This simple logic level tester was found in Radio Electronics from the 90s. The inverters are of the 4009 type and the power comes from the circuit being analyzed.
The use of field effect transistors in this circuit improves its performance. This configuration is from a...
This is a simple source indicated for powering low voltage projects on the bench. The circuit is...
This circuit was found in a 1969s American documentation. With modern components, it can be used...