View Single Post
Old 17th Feb 2010, 2:57 pm   #169
Rest in Peace
Join Date: Aug 2009
Location: East Preston, Sussex
Posts: 162
Default Re: The "Sussex" Homebrew Valve Tester.

I dont think that much needs to be done to the H/K leakage, AVO only use 50v for insulation testing,very similar to the Sussex. Using the LED, a 47k leakege just illuminates the LED, bearing in mind that in most cases, the cathode resistor is usually a low value, which is by-passed, the impedance at the cathode is low, so 47k leakage would have very little effect on performance, and this can be seen on the LED.
In the case of the main leakage LED, any leakage is amplifed by the transistor and on my tester a 10M resistor just illuminates the LED.
If you want a more sensitive leakage indiactor on the H/K duplicate the main leage circuit. Be warned however, a 1M H/K will light the LED brightly, and you could be discarding valves which are perfectly serviceable.

swordholder is offline   Reply With Quote