pcs.
T1-T3 BC547B 3 pcs.
R1,R2,R5,R6 10K ohms
R3 47K ohms
R4 8.2 K ohms
7 segment 1 pcs.

Source -http://www.free-circuit.com/2012/11/14/digital-ttl-voltage-testing-meter-circuit/

10:23 0 comments

Automotive 12V to +-20V converter (for audio amplifier) Circuit Diagram

The limitation of car supply voltage (12V) forces to convert the voltages to higher in order to power audio amplifiers.

In fact the max audio power x speaker (with 4 ohm impedance) using 12V is (Vsupply+ - Vsupply-)^2/(8*impedance) 12^2/32 = 4.5Watts per channel, that is laughable...

For powering correctly an amplifier the best is to use a symmetric supply with a high voltage differential. for example +20 - -20 = 40Volts
in fact
40^2/32 = 50 Watts per channel that is respectable.

This supply is intended for two channels with 50W max each (of course it depends on the amplifier used). Though it can be easily scaled up or the voltages changed to obtain different values.

Circuit Diagram

Overview - How it works

It is a classic push-pull design , taking care to obtain best symmetry (to avoid flux walking). Keep in mind that this circuit will adsorb many amperes (around 10A) so take care to reinforce power tracks with lots of solder and use heavy wires from the battery or the voltage will drop too much at the input.

The transformer must be designed to reduce skin effect, it can be done using several insulated magnet wire single wires soldered together but conducting separately. The regulation is done both by the transformer turn ratio and varying the duty cycle. In my case i used 5+5 , 10+10 turns obtaining a step up ratio of 2 (12->24) and downregulating the voltage to 20 via duty cycle dynamic adjust performed by the PWM controller TL494.

The step-up ratio has to be a little higher to overcome diode losses, winding resistance and so on and input voltage drop due to wire resistance from battery to converter.

Transformer design

The transformer must be of correct size in order to carry the power needed, on the net there are many charts showing the power in function of frequency and core size for a given topology. My transformer size is 33.5 mm lenght, 30.0 height and 13mm width with a cross section area of 1,25cm^2, good for powers around 150W at 50khz.

The windings , especially the primary must be heavy gauged, but instead of using a single wire it is better to use
multiple wires in parallel each insulated from the other except at the ends. This will reduce resistance increase due to skin effect. The primary and secondary windings are centertapped, this means that you have to wind 5 turns, centertap and 5 windings again. The same goes for the secondary, 10 turns, centertap and 10 turns again.

The important thing is that the transformer MUST not have air gaps or the leakage inductance will throw spikes on the switches overheating them and giving a voltage higher than expected by turn ratio prediction, so if your voltage output (at fully duty cycle) is higher than Vin*N2/N1 - Vdrop diode, your transformer has gap (of course permit me saying you that you are BLIND if you miss it), and this is accompanied with a drastical efficiency reduction. Use non-gapped E cores or toroids (ferrite).

Output diodes, capacitors and filter inductor

For rectification i preferred to use shottky diodes since they have low forward voltage drop, and are incredibly fast.
I used the cheap 1N5822, the best alternative for low voltage converters (3A for current capability).

The output capacitors are 4700uF 25V, not very big, since at high frequency the voltage ripple is most due to internal cap ESR fortunately general purpose lytics have enough low esr for a small ripple (some tens of millivolts). Also at high duty cycle they are feed almost with pure DC, giving small ripple. The filter inductor on the secondary centertap furter increases the ripple and helps the regulation in asymmetrical transients


Power switch and driving

I used d2pak 70V 80A 0.004 ohms ultrafets (Fairchind semiconductor), very expensive and hard to find. In principle any fet will work, but the lower the on-resistance, the lower the on-state conduction losses, the lower the heat produced on the fets, the higher efficiency and smaller the heatsinks needed. With this fets i am able to run the fets with small heatsinks and without fan at full rated power (100W) with an efficiency of 82% and perceptible heating and with small heating at 120W (some degrees) (the core starts to saturate and the efficiency is a bit lower, around 75%)

Try to use the lowest resistance mosfet you can put your dirty hand :-) on or the efficiency will be lower than rated and you will need even a small fan. The fet driver i used is the TPS2811P, from Texas instruments, rated for 2A peak and 200ns. Is important that the gate drive is optimized for minimal inductance or the switching losses will be higher and you risk noise coupling from other sources. Personally i think that twisted pair wires (gate and ground/source) are the best to keep the inductance small. Place the gate drive resistor near the Mosfet, not near the IC.

Controller

I used the trusty TL494 PWM controller with frequency set at around 40-60 Khz adjustable with a potentiometer. I also implemented the soft start (to reduce powerup transients). The adjust potentiometer (feedback) must be set to obtain the desired voltage. The output signals is designed with two pull-up resistors on the collector of the PWM chip output transistor pulling them to ground each cycle alternatively. This signal is sent to the dual inverting MOSFET driver (TPS2811P) obtaining the correct waveform.

Power and filtering

How i said before the power tracks must be heavy gauged or you will scarify regulation (since it depends of transformer step up ratio and input voltage) and efficiency too. Don't forget to place a 10A (or 15A) fuse on the input because the car batteries can supply very high currents in case of shorts and this will save you face from a mosfet explosion in case of failture or short, remember to place a fuse also on the battery side to increase the safety (accidental shorts->fire, battery explosion, firemen, police and lawyers around). Input filtering is important, use at least 20000uF 16V in capacitors, a filter inductor would be useful too (heavygauged) but i decided to leave it..

Final considerations

This supply given me up to 85% efficiency (sometimes even 90% at some loads) with an input of 12V because i observed all these tricks to keep it functional and efficient. An o-scope would be useful, to watch the ripple and gate signals (watching for overshoots), but if you follow these guidelines you will avoid these problems.

