Cool Antique Stuff
In this area I write about things I probably scavenged off facebook or on the street. Hopefully it makes sense?
Knight R/C Tester
I've been searching for an old condenser tester for years now and finally came upon this one at an estate sale. It appears similar in construction to the Heathkit C-3 Condenser Tester.
It was made from a kit of parts. I found the manual online and it provides highly detailed assembly instructions.
There is a 6X4 tube inside to rectify AC mains, as well as a 'magic eye' tube to indicate capacitance and leakage. It can also measure resistance, but I am planning on using it mostly for its leakage test.
The set is actually pretty clever. It uses a Wien bridge with four resistors and some capacitors (one of which is the unknown resistor/capacitor). The balance control adjusts a resistor on the bridge until the potential at both middle nodes is equal. This balances the bridge, so no current flows through the indicator tube. The correct R/C value is indicated when the magic eye is open widest.
I am planning on using it primarily for leakage testing. This set tests current leakage at actual working DC voltages at 50V, 150V, 250V, 350V, and 450V. I'm hoping this will provide better readings than modern meters, which apply lower test voltages.