We found this circuit in the Texas Instruments optoelectronics manual. Field effect transistors can be BF245 and bipolar BC548. The sensor is a photodiode in the photo-generator mode.
The output voltage of this circuit is approximately four times the supply voltage. The circuit is from...
This circuit was obtained in an Electronics World of 1968. The operational amplifiers ones are...
Found in a Hands-On Electronics from the 90s, this circuit produces the dial tones of an old...