Found in a 1990s American technical brochure, this circuit is intended for alarms that use as photodiode sensors. The circuit has a frequency response of up to 20 kHz. The gain is 40 dB.
This circuit sensor is an NTC with a resistance of the order of 2k. The SCR can be from the TIC...
The load current can be adjusted up to about 1 A. The transistor can be TIP32 or TIP42. The...
This oscillator with common general-purpose transistors appeared in Radio Electronics magazine in...