We found this circuit in a 1980s American documentation. The operational amplifiers of the integrated circuit used can be common types in an experimental setup.
This basic configuration can be found in a lot of articles on this site. In this case, the relay...
This circuit is from American documentation from the 1980s. The transistors are general purpose...
The circuit is simple, as it uses only one transistor and a relay that can be MC2RC1 or MC2RC2,...