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In a lot of cases we needed a 220VAC voltage, in spaces where it does not exist, in order to we supply with power, various small appliances. In the Fig.1, exist a voltage converter circuit from 12VDC in 220VAC, with output power roughly 50W.... [read more]

This circuit operates a LED in pulsing mode, i.e. the LED goes from off state, lights up gradually, then dims gradually, etc. This operation mode is obtained by a triangular wave generator formed by two op-amps contained in a very cheap 8 pin DIL case IC. Q1 ensures current buffering, in order to obtain a better load drive. R4 & C1 are the timing components: using the values shown in the parts list, the total period is about 4 seconds.... [read more]

his remote transmits a tone using an infa-red LED. This tone is decoded by the receiver. Since the receiver only switches when it "hears" the tone, there are no accidental activations.... [read more]

This is a great intercom circuit that can be used in many ways. It uses 22V to operate and maybe it will work at a lower voltage (you can try it). For input/output it uses a loundspeaker (20-45 Ohm) on each side.... [read more]

This circuit was purposely designed as a funny Halloween gadget. It should be placed to the rear of a badge or pin bearing a typical Halloween character image, e.g. a pumpkin, skull, black cat, witch, ghost etc. Two LEDs are fixed in place of the eyes of the character and will shine more or less brightly following the rhythm of the music or speech picked-up from surroundings by a small microphone. Two transistors provide the necessary amplification and drive the LEDs.... [read more]

Oscilloscope testing module (huntron circuit)... [read more]