The cross regulation is good but keep in mind that only the positive output is fully regulated, and the negative only follows it. Place a small load between the negative rail and ground (a 3mm led with a 4.7Kohm resistor) to avoid the negative rail getting lower then -20V. If the load is asymmetric you can have two cases:

-More load on positive rail-> no problems, the negative rail can go lower than -20V, but it is not a real issue for an audio amplifier.
-More load on negative rail-> voltage drop on negative rail (to ground) especially if the load is only on the negative rail.

Fortunately audio amplifiers are quite symmetrical as a load, and the output filter inductor/capacitors helps to maintain the regulation good during asymmetrical transients (Basses)

ATTENTION Keep in mind that THIS IS NOT A PROJECT FOR A BEGINNER, IT CAN BE VERY DANGEROUS IN CASE OF PROBLEMS, NEVER BRIDGE, BYPASS OR AVOID FUSES THESE WILL SAVE YOUR BACK FROM FIRE RISK.

FOR FIRST TESTING USE A SMALL 12V power supply and use resistors as load monitoring switches heat and current consumption (and output) and try to determine efficiency, if it is higher then 70-75% you are set, it is enough. Adjust the frequency for best compromise between power and switching losses, skin effect and hysteresis losses


Bill Of Materials
=================
Design: 12V to 20V 100W DC-DC conv
Doc. no.: 1
Revision: 3
Author: Jonathan Filippi
Created: 29/04/05
Modified: 18/05/05

Parts List
--- --------- -----
Resistors
---------
2   R1,R2 = 10
4   R3,R4,R6,R7 = 1k
1   R5 = 22k
1   R8 = 4.7k
1   R9 = 100k

Capacitors
----------
2   C1,C2 = 10000uF
2   C3,C6 = 47u
1   C4 = 10u
3   C5,C7,C14 = 100n
2   C8,C9 = 4700u
1   C12 = 1n
1   C13 = 2.2u

Integrated Circuits
-------------------
1   U1 = TL494
1   U2 = TPS2811P

Transistors
-----------
2 Q1,Q2 = FDB045AN

Diodes
------
4   D1-D4 = 1N5822
1   D5 = 1N4148

Miscellaneous
-------------
1   FU1 = 10A
1   L1 = 10u
1   L2 = FERRITE BEAD
1   RV1 = 2.2k
1   RV2 = 24k
1   T1 = TRAN-3P3S

Source - http://www.electronics-lab.com/projects/automotive/002/index.html
Author: Jonathan Filippi -  jonathan.filippivirgilio.it -www.cool-science.tk

08:48 0 comments

FM Booster Diagram Circuit

Description

A low-cost circuit of an FM booster that can be used to listen programs from distant FM stations clearly. The circuit comprises a common-emitter tuned RF preamplifier wired around VHF/UHF transistor 2SC2570 ( C2570).
This FM booster circuit is constructed using few common components ( not require some special components ) and provide a very good gain .
To calibrate this circuit you need to adjust input/output trimmers (VC1/VC2) for maximum gain.
Input coil L1 consists of four turns of 20SWG enamelled copper wire (slightly space wound) over 5mm diameter former.

It is tapped at the first turn from ground lead side. Coil L2 is similar to L1, but has only three turns.
Both of the trimmers are 22pF value .This FM radio signal booster needs to be powered by a 12 volts DC power supply .

Circuit Diagram

Source - http://www.electroniq.net/radio-frequency/fm-booster-schematic-circuit.html

12:19 0 comments

LM386 Audio Amp IC Internal Circuit Diagram

LM386 had been used for long time as an audio amplifier IC for low power applications. The schematic herein shows the LM386 internal circuit schematic.

 LM386 can be seen in three flavors, there are LM386-1, LM386-2 and LM386-3. Each of device provides 0.3W, 0.5W and 0.7W respectively.

Source - http://www.hqew.net/circuit-diagram/LM386-Audio-Amp-IC-Internal-Circuit-Schematic_5831.html

09:55 0 comments

A Bedside Lamp Timer Circuit Diagram

Description 

 The purpose of this circuit is to power a lamp or other appliance for a given time (30 minutes in this case), and then to turn it off. It is useful when reading at bed by night, turning off the bedside lamp automatically in case the reader falls asleep... After turn-on by P1 pushbutton, the LED illuminates for around 25 minutes, but then it starts to blink for two minutes, stops blinking for two minutes and blinks for another two just before switching the lamp off, thus signaling that the on-time is ending. If the user want to prolong the reading, he/she can earn another half-hour of light by pushing on P1. Turning-off the lamp at user's ease is obtained by pushing on P2. 

Circuit diagram: 

Parts:

• R1 = 1K
• R2 = 4K7
• R3 = 10M
• R4 = 1M
• R5 = 10K
• C1 = 470µF-25V
• C2-C4100nF-63V
• C1 = 470µF-25V
• C2-C4 = 100nF-63V
• D1-D4 = 1N4002
• D5 = 5mm. Red LED
• IC1 = CD4012
• IC2 = CD4060
• Q1 = BC328
• Q2 = BC547
• P1,P2 = SPST Pushbuttons
• T1 = 9+9 Volt Secondary 1VA Mains transformer
• RL1 = 10.5V 470 Ohm Relay with SPDT 2A 220V switch
• PL1 = Male Mains plug
• SK1 = Female Mains socket

Circuit operation: 

Q1 and Q2 form an ALL-ON ALL-OFF circuit that in the off state draws no significant current. P1 starts the circuit, the relay is turned on and the two ICs are powered. The lamp is powered by the relay switch, and IC2 is reset with a positive voltage at pin 12. IC2 starts oscillating at a frequency set by R4 and C4. With the values shown, pin 3 goes high after around 30 minutes, turning off the circuit via C3. During the c6 minutes preceding turn-off.

The LED does a blinking action by connections of IC1 to pins 1, 2 & 15 of IC2. Blinking frequency is provided by IC2 oscillator at pin 9. The two gates of IC1 are wired in parallel to source more current. If required, a piezo sounder can be connected to pins 1 & 14 of IC1. Obviously, timings can be varied changing C4 and/or R4 values.

