Thermostatic relay (CB21285E)

We found this circuit in an old QST magazine. The circuit is powered according to the thermostatic relay used.

50 W Amplifier (CB6180E)
Found in a 1967 Delco documentation, this circuit can deliver power from 40 to 50 W at 8-ohm load....
Temperature Controller (CB6017E)
This circuit is from a factory documentation (National Semiconductor) of the 80's. The power...
4.5 W Amplifier (CB6298E)
This 1968 Mallory circuit uses an uncommon integrated circuit today. The circuit has a 30 to...