We found this circuit in the 1964 RCA transistors manual. The transistors used are uncommon today, but they can be used equivalent. The circuit controls the operation of a heating element.
In the figure we have a simple signal tracer circuit to be coupled to the volume control of an AM...
This circuit was found in documentation from the 90s, using components from that time. The...
This circuit, obtained from old documentation, allows the recovery of sulfated batteries. The...