Source - http://www.extremecircuits.net/2009/12/bedside-lamp-timer-circuit-schematic.html

15:05 0 comments

Rain Alarm Circuit Diagram

Circuit Diagram

GIVES BEEP WHEN WATER IS IN CONTACT WITH THE WIRE

Description

     Water is a conductor of electricity. When water is in contact with the probe then there is a flow of current which reaches to the base of Q1. Transistor Q1 is a NPN transistor which conducts. With the conduction of Q1 electron reaches to Q2 which is a PNP transistor .Q2 also conducts and current flows through the speaker. In a speaker there is inductive coil which causes motion in one direction and also produce induce current which is in opposite direction to the flow of current this induce current in the form of pulse flows through a capacitor, resistance and switches off Q1 and relax .this process repeats again and again till probe is in contact with water or we can say there is a oscillation in the circuit thus speaker diaphragm vibrates and gives a tone. Frequency of the circuit depends on the value of Speaker Coil impendence, Capacitor and Resistance Value.

Source http://circuiteasy.com/rain-alarm/

10:48 0 comments

Simple FM Receiver Circuit Diagram

Description

This is the most simple fm receiver with good performances that works great even if the sensitivity is not too high. The working principle of this fm receiver may seem a little unusual. It is made of an oscillator (T2 and T3) that is synchronized with the received frequency of T1.
This transistor works as a broadband preamplifier in VHF range.

 The oscillator is adjusted between 87 … 108 MHz with C5. Because of the synchronization, the oscillator output will have the same frequency deviation as the received signal from the fm antenna. This deviations are caused by the broadcasted audio informations. The frequency modulated signal show up on P1 + R5. Low pass filter R6/C6 extracts the audio signal and then is amplifier by T4 … T6 and transmitted at the output through C9 capacitor.

Circuit Diagram

The coil details are presented in the fm receiver circuit diagram. The radio receiver is adjusted on different stations with the help of C5. P1 potentiometer is adjusted untill the best reception is obtained. If we attach an audio amplifier and a speaker then this fm receiver can be made very compact as a pocket radio.

09:37 2 comments

300W Subwoofer Amplifier Circuit Diagram

Description

This is an amplifier circuit that is formed from a transistor amplifier miraculous. This circuit is used in the speaker subwoofer with 300W maximum power on each side. To apply it, can be used in the room that is not too large, like the car. And the voltage needed between 25 to 42 Volt DC.

Circuit Diagram 

Source-http://gambarskemarangkaian.blogspot.in/2011/04/300w-subwoofer-amplifier-schematic.html

09:56 0 comments

Frost Alarm Simple Circuit Diagram

Circuit Diagram

Notes:

The thermistor used has a resistance of 15k at 25 degrees and 45k at 0 degrees celsius. A suitable bead type thermistor is found in the Maplin catalogue. The 100k pot allows this circuit to trigger over a wide range of temperatures. A slight amount of hysteresis is provided by inclusion of the 270k resistor. This prevents relay chatter when temperature is near the switching threshold of this circuit.

Source - http://www.hobbyprojects.com/quick_circuits_reference/circuits/frost_alarm_circuit.html

08:40 0 comments

High Power Audio Amplifier 2800W Circuit Schematic Diagram

Description

Mono high power amplifier is actually a powerful 1400 W, but if this hihgh power amplifier circuit is doubled and you want to create stereo, high power amplifier the necessary components and pcb requires two-fold. So if the stereo high power amplifier 2 X 1400W. Schematic Circuit diagram is still less by looking at the circuit that was so below, the finished circuit has been added with a gains using JRC4558 IC by the two and the picture ic where it can be seen below. For circuit buffers, drivers, and booster use multiple transistors and other components (can be seen listed component). And high power amplifier project that is so below is just part of the buffer and driver while the booster has not been made​​. For additional transistors in the booster or high power amplifier end scheme can be found Booster output power amplifier.

Circuit Schematic Diagram :

Part List :

R1_____560Ω
R2_____100Ω
R3_____2K2Ω
R4_____560Ω
R5_____1Ω
R6_____27KΩ
R7_____10KΩ
R8_____100Ω
R9_____100Ω
R10____100Ω
R11____12KΩ
R12____100Ω
R13____100Ω
R14____100Ω
R15____27KΩ
R16____2K2Ω
R17____560Ω
R18____100Ω
R19____10KΩ
R20____330Ω
R21____47Ω 2W
R22____56Ω
R23____2K2Ω
R24____22Ω
R25____56Ω
R26____180Ω
R27____500-1KΩ Trim
R28____560Ω
R29____56Ω
R30____56Ω
R31____22Ω 1W
R32____5Ω6 2W
R33____10Ω
R34____180Ω
R35____100Ω
R36____22Ω 2W
R37____180Ω
R38____56Ω
R39____47Ω 2W
R40____5Ω6 2W
R41____10Ω
R42____10Ω
R43____10Ω
R45____10Ω
R46____0.22Ω 5W
R47____0.22Ω 5W
R48____0.22Ω 5W
R49____0.22Ω 5W
R50____10Ω 5W
C1_____1цF
C2_____1.5nF
C3_____0.1цF 250-275V
C4_____0.1цF 250-275VC5_____100nF
C6_____100цF 50V
C7_____39pF
C8_____330pF
C9_____330pF
C10____330pF
C11____47nF 250-275V
C12____220nF 250-275V
T1_____MJE340
T2_____2N5551 / C2240
T3_____2N5551 / C2240
T4_____2N5551 / C2240
T5_____2N5551 / C2240
T6_____2N5401 / BF423
T7_____2N5401 / BF423
T8_____2N5401 / BF423
T9_____2N5401 / BF423
T10____MJE350
T11____B1186
T12____TIP127
T13____D1763
T14____D1763
T15____B1186
T16____C5198
T17____A1941
T18____2SC2922 / MJ15024G
T19____2SC2922 / MJ15024G
T20____2SA1216 / MJ15025G
T21____2SA1216 / MJ15025G

