This circuit was found in a 90s Wels' Think Tank. The frequency depends on C2 and R3. The handset or speaker must be at least 80-ohm. Observe the low supply voltage.
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....