Astable 555 (CB21101E)

This 50% duty cycle configuration was found in a Popular Electronics from the 1990s. The operating frequency is given by C1.

Low Consumption Pulsator (CB20346E)
This circuit produces the ticking of a clock on a common piezoelectric transducer. The circuit has an...
Band Pass Filter 741 (CB16220E)
The basis of this circuit is a double T in the feedback, which has the components calculated to...
Phototransistor Optical Ttrigger (CB14648E)
This configuration was found in the Texas Instruments optoelectronics manual. PNP transistors...