This circuit can activate a powerful lamp or call system when a telephone call occurs. Suitable for hearing impaired or noisy places it was found in American documentation in the 90s.
This circuit activates a relay when the conducting bars (probes) are held by a person. The circuit is...
This circuit in the National Semiconductor Fast IC Power Transistor manual uses a special power...
This wireless intercom has a range of about 300 meters using an integrated circuit that is not...