heath: Notes on the Heathkit C-1 condenser checker

The Heathkit C-1 uses a 12A6 as rectifier and a 1629 eye tube.  Resistance and capacitance are measured in a direct-reading bridge circuit. The eye opens when the correct resistance or capacitance is selected by way of the main dial potentiometer. As with all such bridge devices, accuracy is dependent on the precision of the standard capacitors and resistors in the device.

An electrolytic can be reformed in step-wise fashion. The neon bulb (below the eye tube) lights when the reforming current is about 2 mA or more. The reforming process starts with the voltage step switch set at the lowest voltage at which the neon bulb lights. As reforming progresses, the neon bulb will go out when reforming current drops below 2 mA. At that point the next higher voltage step can be selected until the capacitor shows full proper voltage on an external voltmeter. When the reforming process is complete,  the tester's power is switched off and the step switch moved to the "R" position to quickly bring the voltage across the capacitor back to zero. The "R" setting places a 1000 ohm resistor across the test leads.

 

Model C-1 was replaced by model C-2 in January 1950 according to the notation on the C-2 schematic.