Plant soil heater (CB7964E)

This circuit was found in a 90’s 303 Circuits. The components are from the period and the heating system depends on the resistive element.

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SCR Switch II (CB19272E)
This circuit shows how to trigger and shut down an SCR using common pressure switches. The circuit...
Operational with Hysteresis LM309 (CB15103E)
In the figure we have the way to add hysteresis to an operational amplifier. The relationship...
50 MHz transceiver (CB18653E)
The range of this transceiver found in an old national publication is of the order of 1 km. The...