 This installation include gain JRC4558

This is pcb design

 Installation with booster

 PCB design by SIGMA-4 Madiun ©

Source -  http://ampcircuitschematic.blogspot.in/2011/03/2800w-high-power-audio-amplifier.html#.UKe63JFJG9u

08:36 0 comments

Tuned Radio Frequency (TRF) Receiver Circuit Diagram

Description

Superheterodyne receivers have been mass-produced since around 1924, but for reasons of cost did not become successful until the 1930s. Before the second world war other, simpler receiver technologies such as the TRF receiver and the regenerative receiver were still widespread. The circuit described here is based on the old technology, but brought up-to-date a The most important part of the circuit is the input stage, where positive feedback is used to achieve good sensitivity and selectivity. The first stage is adjusted so that it is not quite at the point of oscillation. This increases the gain and the selectivity, giving a narrow bandwidth.

To achieve this, the potentiometer connected to the drain of the FET must be adjusted very carefully: optimal performance of the receiver depends on its setting. In ideal conditions several strong stations should be obtainable during the day using a 50 cm antenna. At night, several times this number should be obtainable. The frequency range of the receiver runs from 6 MHz to 8 MHz. This range covers the 49 m and the 41 m shortwave bands in which many European stations broadcast. Not bad for such a simple circuit! The circuit employs six transistors. The first stage is a selective amplifier, followed by a transistor detector. Two low-frequency amplifier stages complete the circuit.

Circuit diagram:

The final stage is a push-pull arrangement for optimal drive of the low-impedance loudspeaker. This circuit arrangement is sometimes called a ‘1V2 receiver’ (one preamplifier, one detector and two audio-frequency stages). Setting-up is straightforward. Adjust P1 until the point is reached where the circuit starts to oscillate: a whistle will be heard from the loudspeaker. Now back off the potentiometer until the whistle stops. The receiver can now be tuned to a broadcaster. Occasional further adjustment of the potentiometer may be required after the station is tuned in. The receiver operates from a supply voltage of between 5 V and 12 V and uses very little current. A 9 V PP3 (6F22) battery should give a very long life.

 Author: Gert Baars

 Source - http://www.extremecircuits.net/2010/06/tuned-radio-frequency-trf-receiver_21.html

09:55 0 comments

Sound Controlled Filp Flop Circuit Diagram

Description

Described here is a very inexpensive solution to many phono-controlled applications like remote switching on, for instance, or activating a camera, tape recorder, burglar alarms, toys, etc. The circuit given here employs a condenser microphone as the pick-up. A two-stage amplifier built around a quad op-amp IC LM324 offers a good gain to enable sound pick-up upto four metres. The third op-amp is configured as a level detector whose non-inverting terminal is fed with the amplified and filtered signal available at the output of the second op-amp. The inverting input of the third op-amp is given a reference voltage from a potential divider consisting of a 10k resistor and a 4.7k preset. The 100-ohm resistance in series with the potential divider ensures against the mis-triggering of the circuit by noise. Thus by adjusting the preset one can control the sensitivity (threshold) of the circuit. The sensitivity control thus helps in rejecting any external unwanted sounds which may be picked up by the amplifier. The output of the level detector are square pulses which are used to trigger a flip-flop. The 100mF capacitor connected across the supply also helps in bypassing noise.

Circut Diagram

A well regulated supply is recommended for proper functioning of the circuit because an unregulated supply can cause noise pulses to appear in the supply rails when the circuit changes-over state (especially when a load is connected to the circuit). These pulses can be picked up by the sensitive amplifier which will cause the circuit to again switch-over states, resulting into motor-boating noise. Since the circuit operates at 4.5V, it can be easily incorporated in digital circuits. Fig. (b) shows how the circuit can be employed to control the direction of a DC motor. The circuit employs four npn transistors. Transistors T1 and T4 have their bases tied together and they switch-on simultaneously when Q output is logic 1. Similarly T2 and T3 conduct when Q output is logic 1. Thus current through the motor changes direction when the flip-flop toggles. Filters connected in the circuit and tuned to different bands of audio frequencies will enable the same circuit to control more than one device. For instance, a high frequency sound (such as whistle) can switch on device 1 and a low frequency sound (such as clapping) can control device 2.
Source -http://www.electronic-circuits-diagrams.com/audioimages/audiockt9.shtml

09:46 0 comments

Battery Tester Circuit Schematic

Description 

 Is the battery empty, or is there something wrong with the device? That’s always a difficult question when your walkman or some other battery-powered device appears to be dead when you switch it on. Before you take it to the shop for servicing, the first thing you should do is to test the battery or batteries. Of course, this means you need a reliable battery tester, but it also means you can limit the damage to the cost of a battery or two and a one-time investment of time and money in building a suitable tester. 

Circuit diagram:

Many commercial battery testers consist of nothing more than a resistor, a simple little meter and a push-button. Some manufacturers include an even simpler tester with a set of batteries, consisting of a strip of plastic with a layer of some sort of electrically conductive material that changes color when a current grows through it. If you press this strip over the battery between the positive and negative terminals, a fully charged battery will cause a more intense change in color than a partially discharged battery.
Naturally, tests of this sort do not provide especially reliable or accurate results. The idea behind the circuit described here is to load a single battery, a set of batteries connected in series, a rechargeable battery, or even a small button cell with a reasonably constant current and use a separate multimeter or voltmeter module (M1) to check the voltage. A quickly decreasing voltage indicates that the battery or batteries will have to be replaced soon. If a constant-current circuit is used for the load, the current can never too be large and there is no need to make an adjustment for the number of cells.
The constant-current circuit is specially designed to work with a voltage as low as 0.9 V. It’s quite difficult to make a circuit work at even lower voltages with normal transistors. The active constant-current element is transistor T1. The current through it is held constant by comparing the voltage across resistor R1 in its collector path with a relatively constant reference voltage across diode D1. This comparison is provided by differential amplifier T3/T4.
The voltage across diode D1 (a Schottky type) is reasonably constant by nature, but it is also stabilized by using FET T5 as a simple constant-current sink. T5 also limits the current at relatively high voltages (with several batteries in series). The constant voltage across D1 is transferred to resistor R12 by differential amplifier T1/T2, so a constant current grows through R1 from the battery or batteries being tested. R1 has a relatively low resistance, so this current is larger than the current drawn by the rest of the circuit.
The quiescent current, which incidentally is also reasonab constant, is thus negligible. The test current thus remains reasonably constant while the battery or batteries is/are being tested. The maximum battery voltage that the tester can handle is set by T5, and here it is 30 V. To ensure that T1 does not get too warm at high battery voltages, keep the test as short as possible. Use a push-button switch as a test switch so the battery being tested cannot be left under load by accident.

