JFETS, matching etc.

temol said:
Ok.. Tayda jfets are jfets.. thats' t the meter probably.
Those cheap LCR meters are not the best choice for JFET measuring. I have one and do not use it for jfets because readings are off.

Mourguitars - can you measure the same transistors with this simple setup?
View attachment 1344

T.
Click to expand...
Be damned sure you have a FET and it's hooked up the right way. Hook it up wrong or try that with a BJT and you could burn it up. If you want to do this safely, put a 10K resistor between the battery + terminal and the JFET drain.

Respect to the guys at Runoffgroove!
 
Last edited:
I sent Mr Pedalpcb a pic that I can’t upload , but I wrote down all the readings..I got readings all over the place like CDB said above I had FETs and BJTs so I didn’t want to do that test other than the meter

Mike
 
Last edited:
I've never worried about any protection because I have dedicated adapter for smd, socket for through hole and I do not mix bjt and fet stuff ;)
But of course it's a good advice.

T.
 
page-12

Heres my readings i took with a tester, all over the map and 2 different types..file is to big to post here so i uploaded it over there

Mike
 
Can you take one of the J201 transistors and make comparison of Vgs readigns from DMM method and transistor tester?

T.
 
My transistor tester arrived yesterday.
transistor tester.jpg
What a cool device! Measures wah inductors no problem. I tried measuring a guitar pickup, but the winding resistance is so high that the tester thinks it's a resistor and can't measure the inductance. Try testing 2-color LEDs in a darkened room... it's a mini light show!
Only complaint is that it doesn't measure Idss & Vp on JFETs. I still have to do that manually until I can find my Heathkit curve tracer. Assembling the case is tricky, it's like building a house of cards. I wasn't going to cheat & use tape.
Warning: don't try to use a guitar pedal power supply to power this up because this thing is wired for a positive center pin. When I'm not using a 9V battery, I'm powering it with a 12VDC power supply left over from an old router.
 
https://www.ebay.com/itm/2019-Versi...ance-ESR-meter-Signal-Generator/182678167951?

I bought the assembled board with the clear case. The case has two tops, one that covers everything except the dial & ZIF socket, one that covers the top half of the board only. Mine is assembled with the top half cover. I tried the full cover, but the ZIF lever is too hard to get at and the knob wasn't pefectly centered and dragged on the cover. You can buy the board fully assembled, or a kit of parts with instructions. There is a ton of info here.
 
Thanks. Will check that out. Hard to argue with paying less than $4 more to get the assembled board instead of the DIY kit.
 
These were not to bad to do once i got a system that worked for me they all tested in the same ball park vs the other pic i posted of the Ebay J201's...those might be good but my first two builds used them and didn't turn out so well..im pretty gun shy on using them.

Mike

https://imgur.com/3EQgA3Y
 
You must log in or register to reply here.

Similar threads

MichaelW
DEMO Circulator (EQD Grand Orbiter)
Replies
18
Views
2K
gri
G
Back
Top