We found this circuit in an old American documentation. The circuit can be adapted for modern applications, since the integrated circuit used is uncommon nowadays.
This telegraph monitor was found in an American documentation for radio amateurs from the 1970s. The...
We found this circuit in a European publication from the 1970s. The transistor is made of...
This adjustable source from 2 to 15 V uses transistors from the 60's, as indicated in the...