AC voltage probe (CB8185E)

This circuit for voltages up to about 20 V was found in a 90s Popular Electronics. The LED can be of any type or color.

Mini Animatronic (CB20429E)
This circuit was originally designed to drive an engine with a small flower that dances when the...
Amplifier for tunnel diode (CB23848E)
In the figure we have an RF amplifier for tunnel diode. The frequency range will depend on the...
Middle Control (CB955E)
Using two common operationals, such as 741, this circuit serves as a medium control in an...