Low Voltage Test (CB22158E)

This is a simple voltage tester for voltages from about 2V to about 15V with the indicated resistor and red LEDs.

XTAL Astable Multivibrator (CB12000E)
This multivibrator has its frequency controlled by a crystal. Other frequencies can be generated by...
Triac Power Control (CB6551E)
We found this circuit in a 1964 Electronic Design. The triac and SCR can be replaced with modern...
Low Pass Second Order Filter 741 (CB25818E)
This unity gain circuit was found in the February 1995 Electronics Now magazine. The frequency is 10 kHz,...