Suggested by a 90’s Radio Electronics, this circuit automatically activates the recording switch of an old tape recorder. It can be adapted for other purposes.
This small source is suitable for low consumption equipment that uses batteries. The circuit is...
This circuit was found in a 1980s US publication. There may be some difficulty in obtaining the...
The bipolar transistors can be the BC548 and the FET a BF245. This configuration has a time...