This circuit triggers a relay when the set temperature is reached. The circuit is from an old documentation. The relay may be equivalent according to the transformer secondary voltage.
The transistors of this amplifier for 8-200 headphones may be the BC548 or equivalent to replace...
This high gain small signal amplifier circuit was found in an old publication on transistors....
This General Electric circuit was found in a 1964 documentation. The circuit triggers a relay when...