Dingdong Sound Generator
This is the circuit diagram of a ding dong sound generator based on two NE555 timer ICs.The circuit is designed to toggle between two adjustable frequencies to produce the ding dong sound. The first NE555 (IC1) is wires as an astable multivibrator operating at 1Hz. The frequency of the second NE555 (IC2) is modulated by the output from the first IC. MORE...>
Power Supply 120 MA
12V/120mA switch mode power supply circuit.Transformer less switch mode power supplies have become very popular these days. The circuit shown below is of a 12V/120mA output, 85 to 230V AC input transformerless switch mode power supply using LNK304 IC. Applications of a power supply based on this IC includes hand held devices, timers, small appliances, LED drivers, industrial gadgets etc.LNK304 is a low component count, efficient off-line switcher IC that can support buck, buck-boost and flyback topologies. MORE...>
Stereo Decoder Circuit
In FM stereo transmission left and right channels are algebraically encoded into sum (left + right) and difference (left-right) signals. This is done in order to make the mono FM receivers compatible with the stereo transmission. The mono receiver will reproduce the summed left and right channel and the listener will hear both these channels through a single loud speaker. Stereo decoder is a circuit which is used in stereo FM receivers in order to recover the left and right channel information from the composite transmission signal. This task is achieved by adding the difference signal to the summed signal to recover left channel and subtracting the difference signal from the summed signal to recover the right channel. MORE...>