Source http://www.extremecircuits.net/2010/04/battery-tester-circuit-schematic.html

09:58 0 comments

Digital Remote Thermometer Circuit Diagram

Remote sensor sends data via mains supply
Temperature range: 00.0 to 99.9 °C
Transmitter Circuit Diagram:

R1,R3________100K  1/4W Resistors
R2___________47R   1/4W Resistor
R4____________5K   1/2W Trimmer Cermet
R5___________12K   1/4W Resistor
R6___________10K   1/4W Resistor
R7____________6K8  1/4W Resistor
R8,R9_________1K   1/4W Resistors

C1___________220nF  63V Polyester Capacitor
C2____________10nF  63V Polyester Capacitor
C3_____________1µF  63V Polyester Capacitor
C4,C6__________1nF  63V Polyester Capacitors
C5_____________2n2  63V Polyester Capacitor
C7,C8_________47nF 400V Polyester Capacitors
C9__________1000µF  25V Electrolytic Capacitor

D1__________1N4148  75V 150mA Diode
D2,D3_______1N4002 100V 1A Diodes
D4____________5mm. Red LED

IC1___________LM35  Linear temperature sensor IC
IC2__________LM331  Voltage-frequency converter IC
IC3__________78L06  6V 100mA Voltage regulator IC

Q1___________BC238  25V 100mA NPN Transistor
Q2___________BD139  80V 1.5A NPN Transistor

L1___________Primary (Connected to Q2 Collector): 100 turns
             Secondary: 10 turns
             Wire diameter: O.2mm. enameled
             Plastic former with ferrite core. Outer diameter: 4mm. 

T1___________220V Primary, 12+12V Secondary 3VA Mains transformer

PL1__________Male Mains plug & cable

Receiver Circuit Diagram:

Receiver Parts:

R1__________100K   1/4W Resistor
R2____________1K   1/4W Resistor
R3,R4,R6-R8__12K   1/4W Resistors
R5___________47K   1/4W Resistor
R9-R15______470R   1/4W Resistors
R16_________680R   1/4W Resistor

C1,C2_________47nF 400V Polyester Capacitors
C3,C7__________1nF  63V Polyester Capacitors
C4____________10nF  63V Polyester Capacitor
C5,C6,C10____220nF  63V Polyester Capacitors
C8__________1000µF  25V Electrolytic Capacitor
C9___________100pF  63V Ceramic Capacitor

D1,D2,D5____1N4148  75V 150mA Diodes
D4,D4_______1N4002 100V 1A Diodes
D6-D8_______Common-cathode 7-segment LED mini-displays

IC1__________4093   Quad 2 input Schmitt NAND Gate IC
IC2__________4518   Dual BCD Up-Counter IC
IC3__________78L12  12V 100mA Voltage regulator IC
IC4__________4017   Decade Counter with 10 decoded outputs IC
IC5__________4553   Three-digit BCD Counter IC
IC6__________4511   BCD-to-7-Segment Latch/Decoder/Driver IC

Q1___________BC239C 25V 100mA NPN Transistor
Q2-Q4________BC327  45V 800mA PNP Transistors

L1___________Primary (Connected to C1 & C2): 10 turns
             Secondary: 100 turns
             Wire diameter: O.2mm. enameled
             Plastic former with ferrite core. Outer diameter: 4mm. 

T1___________220V Primary, 12+12V Secondary 3VA Mains transformer

PL1__________Male Mains plug & cable

Device purpose: 

 This circuit is intended for precision centigrade temperature measurement, with a transmitter section converting to frequency the sensor's output voltage, which is proportional to the measured temperature. The output frequency bursts are conveyed into the mains supply cables.
The receiver section counts the bursts coming from mains supply and shows the counting on three 7-segment LED displays. The least significant digit displays tenths of degree and then a 00.0 to 99.9 °C range is obtained.
Transmitter-receiver distance can reach hundred meters, provided both units are connected to the mains supply within the control of the same light-meter

Transmitter circuit operation:

 IC1 is a precision centigrade temperature sensor with a linear output of 10mV/°C driving IC2, a voltage-frequency converter. At its output pin (3), an input of 10mV is converted to 100Hz frequency pulses. Thus, for example, a temperature of 20°C is converted by IC1 to 200mV and then by IC2 to 2KHz. Q1 is the driver of the power output transistor Q2, coupled to the mains supply by L1 and C7, C8.

Receiver circuit operation: 
 The frequency pulses coming from mains supply and safely insulated by C1, C2 & L1 are amplified by Q1; diodes D1 and D2 limiting peaks at its input. Pulses are filtered by C5, squared by IC1B, divided by 10 in IC2B and sent for the final count to the clock input of IC5.
IC4 is the time-base generator: it provides reset pulses for IC1B and IC5 and enables latches and gate-time of IC5 at 1Hz frequency. It is driven by a 5Hz square wave obtained from 50Hz mains frequency picked-up from T1 secondary, squared by IC1C and divided by 10 in IC2A.
IC5 drives the displays' cathodes via Q2, Q3 & Q4 at a multiplexing rate frequency fixed by C7. It drives also the 3 displays' paralleled anodes via the BCD-to-7 segment decoder IC6.
Summing up, input pulses from mains supply at, say, 2KHz frequency, are divided by 10 and displayed as 20.0°C.

