Mini Megaphone (CB8952E)

Found in Popular Electronics' 90s, this small megaphone is based on LM386. The circuit uses a high impedance microphone.

Electroscope (CB497)
Static charges in objects Dan be detected by this sensitive electroscope. The meter indicates when the...
Field Strength Meter (CB22329E)
This simple field strength meter is from a transistor book from the 60's. The transistor is made...
Active Low Pass Filter 741 (CB13322E)
The current drained by this circuit, from a 1976 documentation, is 3 mA and the cut-off frequency is...