Digital Circuits


IR–S/PDIF Transmitter

The best-known ways to transmit a digital audio signal (S/PDIF) are to use a standard 75Ω coaxial cable or Toslink optical modules with matching optical cable. Naturally, it can happen that for whatever reason, you cannot (or don’t wish to) run a cable between the equipment items in question. With a wireless solution, you have […]


Toy Organ

This circuit produces a tone according to the button being pressed. Only 1 button can be pressed at a time, that’s why it is called a monophonic organ. You can change the 1k resistors to produce a more-accurate scale. Circuit diagram Parts: R1-4 1k Resistor R5 4.7k Resistor P1 10k Trimpot (Potentiometer) S1-5 Switch C1 […]


Ultra Low Power LCD

This circuit serves as an ultra-low power replacement for multiple LED on-off indicators. It also has the advantage of being easy to read in full daylight. With the parts shown, it is possible to display four bits of information.The display that I used has three digits and 2 decimal points for a total of 23 […]


Build The Decision Maker

Can’t make a decision? Worried that if you make the wrong choice you’ll get the blame? Well, here’s your saviour: press the button and the decision is made for you. Instantly. And if that decision turns out to be the wrong one, you can always say to your mum / dad / teacher / partner […]


Circuit Project:Tiny Door Guard

This simple Door Chime protects the door and gives a loud Alarm tone when there is an attempt of theft. The circuit is too simple and battery operated. A Normally Closed (NC) reed switch and magnet is used to trigger the circuit. Alarm generator is the popular ROM IC UM 3561. This 8 pin IC […]


Hacks and Mods: No Fly Zone

Remote controlled scale helicopters can be really amazing toys. But such toys can be quite a nuisance in some areas or workplaces. Some places and situations require full focus and concentration. It is in these places where such a toy can become as annoying as a fly circling around the head. That is the reason […]


Electronic Cricket Match Game

This electronic cricket is a present for Kids. This simple battery powered circuit can be used to play Cricket Match with your friends. Each LED in the circuit indicates various status of the cricket match like Sixer, Run out, Catch etc. The Circuit uses two ICs ,one in the Astable mode and the second in […]


DIY Tremolo Effect

This tremolo effect circuit uses the XR2206 and the TCA730 IC which is designed as an electronic balance and volume regulator with frequency correction. The circuit is use full for stereo channels and it also has the ability to simulate the Lesley effect aka rotating loudspeaker effect. How does the tremolo effect circuit works Balance […]


Polyphonic DoorBell

Here is an AC triggered Multitone, polyphonic doorbell. It gives eight melodious tunes for 2 minutes. On each press it will give a new tone which will continue till the melody is over. The circuit is too simple and battery operated It uses the popular melody generator IC UM3481. The circuit uses the popular melody […]


Model Railway Time

Here is a circuit that will convert any clock mechanism into Model Railway Time. For those who enjoy model railways, the ultimate is to have a fast clock to match the scale of the layout. This circuit will appear to “make time fly” by turning the seconds hand once every 6 seconds. The timing can […]