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.

LM158 Function Generator (CB4481E)
Two operational are used on this triangular-rectangular oscillator suggested by Motorola in its...
Astable 4093 (CB21125E)
This circuit from a Popular Electronics from the 90's can generate signals from 0.03 Hz to 3 kHz...
10 W Amplifier TDA1910 (CB15228E)
With 8 to 30 V power supply, the output power depends on both the voltage and the load. The...