Notes:

• D6 is the Most Significant Digit and D8 is the Least Significant Digit.
• R16 is connected to the Dot anode of D7 to illuminate permanently the decimal point.
• Set the ferrite cores of both inductors for maximum output (best measured with an oscilloscope, but not critical).
• Set trimmer R4 in the transmitter to obtain a frequency of 5KHz at pin 3 of IC2 with an input of 0.5Vcc at pin 7 (a digital frequency meter is required).
• More simple setup: place a thermometer close to IC1 sensor, then set R4 to obtain the same reading of the thermometer in the receiver's display.
• Keep the sensor (IC1) well away from heating sources (e.g. Mains Transformer T1).
• Linearity is very good.
• Warning! Both circuits are connected to 230Vac mains, then some parts in the circuit boards are subjected to lethal potential! Avoid touching the circuits when plugged and enclose them in plastic boxes.

Source -  http://redcircuits.com/Page11.htm

09:21 0 comments

Cuckoo Sound Generator Circuit Diagram

Description 

This circuit generates a two-tone effect very much alike the cuckoo song. It can be used for door-bells or other purposes thanks to a built-in audio amplifier and loudspeaker. Used as a sound effect generator it can be connected to external amplifiers, tape recorders etc. In this case, the built-in audio amplifier and loudspeaker may be omitted and the output taken across C8 and ground. There are two options: free running, when SW1 is left open, and one-shot, when SW1 is closed. In this case a two-tone cuckoo song will be generated at each P1 pressing.
Circuit diagram:

Parts:

• R1,R5___________1K 1/4W Resistors
• R2_____________50K 1/2W Trimmer Cermet
• R3______________8K2 1/4W Resistor
• R4_____________82K 1/4W Resistor
• R6______________1M 1/4W Resistor
• R7,R17,R20,R21_22K 1/4W Resistors
• R8,R10,R11,R19_10K 1/4W Resistors
• R9____________150K 1/4W Resistor
• R12_____________4K7 1/4W Resistor
• R13___________100K 1/4W Resistor
• R14___________220R 1/4W Resistor
• R15,R22________20K 1/2W Trimmers Cermet
• R16____________10R 1/4W Resistor
• R18___________200K 1/2W Trimmer Cermet
• C1,C11_________47nF 63V Polyester or Ceramic Capacitors
• C2,C10,C12____220µF 25V Electrolytic Capacitors
• C3____________220nF 63V Polyester or Ceramic Capacitor
• C4_____________22nF 63V Polyester or Ceramic Capacitor
• C5,C6,C8,C9___100nF 63V Polyester or Ceramic Capacitors
• C7,C13,C14_____10µF 63V Electrolytic Capacitors
• D1,D2,D3,D6__1N4148 75V 150mA Diodes
• D4,D5_________BAT46 100V 150mA Schottky-barrier Diodes
• Q1,Q2_________BC547 45V 100mA NPN Transistors
• IC1____________7555 or TS555CN CMos Timer IC
• IC2____________4093 Quad 2 input Schmitt NAND Gate IC
• IC3____________4017 Decade counter with 10 decoded outputs IC
• IC4___________LM386 Audio power amplifier IC
• P1_____________SPST Pushbutton
• SW1____________SPST Switch
• SPKR___________8 Ohm Loudspeaker 

Circuit operation:

IC1 is wired as a square wave generator and produces both tones of the cuckoo song. The frequency of the higher one (667Hz) is set by means of Trimmer R2. When IC2D output goes low, a further Trimmer (R22) is added to IC1 timing components via D6, and the lower tone (545Hz) is generated. To imitate closely the cuckoo song, the square wave output of IC1 is converted to a quasi-sinusoidal wave form by R3, R4, C3 and C4, then mixed with the white noise generated by Q1, R6.

Q2 has two purposes: it mixes the two incoming signals and gates the resulting tone, shaping its attack and decay behavior by means of the parts wired around its Emitter. IC4 is the audio power amplifier driving the speaker and R15 is the volume control. The various sound and pause timings for the circuit are provided by the clock generator IC2A driving the decade counter IC3. Some output pins of this IC are gated by IC2C, IC2D and related components to drive appropriately the sound generator and the sound gate.

When SW1 is left open the circuit operates in the free-running mode and the cuckoo song is generated continuously. When SW1 is closed, the circuit generates two tones then stops, because a high state appears at the last output pin (#11) of the decade counter IC: therefore the count is inhibited by means of D1 feeding pin #13. The circuit is reset by a positive pulse at pin #15 of IC3 when P1 is pressed. 

Setup: 
Best results will be obtained if the two tones frequencies are set precisely, i.e. 667Hz for the first tone and 545Hz for the second: in musical terms this interval is called a Minor Third. Obviously a digital frequency counter, if available, would be the best tool to setup R2 and R22, but you can use a musical instrument, e.g. a piano or guitar, tuning-up the notes accurately by ear.

• Disconnect temporarily R22 from D6 anode.
• Connect the digital frequency counter to pin 3 of IC1.
• Adjust R2 in order to read 667Hz on the display.
• Connect R22 to negative ground and adjust it to read 545Hz on the display.
• Restore R22 - D6 connection. 

Tuning by ear:

• Disconnect temporarily R22 from D6 anode.
• Disconnect C8 from Q2 Collector and connect it to R4, C4 and C5 junction.
• Adjust R2 in order that the tone generated by the loudspeaker is at the same pitch of the reference note generated by your musical instrument. This reference note will be the E written on the stave in the fourth space when using the treble clef.
• Connect R22 to negative ground and adjust it in order that the tone generated by the loudspeaker is at the same pitch of the reference note generated by your musical instrument. This second reference note will be the C-sharp written on the stave in the third space when using the treble clef.
• Restore R22 - D6 and C8 to Q2 Collector connections.

