This circuit is very basic to build. To open a lock which is connected to the K1 Load, you must press each momentary switch in the correct sequence. The sequence used in this circuit is S1, S2, S3 and finally S4. If any of the other switches are pressed the circuit will be reset and [...]

The circuit presented here is a simple audio/video transmitter with a range of 3 to 5 metres. The A/V signal source for the circuit may be a VCR, a satellite receiver or a video game etc. A mixer which also operates as an oscillator at VHF (H) channel 5 TV frequency is amplitude modulated by [...]

C1, C2, C3, C4 = 10 – 80pF C 5 = 10nF C6 = 1000pF C7 = 100nF C8 = 2200mF/35V L1 = 1 coil with diameter of 10 mms, 1 mm L2 = 7 coils with diameter of 10 mms, 0,8 mm L3 = 3 coils with diameter of 10 mms, 1 mm TR1 [...]

This digital thermometer use DS1820 measurement temperature from 0-99 ‘C then the temperature will display on LCD 1X16 .The CPU used in this project is PIC16F84A. Software programming with CCS C Compiler. Download CCS Source code

This circuit uses an MC2830 to form a voice activated switch ( VOX ). A traditional VOX circuit is unable to distinguish between voice and noise in the incoming signal. In a noisy environment, the switch is often triggered by noise, or the activation sensitivity must be turned down. This circuit overcomes this weakness. The [...]

From http://www.elecfree.com/circuit/electronic-control/sound-scr-swith-by-ic-1458-scr-c106d/

We have all seen the commercial on TV ………. CLAP – ON – CLAP – OFF – THE – CLAPPER ………… well here is a circuit that will perform that same function. Circuit operation is as follows. A single hand clap will be picked up by the electric mic which is coupled through C1 into [...]

There is a lot more to designing an FM transmitter, than meets the eye. Here is a typical FM transmitter circuit. It consists of 3 stages. An audio amplifier, RF Oscillator and RF output. Read More Source : http://www.talkingelectronics.com/te_interactive_index.html