http://aronnelson.com/gallery/album76/JFET_Matcher_LAYOUT (http://aronnelson.com/gallery/album76/JFET_Matcher_LAYOUT)
I decided I would go ahead and build yet another phaser (phase 90) and need to match the fets. I came across this and looks great. But- How does it work? I can see where the transistor would be placed and 2 leads of the dmm, but what about the grounds? Anything connect to that/those? I assume the neg lead of the battery and the posit goes to the +9v. Anything else I need to know to match these damned things? What do you set the dmm to while testing?
Im also looking for a Phase 90. The one at Tonepad doesnt seem to be available :(
Maybe Ill just change my forum name from jimbob to clueless :)
hey jimbob
yeah you only need to connect the ground to the neg lead on your battery
i would not use a battery myself as the voltage will drop as you test your fets and give you slightly differnt results. use a wall wart and dc jack.
if you are testing 500 fets at a time then you may end up with very different results that differ enough to throw them out. then end up having to recheck everything.
http://aronnelson.com/gallery/album75/Fet_Matcher_1 is the one i built and it works very well. its a bit easier as its on vero.
cheers
ulysses
depending on the fets you are matching you will need to set your dmm to the voltage that is the on/off switch voltage of the fets
so for 5458's like i used i set my dmm to under 2000mv and it gave results in the 700-1170mv range.
i found that if they were a couple of mv out then they would still phase ie, 832mv and 834mv would work.
cheers
ulysses
Quote from: ulysses on December 19, 2006, 05:35:09 PM
i would not use a battery myself as the voltage will drop as you test your fets and give you slightly differnt results. use a wall wart and dc jack.
cheers
ulysses
Nahhh! :)
I use a battery and the difference is minimal at the most.
It's not an exact science, it's gets you close enough that whatever you need matched JFETs for, it should work fine.
depends how many you are matching
i was matching 500 and the results did slip by 5-10mv by the end of it.
enough to make me think that there were less matches that there actually were.
cheers
ulysses
Quote from: ulysses on December 19, 2006, 08:58:26 PM
i was matching 500 and the results did slip by 5-10mv by the end of it.
cheers
ulysses
:o
Now
that's a different story!!