Notes:

• The master clock can be adjusted by means of R18.
• The percentage of hiss and sound in the mixing circuit, setting the tone character, can be varied changing R8 and R7 values respectively.
• Any kind of dc voltage supply in the 12 - 15V range can be used, but please note that supply voltages below 12V will prevent operation of the white noise generator.
• An amusing application of this circuit is to use a photo-resistor in place of P1, then placing the unit near the flashing lamps of your Christmas tree. A sweet cuckoo song will be heard each time the lamp chosen will illuminate. 

Source - http://www.extremecircuits.net/2010/01/cuckoo-sound-generator-circuit.html

10:42 0 comments

Mains Frequency Monitor Circuit Diagram

Description

Here is a simple frequency counter designed to monitor the 240VAC mains supply. It as a frequency range of 0-999Hz, so it could also be used with 400Hz equipment. Standard TTL/CMOS logic is employed for the counters and display drivers, while an ELM446 (IC1) generates accurate 1Hz pulses for gating. This device utilizes a 3.579545MHz crystal for its timebase, as commonly found in TV and video circuits and even on old PC motherboards.

Circuit diagram:

Mains Frequency Monitor Circuit Diagram

Source http://www.extremecircuits.net/2010/06/mains-frequency-monitor_01.html

Author : Silicon Chip Electronics Magazine

11:31 0 comments

Picoammeter Circuit With 4 Ranges Diagram

Circuit diagram

Description

This circuit uses a CA3420 BiMOS op amp to form a picoammeter with 4 ranges. The exceptionally low input current (typically 0.2pA) makes the CA3420 highly suited for use in a picoammeter circuit. Input transient protection is provided by the 1 megohm resistor in series with the input. The 10 megohm resistor connected to pin 2 decouples the potentially high input capacitance often associated with lower current circuits and reduces the tendency for the circuit to oscillate under these conditions. The 10k potentiometer is used for null offset.

Author: Harris Semiconductor
Source http://www.electronics-lab.com/

10:12 0 comments

Small Radio Transmitter Circuit

Circuit diagram 

DESCRIPTION 

 Contains information about building a small radio transmitter, which has a PCB 1.75" x 2.5" (45mm x 68 mm) and has a range of about 30 yards or so. The documentation with the circuit says the freq range is 100-108 MHz, but I have found it to be more like 85-100 MHz. The circuit is (of course) only mono, and accepts an audio input from either a microphone or other source. The input impedance is 1Mohm. The input sensitivity is 5mV and the max input signal is 10mV. The transmitted signal can be picked up on a FM radio. The circuit can be used for short-range transmission, eg. for wireless microphones. The actual circuit comes from a 'Kit', available from Veleman electronics (USA distributor is Tapto Corp., PO Box 1339, CLAREMONT NH-03743-US. UK distributor is High-Q Electronics, 382 Edgware Road, London, W2 1EB). The kit number is K1771. It is a very good transmitter. I bought the kit, and made the circuit, which worked very well. I wanted two transmitters, so I made my own 'copy' PCB and built the circuit, and in fact my home-made version seems to work better than the original!! So there is no need to buy the kit really, as it is quite a simple circuit, and is the best 'home-made' transmitter I have seen. CIRCUIT.GIF is the circuit diagram. PCBPLAN.GIF shows the PCB layout from above (components shown). PCBPLAN.GIF is an accurate layout, scanned from the instruction sheet. I have used * to mark one corner for reference. TRACKS.GIF shows the track layout on the soldering side of the board. This is NOT a very accurate layout. This is because I didn't actually have a plan of the track layout. To get TRACKS.GIF, I put a bit of OHP film onto the bottom of the PCB, and traced the tracks with an OHP pen. I then scanned this in. I have marked the component leg holes (approximately) with white blobs.

CONSTRUCTION

 Start off by scaling PCBPLAN.GIF and TRACKS.GIF by the same amount so that they measure approximately the correct size (1.75" x 2.5") when printed out. Then make your PCB. As mentioned earlier, PCBPLAN.GIF gives the accurate positioning of the holes, whereas TRACKS.GIF gives the positions only approximately. So use PCBPLAN when drilling the holes in your PCB board. Then draw on the tracks, using TRACKS.GIF as a guide. The important thing is to make sure you draw the 'printed coil' correctly on the PCB - those lines are there for a reason!

Parts

• D1 Varicap diode (eg. BB119)
• D2 1N4148
• R1 100K
• R2 220K
• R3 22R
• R4 1K trimmer
• R5 1K
• R6 56K
• R7 1M
• R8 1K2
• C1 5pF ceramic
• C2 6pF ceramic
• C3 15pF ceramic
• C4 trimmer cap
• C5 15pF ceramic
• C6 1nF ceramic
• C7 100uF electrolytic
• C8 4.7uF electrolytic
• C9 100pF ceramic
• T1 BF244A or BF245A FET
• T2 2N3819 FET
• T3 BC307/8/9 or BC557/8/9 PNP

Bear in mind that in addition to the components, there is a jumper wire which needs to be fitted (marked with a dashed line in PCBPLAN.GIF). The power supply to use is 9-14 V DC, one of the little rectangular 9V batteries is fine. Connect this to the + and - points on the PCB. The sound input goes to the points marked "MIKE". The antenna should be connected to the point marked "ANT". The emitter's output impedance is 50 ohms. You can make your own fancy antenna if you like, but I have found that a foot or so of wire is fine.

Good luck with the transmitter. If you have any improvements to the circuit, I would be glad to hear from you. --Dan Evans.

