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A very high quality intercom, which may also be used for room monitoring.... [read more]

The bi-directional sequencer uses a 4 bit binary up/down counter (CD4516) and two "1 of 8 line decoders" (74HC138 or 74HCT138) to generate the popular "Night Rider" display. A Schmitt Trigger oscillator provides the clock signal for the counter and the rate can be adjusted with the 500K pot.... [read more]

The sunset lamp comes on at full brightness and then slowly fades out over 1.5 hours time and stays off until power is recycled.... [read more]

Here is a simple thermostat circuit that can be used to control a relay and supply power to a small space heater through the relay contacts. The relay contacts should be rated above the current requirements for the heater.... [read more]

A simple STEREO amplifier, with minimal external components. It use one only opamp., that is capable to give output power 2X5W in the 4 ohms, with distortion 0.5%.... [read more]

This is a circuit for alternative sources selection. It combines mechanical selection using a rotating switch S1, the electronic drive of the relays RL 1-10 and also the optical indication of the selection by the Display DSP1.... [read more]