Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

John Curl's Blowtorch preamplifier
John Curl's Blowtorch preamplifier
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Closed Thread
Thread Tools Search this Thread
Old 25th September 2007, 12:05 AM   #2101
apassgear is offline apassgear  Mexico
diyAudio Member
apassgear's Avatar
Join Date: Nov 2002
Location: Viña del Mar, Torreon
Gee Grey... you are getting older than me
Old 25th September 2007, 12:15 AM   #2102
MikeBettinger is online now MikeBettinger  United States
diyAudio Member
Join Date: Jan 2006
Location: New Jersey
Originally posted by GRollins
Good grief, Mike...you forgot the tone controls.
(Next time use a bigger project box. How the dickens do you get your fingers in there?)
I rarely use a pre-chosen current. The current I use is generally dictated by the circuit rather than vice versa. It's easy enough to measure Idss and at least as versatile.
Actually, the tone controls are on the backside... and, if you look closely there are spacers between the top cover and the case because of my optimisum that it would all fit was misguided.

The current I use is based on the application, I dial it in to match.

Unfortunately I just bought a pile of FETs and now I'll need to figure out how it works, again. I know I have a schematic somewhere...

"We are all agreed that your theory is crazy. The question which divides us is whether it is crazy enough to have a chance of being correct. " Niels Bohr
Old 25th September 2007, 12:21 AM   #2103
john curl is offline john curl  United States
diyAudio Member
john curl's Avatar
Join Date: Jul 2003
Location: berkeley ca
How about in a cabinet under the sink?
"Condemnation without Examination is Prejudice"
Old 25th September 2007, 12:51 AM   #2104
john curl is offline john curl  United States
diyAudio Member
john curl's Avatar
Join Date: Jul 2003
Location: berkeley ca
Does anyone know how to purchase very small self sealing bags? My former tech bought the ones that I have here, and I have never sourced them. They ARE perfect for TO-92 devices, and are relatively tough, so they don't puncture too easily. Even if they do puncture, and 1 or 2 devices escape, it is easy to find where they came from, because of the puncture in the bag. One of the advantages of these little bags is that they lay flat against each other, saving space. You could put 1000 devices under your mattress and not be bothered. If you have unmeasured devices, you can put them in a ' ? ' bag that can be sorted later, or used one at a time for a current source (with a series resistor), etc.
"Condemnation without Examination is Prejudice"
Old 25th September 2007, 12:55 AM   #2105
Magura is offline Magura  Denmark
diyAudio Member
Magura's Avatar
Join Date: Oct 2003
Location: Denmark, Viborg
Originally posted by john curl
Does anyone know how to purchase very small self sealing bags?


Everything is possible....to do the impossible just takes a little while longer.
Old 25th September 2007, 01:00 AM   #2106
john curl is offline john curl  United States
diyAudio Member
john curl's Avatar
Join Date: Jul 2003
Location: berkeley ca
"Condemnation without Examination is Prejudice"
Old 25th September 2007, 02:40 AM   #2107
GRollins is offline GRollins  United States
diyAudio Member
Join Date: Feb 2001
Location: Columbia, SC
Your parts have never gotten mixed on the bench while you're building a prototype and trying different Vgs values, etc? You're a lucky fella.
As far as I know, we are all aging at the same rate. If I'm pulling ahead, then perhaps I should see if there have been any modifications to the Lorentz contraction equations that allow time to advance faster here than in other places. I mean, I know that I move slowly, but I didn't realize that the difference was sufficient to be relativistically significant.
And I thought I was the only one who ever had to find old schematics in order to know what/how something did what it did.
Don't get me wrong. I have a dedicated space for electronics for the first time in my life and I think that's really nifty. Finally, I've got somewhere to stack all the stuff and junk and things and whatnots that I've accumulated over the years.
I was wasting space with a lot of pieces of equipment that I wanted to salvage gizmos from, but never seemed to get around to doing so. (We all know that John would never keep stuff like that, but I'll bet the rest of you know what I'm talking about.) A while back, I declared a "Melt-down day" whereupon I girded my loins and attacked all those space-wasters, thus producing a pretty hefty pile of refuse and an embarassingly small pile of goodies. (Oh, to think of the energy I wasted carrying that nonsense around over the years.) Once the junk was carted off, I had space to walk...for about a month. A few survivors of the first Melt-down day have since crept out of hiding. I'm piling them up. Their time is coming...just as soon as I change this diaper, finish the amp I'm working on, feed the twins, prototype the phono stage I've been scratching on paper for the last month, harvest the peppers...okay, so maybe those old circuits aren't exactly cringing in fear. They know full well that they've got at least another decade to live at the rate things are going.
If the small ziplock bags are what you want, let me know and I'll send you a zillion or so. My wife works at a locksmith's shop and they get scads of the things with keys, pins, screws, you name it in them. I'm currently using a few of them to hold my remaining stock of Lovoltech JFETs, so it's not as though I'm unacquainted with the concept. I just stick a scrap of paper in the bag with Vgs and quantity so I can keep track of stock. They just don't work so well when I'm in and out of the bags, actively messing with the parts. But for stock...oh yeah, they're great.

Old 25th September 2007, 04:20 AM   #2108
wrenchone is offline wrenchone  United States
diyAudio Member
wrenchone's Avatar
Join Date: Feb 2004
Location: Silicon Valley
My sorting jig ain't as pretty (?) as Mike's (a PCB with spacer legs), but it's the same general idea. I have 5 sockets, which cover all the Jfets and small signal Mosfets I'm inclined to use, with pin sockets to plug in a pair of DVMs for VGS and drain current. My jig runs off a pair of 9V batteries.

I used to match parts in advance according to IDSS, rope the parts together with tape, and mark the measured values on the tape. Now
I match on demand by starting with a pile of fets and a piece of paper. Each fet gets a space on the paper with measured VGS at the ID of interest, and I use this info to put pairs together. I generally won't accept a match looser than 0.010 volt. It helps that I don't have cats or kids....
Old 25th September 2007, 06:17 AM   #2109
jacco vermeulen is offline jacco vermeulen  Netherlands
diyAudio Member
jacco vermeulen's Avatar
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
A stack of paper envelopes, standing upright in a box of the same size, keeps them tidy and easy to catch.
The Idss number is written on the envelope and they're closed with a paperclip.

Glueing a piece of xerox paper on anti-static foam of the same size keeps the parts safe in position, piccy=>
Attached Images
File Type: jpg fetpuzzle2.jpg (57.1 KB, 853 views)
Old 25th September 2007, 04:38 PM   #2110
anatech is offline anatech  Canada
diyAudio Moderator
anatech's Avatar
Join Date: Jun 2004
Location: Georgetown, On
John Curl's Blowtorch preamplifier
Hi Jacco,
I do the same thing that you do, except that I put them in drawers. Large amounts go in a bag together (one number to bag) and I sit down and sort some every now and again. Works for me.

Hi Grey,
Obviously she hadn't priced parts drawers recently, which is fine as long as Nelson's buying. Even the cheap little P.O.S. 60 drawer units at Lowe's were over $20 the last time I priced them and that's been a couple of years.
Yes. This becomes a balance between how much your time is worth and what the parts are worth.

"Just because you can, doesn't mean you should" © my Wife

Closed Thread

John Curl's Blowtorch preamplifierHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

New To Site? Need Help?

All times are GMT. The time now is 02:42 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio