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Old 6th Apr 2018, 12:22 am   #23
Argus25
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Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
Posts: 2,679
Default Re: Discussion of subcircuits for homebrew valve testers

Quote:
Originally Posted by Thatvalveguy View Post
Hickock testers[/B]
The hickock units, well their bridge? approach is a nice idea. However it cannot be calibrated by a voltmeter.
Yes it can, except for just one adjustment, the sensitivity of the meter bridge, which is done with their method simply by applying an AC source (which is checked by an AC voltmeter) via a resistor to unbalance the bridge, or with my method using a current sink, which is itself calibrated by a voltmeter, so it could be included inside the unit.

The Hickok TV10 has excellent meter marking in uMhos and scale switching options and is better made than many supposed laboratory grade lab instruments I have seen, so you will be hard pressed to beat it, but it is a good challenge that is for sure.

The TV7 is not quite as good in this respect due to the meter and it was designed more to help technicians in finding serviceable parts. As were some of the domestic style Hickok testers with good/bad pass fail meters which are not laboratory instruments, not to be confused with a TV-10.

The Hickok tester with the additional metering is the TV2.

Last edited by Argus25; 6th Apr 2018 at 12:30 am.
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