Author Topic: U426 dual jfet transistor  (Read 1720 times)

Jussi

U426 dual jfet transistor
« on: March 08, 2013, 10:07:05 AM »
I got four of these transistors. I'd really like to hear these things but I don't know how to set them up. Some of the specs looked a little same than with J201. Is it possible to make a booster or two stage distortion pedal with one of these if using only 9 volts from a battery?

Datasheet: http://www.datasheetarchive.com/dataframe.php?file=Book-42094.pdf&dir=Databooks-4&part=U426#

If I'm using 9 volts, how big resistors or trimpots I should put for drain and source pins to even get some sound? What should be the voltage at the pins? And do I need big capacitors (like 50 F) from source pins to ground?


EDIT: not sure if these are germanium but when i googled these i found somebody selling them as germanium transistors at ebay
« Last Edit: March 08, 2013, 03:03:06 PM by Jussi »

kingswayguitar

Re: U426 germanium dual jfet transistor
« Reply #1 on: March 08, 2013, 02:44:55 PM »
can i ask where you bought them? i wouldn't mind trying a few. the datasheet doesn't indicate, but i wonder how closely they're matched. the datasheet also doesn't say they're germanium??

to answer your question....i'd just look up jfet boost or common source amplifier. lots of discussion at this forum about the subject. not too tough. your battery is drawn backwards by the way. and you don't need such a big capacitor, anything over about 0.1 uF starts to help. 50 is fine though.

oh yeah, and notice your jfets are directly (dc) coupled because there's no capacitor between them. this is possible but involves differences from transistors that are decoupled with a capacitor.

darron

Re: U426 germanium dual jfet transistor
« Reply #2 on: March 08, 2013, 02:46:03 PM »
Huh? A dual germanium jfet? Really? :D

You could make a mu-amp stage...

Schematic at the bottom:

http://www.geofex.com/Article_Folders/modmuamp/modmuamp.htm
Blood, Sweat & Flux. Pedals made with lasers and real wires!

PRR

Re: U426 dual jfet transistor
« Reply #3 on: March 08, 2013, 06:39:26 PM »
They were made by Siliconix.

Jussi never said "germanium".

> i wonder how closely they're matched. the datasheet

Bottom of first page, "MATCH".
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darron

Re: U426 dual jfet transistor
« Reply #4 on: March 08, 2013, 07:16:00 PM »
What the heck. Thought I saw it in the topic title when it was posted.  Then again was 6:30 am or something. Thays ehy it dodnt make sense to me. Dual matched jfet a in a package would be so useful

It's "Kurns"

No it's not.

Disregard.
Blood, Sweat & Flux. Pedals made with lasers and real wires!

kingswayguitar

Re: U426 dual jfet transistor
« Reply #5 on: March 08, 2013, 07:58:18 PM »
They were made by Siliconix.

Jussi never said "germanium".

> i wonder how closely they're matched. the datasheet

Bottom of first page, "MATCH".

thanks
MATCH is written vertically so I missed it  :icon_redface:
and i see one listing on all of ebay C $9.22 for 2
that seller does claim they're germanium
hmmmmm

J0K3RX

Re: U426 dual jfet transistor
« Reply #6 on: March 08, 2013, 09:15:52 PM »
From FET Design Catalogue 1979... Bet you won't find many of these too often!
Doesn't matter what you did to get it... If it sounds good, then it is good!