madbeanpedals::forum

General => Open Discussion => Topic started by: lego4040 on March 10, 2017, 06:23:24 PM

Title: TagBoard Jfet Tester
Post by: lego4040 on March 10, 2017, 06:23:24 PM
Help, I'm about to test my j201's and I need a TL071 or Similar. I can't find those in my stash of coarse but I do have a TL082,JRC4558D and NEC5532. A quick internet check says those are good audio subs but I'd like to get a Amen from guys I trust over here. I'll try and do a short video and post today or tomorrow
Title: Re: TagBoard Jfet Tester
Post by: Haberdasher on March 10, 2017, 06:51:35 PM
the rest of those you listed are dual opamps, and those would be okay subs for a tl072.  but a tl071 is a single opamp with a different pin arrangement.  therefore none of them will work as a plug-in sub for your tester.

ne5534, tl071, lf351 are subs but it doesn't sound like you have any of those so you might as well hit tayda up for a 071.  or try the parts jar area in the b/s/t.
Title: Re: TagBoard Jfet Tester
Post by: lego4040 on March 10, 2017, 07:52:13 PM
Banging head against wall, I know I have some but that will be ordered on next parts list order. I got the Boneyard PCB in  ;D looks awesome Haberdasher
Title: Re: TagBoard Jfet Tester
Post by: shedland on March 10, 2017, 09:15:32 PM
Hi

Not sure what testing you were planning on doing, but if it were FET matching, this uses a TL072.
Title: Re: TagBoard Jfet Tester
Post by: shedland on March 10, 2017, 09:16:21 PM
It puts the URL in the reply!


http://tagboardeffects.blogspot.co.nz/2012/07/greatly-improved-jfet-matcher.html
Title: Re: TagBoard Jfet Tester
Post by: Haberdasher on March 10, 2017, 09:47:06 PM
huh, yeah that linked one says you can use 072.  the one i etched a long time ago used tl071 so I ass-umed it was the same design, doh!.

Quote from: lego4040 on March 10, 2017, 07:52:13 PM
Banging head against wall, I know I have some but that will be ordered on next parts list order. I got the Boneyard PCB in  ;D looks awesome Haberdasher
thanks dude
Title: Re: TagBoard Jfet Tester
Post by: lego4040 on March 10, 2017, 09:47:31 PM
Hmm, on the tag board site the one I'm looking at and built uses the tl071. I will look at this page again and see if it's a typo. This is for Jfet matching
Title: Re: TagBoard Jfet Tester
Post by: lego4040 on March 10, 2017, 09:54:21 PM
My version of build http://tagboardeffects.blogspot.co.nz/2012/07/jfet-matcher.html?m=1
Title: Re: TagBoard Jfet Tester
Post by: lego4040 on March 10, 2017, 11:02:39 PM
Ok so I have a TL082 which I'll use for the T072 version. I have another perfect I can use but apparently theirs is this version that uses no Op Amp and is just as good
Title: Re: TagBoard Jfet Tester
Post by: lego4040 on March 11, 2017, 05:24:04 AM
So I built the one shedland postedhttp://tagboardeffects.blogspot.co.nz/2012/07/greatly-improved-jfet-matcher.html (http://tagboardeffects.blogspot.co.nz/2012/07/greatly-improved-jfet-matcher.html)and it works  :) Tim for bed, will post readings tomorrow night after a day of running around. Oh I I built it in a kitty cat can
Title: Re: TagBoard Jfet Tester
Post by: EBRAddict on March 11, 2017, 01:16:54 PM
If you have the pinouts right, I doubt anyone could notice a difference in the TL072, 4558 or TL082 used for JFET matching.
Title: Re: TagBoard Jfet Tester
Post by: lego4040 on March 11, 2017, 04:09:13 PM
These are my numbers using the TL802. Switch up for idss and switch down for vps
I'm no guru but I'll use the closest 6 and continue building from there. I've had nothing but setbacks all week. I blew out my ankle and spent evening I ER last week and found out my car was towed this morning  >:( so no we got to get car before we go go to confirmation
Title: Re: TagBoard Jfet Tester
Post by: Muadzin on March 20, 2017, 10:40:05 AM
Maybe the universe is trying to tell you something in regards to the use of JFET's?  ;)


Seriously, that's tough luck. Here's to hoping your luck will improve. Best wishes!
Title: Re: TagBoard Jfet Tester
Post by: lego4040 on March 20, 2017, 02:54:28 PM
Well the good thing is that the pedal works. I'm waiting for enclosures to come in so I can trim everything and box it up. The Wampler Pinnacle sounds great, from clean boost to subtle Gain to over the top crunch. I hear ya on the Jfet's tho, I just bought a matched quad of 5457's Jfet from smallbear for the Nom Nom@10 bucks. Yeah, I'll buy a fistful of smd's and make my from now on.