 Author: Dan Evans, dan.evans@sjc.ox.ac.uk
Source http://sable.ox.ac.uk/~sjoh0014/web/dan.html

10:24 0 comments

5V 10A Switching Regulator by L4970A Circuit Diagram

Circuit Diagram

Description
Friends that seek 5V 10A power supply circuit small-sized and build easy. I begs for to advise this circuit. It is 10A switching regulator by use IC L4970A. Then build easy as an example integrated readymade circuit. Important point be power supply input must have 10A current sizes then can give power get enough. The detail is other of the circuit almost must not fine to decorate anything. If friends take an interest try seek buy the integrated circuit and other equipment. come to try build immediately yes.
Image Source www.st.com 

09:33 0 comments

9 Second LED Timer and Relay Circuit

Circuit Diagram

Description

This circuit provides a visual 9 second delay using 10 LEDs before closing a 12 volt relay. When the reset switch is closed, the 4017 decade counter will be reset to the 0 count which illuminates the LED driven from pin 3. The 555 timer output at pin 3 will be high and the voltage at pins 6 and 2 of the timer will be a little less than the lower trigger point, or about 3 volts. When the switch is opened, the transistor in parallel with the timing capacitor (22uF) is shut off allowing the capacitor to begin charging and the 555 timer circuit to produce an approximate 1 second clock signal to the decade counter. The counter advances on each positive going change at pin 14 and is enabled with pin 13 terminated low. When the 9th count is reached, pin 11 and 13 will be high, stopping the counter and energizing the relay. Longer delay times can be obtained with a larger capacitor or larger resistor at pins 2 and 6 of the 555 timer. 

Source

http://www.seekic.com/circuit_diagram/Control_Circuit/9_Second_LED_Timer_and_Relay_Circuit.html

10:09 0 comments

Digital LED Voltmeter Using ICL7107

Description

This circuit is a circuit diagram? digital voltmeterwith LED display. It’s ideal to use for measuring the output voltage of your DC power supply. It includes a 3.5-digit LED display with a negative voltage indicator. It measures DC voltages from 0 to 199.9V with a resolution of 0.1V. The voltmeter is based on single ICL7107  chip and may be fitted on a small 3cm x 7cm printed circuit board. The circuit should be supplied with a 5V voltage supply and consumes only around 25mA. The use of 7805 5V voltage regulator is highly recommended to prevent the damage of ICL7107, 555 ICs and to extend the operating voltages. The following is a schematic drawing:

Parts list of The Digital LED Voltmeter:
R1 = 8K2 R1 = 8K2
R2 = 47K / 470K R2 = 47k / 470K
R3 = 100K R3 = 100K
R4 = 2K R4 = 2K
R5, R6 = 47K R5, R6 = 47k
R7 = 0R / 4K7 R7 = 0R / 4K7
R8 = 560R R8 = 560R
C1,C5, C6, C8, C9 = 100n C1, C5, C6, C8, C9 = 100n
C2 = 470n / 47n C2 = 470n / 47n
C3 = 220n C3 = 220n
C4 = 100p C4 = 100p
C7 = 10-22u C7 = 10-22U
D1, D2 = 1N4148 D1, D2 = 1N4148
IC1 = ICL7107 IC1 = ICL7107
IC2 = NE555 IC2 = NE555
OPTO = CA 10 pin FTA = CA 10 pin

 Author: anonymous
Source  -http://www.hqew.net/circuit-diagram/Digital-LED-Voltmeter-Using-ICL7107_2848.html

09:57 3 comments

60Hz Noise Fillers Adjustable Circuit And PCB Parts Assembly

Description

Regarding this circuit has three change-able notch filters configurations are display .
You can take to used in your small pre-amp or amplifier circuit to filter out any HUM for 50 Hz ( European ) or 60Hz .
With sustituting the capacitors values in the bridge other frequencies can be apply.
About all IC op-amps configuration requires a +/- voltage supply which can easily provided with a voltage divider made of 2 each 100K resistors and a 10 uF filtering capacitor connected from ground to the negative rail . Any op-amps such as the LF353 , TL071, LM308 ,
They can be used and supply from 9 volt battery or other voltage up to 30 volts can be used 

Source-http://www.free-circuit.com/2011/02/11/60hz-noise-fillers-adjustable-circuit-and-pcb-parts-assembly/

09:39 0 comments

Simple LM386 Audio Amplifier Circuit Diagram

Description

This simple amplifier shows the LM386 in a high-gain configuration (A = 200). For a maximum gain of only 20, leave out the 10 uF connected from pin 1 to pin 8. Maximum gains between 20 and 200 may be realized by adding a selected resistor in series with the same 10 uF capacitor. The 10k potentiometer will give the amplifier a variable gain from zero up to the maximum.

Circuit Diagram

Source- http://www.techlib.com/electronics/audioamps.html

09:32 0 comments

Video Signal Emphasis Circut

Description 

With this circuit we can amplification selectively the high signal of picture frequencies [Video] with result bigger clarity than this. The circuit should be placed between a Video unit and the reception Scart or the plug Video input of television receiver. The designing is simple, it’s based in three only transistor. The first stage of Q1 function as isolator - adapter of input impedance. The second stage round the Q2 in common base connection which the gain is determined by the TR2. The TR1, R6 and C3 determine the frequency response. The third stage round the Q3 works as output buffer and 75-ohm line driver. The TR2 should be regulated in a place where the circuit output voltage, to be 1Vp-p, in 75 ohm load. The circuit functions with 12Volts - 50mA well stabilized. 

Circuit diagram 

Part List

• R1=82ohm
• R2=5.6Kohm
• R3-9-11=2.7Kohm
• R4=330ohm
• R5=220ohm
• R6=470ohm
• R7=270ohm
• R8=12Kohm
• R10=2.2Kohm
• R12=180ohm
• R13=68ohm
• C1-4-5=100uF 16V
• C2=2200uF 16V
• C3=470pF ceramic
• C6=470uF 16V
• C7=220uF 16V
• C8=100nF 100V MKT
• TR1=250ohm trimmer
• TR2=500ohm trimmer
• D1=1N4148
• Q1-2-3=BC547
• J1-2=Female RCA jack
• J3=2pin connector 2.54mm step

Video signal emphasis PCB 

Source http://users.otenet.gr/~athsam/video_signal_emphasis.htm

09:45 0 comments