Moog Transistor Matcher Questions

[Grant Richter]

It's also difficult during winter because the furnace is cycling around a 5
degree deadband. If you turn the furnace off, then you have (hopefully) a
long temperature droop. At 2.2mv per degree C (or about 1mv per degree F)
the room temperature needs to be stable for about 10 minutes to get a group
of transistors at the same temperature.

So set your thermostat down before you start so the furnace doesn't kick in
while matching.

> From: jhaible at t-online.de (jh.)
> Reply-To: owner-synth-diy at node12b53.a2000.nl
> Date: Sat, 30 Dec 2000 14:17:06 +0100
> To: ">>>marjan<<<" <urekar.m at EUnet.yu>
> Cc: "diy" <synth-diy at node12b53.a2000.nl>
> Subject: Re: Moog Transistor Matcher Questions
> 
>>> I've noticed that the measurements aren't steady at all. Once I turn
> the
>>> power on, the voltage reading on the voltmeter seems to drop as I watch.
>> 
>> :) This is very obvious illustration of all the talk about the need for
>> temp compensation of expo pair. You see how it changes with temperature.
>> Try to do it in constant temp room, away from open air flow (window,
>> doors).
>> Also be sure to use tweezers to pick and install transistors you test as
>> heat from your fingers heats transistor a bit and you get some reading
>> that
>> quickly changes as heat is dropped. That's how sensitive it is...
> 
> Very true. It's a pain.
> Last time I matched transistors, I arranged them so that I only had to touch
> them with my fingers for a second or less, but I still had to wait more
> than a minute or two for each transistor's measurement.
> 
> I have an idea how I will do it next time, but I have not tried it yet:
> 
> I'll stick a whole batch of transistors side by side into one of these
> white, solderless prototype boards, and I'll make a cable with 3-pole
> plug to contact the protoboard from the Vbe test circuit. Then the
> procedure would be:
> 
> Stick in 20 transitors at once, wait 2 minutes (or even 5) until they
> are all settled, and then probe them with that special plug one by one,
> (hopefully) without stirring their temperature.
> 
> Anybody tried this ?
> 
> JH.
> 
>