Ultrasonic Remote Control Test (CB21309E)

This circuit was found in a Popular Electronics from the 90s. The circuit uses an ultrasonic microphone. The indicator is dual with LED and Buzzer.

| Clique na imagem para ampliar |

1.78 MHz Telephone Transmitter (CB16689E)
This 1992 circuit operates in the range of cordless phones used at the time. The circuit is based...
Fluorescent Flasher (CB17350E)
This different circuit uses a relay as an oscillator, whose frequency is determined by C1, and to...
Antenna Amplifier (CB3869E)
This antenna or booster amplifier operates with signals from the midband (MW) range up to the VHF...