This circuit is one of many that the reader can find in this section for testing crystals. The circuit uses an indicator LED. Transistor Q1 determines the maximum crystal frequency that can be tested.
Lamp Control (CB25902E) This low-current control circuit has a lamp as a load, but can have other...
Suggested by a 90’s Radio Electronics, this circuit automatically activates the recording switch of an...
This voice scrambler is used to obtain effects in the 2.5 to 5 kHz range. The circuit is from...