This circuit uses a pickup coil to take the signal from a telephone line without contacts. The circuit is from a 90s Popular Electronics.
This new AMS device consists of a digital color sensor and proximity sensor that also incorporates an infrared...
This amplifier produces a few hundred milliwatts of Input 100 pF audio over a load of 4 or 8 ohms...
This transmitter for modulated infrared remote control was found in documentation from the 90s....