This circuit has an automatic dynamic gain control in a range of 6 dB to 40 dB. We found it in documentation from the 90s. The bipolar transistor is a general purpose type.
This circuit was found in a Philips documentation from 1966. The circuit provides 1 mW with a...
This simple timer or timer activates a low current bell or a buzzer according to the supply...
Found in old American documentation, this receiver receives modulated infrared signals and...