Couple of things i need - Page 1
Forum section: electronics / beginners

author: p.larner
author_rank: Frequent Contributor
timestamp: March 22, 2024, 01:25:39 am
content: First off i need to get a 1v supply to calibrate a meter so only a ma or less,also need a tester for testing dual and single opamps,any ideas,links to schematics etc?.

author: tggzzz
author_rank: Super Contributor
timestamp: March 22, 2024, 01:32:00 am
content: Quote from: p.larner on March 22, 2024, 01:25:39 amThere are plenty of threads on this site and google will find you many more.Possibly the simplest is a saturated Weston standard cell, 1.018V

author: Smokey
author_rank: Super Contributor
timestamp: March 22, 2024, 02:04:38 am
content: Quote from: tggzzz on March 22, 2024, 01:32:00 am... ha!... funny story. A while back I bought a Weston cell off ebay and when it got here I immediately regretted it. Since it was shipped UPS it's probably shaken up beyond repair. So now I have a paperweight full of mercury and cadmium. I can't even imagine the looks I would get if I took that thing to the hazardous materials disposal site to try to get rid of it..... I highly recommend NOT buying a Weston cell.

author: tggzzz
author_rank: Super Contributor
timestamp: March 22, 2024, 08:30:56 am
content: Quote from: Smokey on March 22, 2024, 02:04:38 amI have two, one dated 1949. Both workNo, I didn't pay for them, but neither did I get them to pay me to take them away.More surprisingly, I've recently found a working unsaturated cell. It was in a nixie DVM that used a neon bulb as its voltage reference. There was a front panel control that allowed the reading to be adjusted until it read 1.019V

author: tooki
author_rank: Super Contributor
timestamp: March 22, 2024, 08:57:05 am
content: Quote from: tggzzz on March 22, 2024, 01:32:00 amI thought that connecting one of those to a multimeter ruins it? (Only an electrometer, with its huge input impedance, won’t damage it, as I understand.)

author: tggzzz
author_rank: Super Contributor
timestamp: March 22, 2024, 09:37:06 am
content: Quote from: tooki on March 22, 2024, 08:57:05 amThat is indeed the case. The standard cell (in the Solartron LM140 voltmeter/counter(!)) was only connected occasionally, and there was a front panel control that allowed the input current to be zeroed. Unsurprisingly you zeroed the current before setting 1.019V

author: jpanhalt
author_rank: Super Contributor
timestamp: March 22, 2024, 10:22:04 am
content: Quote from: Smokey on March 22, 2024, 02:04:38 amMay depend on where you are. I started collecting mercury a long time ago (before high school) and ended up with quite a flask full. Took it to my local hazardous waste center in NE Ohio (Lorain County), and it was happy to take it. Used mercury has a legitimate market, but as an individual, you are better off just giving it to a commercial recycler.

author: Majorassburn
author_rank: Regular Contributor
timestamp: March 22, 2024, 02:26:13 pm
content: Quote from: p.larner on March 22, 2024, 01:25:39 amI can build you one, good to four zeroes after decimal (1.0000) and maybe even more, run by on-board 15V regulated supply, free re-cals you pay postage, based on LT1236A and trimmed to perfection. Here's a sample link:https://www.ebay.com/itm/285759582505Tester for op-amps? What kind of tests? Maybe I can help there, too.email me at: sqwarrel@gmail.com if I can help you.

author: tggzzz
author_rank: Super Contributor
timestamp: March 22, 2024, 02:37:14 pm
content: Quote from: Majorassburn on March 22, 2024, 02:26:13 pmIn this threadhttps://www.eevblog.com/forum/buysellwanted/fs-diy-calibration-devices-(ac-dc-ohms)/msg5228793/#msg5228793you claim you are happy to answer questions - and then don't.Here are the basic questions again...What is your device adjusted against (i.e. type and its calibration status)?How long is the burn-in period?What is the guaranteed 90 day and 1 year performance? Under what conditions, e.g. shock, temperature, power cycling?

author: Gyro
author_rank: Super Contributor
timestamp: March 22, 2024, 03:55:41 pm
content: I fear the answers may disappoint...https://www.eevblog.com/forum/testgear/decided-to-buy-brymen-869s-help-me-avoid-buyers-remose/

author: tggzzz
author_rank: Super Contributor
timestamp: March 22, 2024, 05:13:38 pm
content: Quote from: Gyro on March 22, 2024, 03:55:41 pmTee heeThanks for the heads up and thumbs down

author: dobsonr741
author_rank: Frequent Contributor
timestamp: March 22, 2024, 05:20:32 pm
content: Why do you need an opamp tester? If you have a concern, better to buy a fresh new opamp, instead building a tester. Just a thought.

author: tggzzz
author_rank: Super Contributor
timestamp: March 22, 2024, 05:25:46 pm
content: Quote from: dobsonr741 on March 22, 2024, 05:20:32 pmThe chain of "reasoning" is probably...this isn't working as I expectit wouldn't work if the opamp was faultytherefore I must test the opamp to see if it is faulty and/or select the best opamp

author: Majorassburn
author_rank: Regular Contributor
timestamp: March 22, 2024, 06:01:18 pm
content: QuoteIn response to your concerns:1) I answered here because the OP posted in the BEGINNERS forum, not the Metrology Volt-Nut forum. Since it is a beginners forum question, your volt-nut concerns probably wouldn't apply to beginners, right?2) If you view my listing that I linked to, it clearly may be adequate for a beginner but not a volt-nut or Metrology product.3) Your pattern of posts and replies in various threads indicate that you have a somewhat negative and hyper-critical tone toward what you may consider to be, in your view, less-than-satisfactory participation by certain forum members. Some might categorize you as being arrogant to the degree of trolling for an argument or some such. That's not what most of us are here to engage in.4) My answers to your re-posted questions that you dredged up from a dead thread are as follows:QuoteFor $25-$30, no reasonable or serious-minded volt-nut would consider buying one of my devices for the kind of purposes that you are obviously referring to.So, why do you try to provoke hard feelings or try to encourage misunderstandings as you insinuate that, somehow and repeatedly, I am misrepresenting my devices?As I said in previous threads, these devices are offered for hobbyists and DIYers and are aimed at limited, low-cost functional checking of DMM's and are not intended to substitute for high-level calibration.I know from reading some of your replies that you are a capable of contributing valuable and helpful information to this forum so, tell me what I can do differently to help you re-orient yourself to move in that direction?Major.

author: Majorassburn
author_rank: Regular Contributor
timestamp: March 22, 2024, 06:02:16 pm
content: Quote from: Gyro on March 22, 2024, 03:55:41 pmYou, too.Same reply.

author: Smokey
author_rank: Super Contributor
timestamp: March 22, 2024, 06:28:11 pm
content: Come on guys! OP needs your help, so stop squabbling! Let's get back to talking about Weston cells!

author: Majorassburn
author_rank: Regular Contributor
timestamp: March 22, 2024, 06:35:56 pm
content: Quote from: Smokey on March 22, 2024, 06:28:11 pmOK, I'm on board. I like the old Clark cell better! Of course, with either cell, when your done with it and want to pour out all that toxic waste, you'll have enough mercury to make dozens of thermometers, right?

author: ArdWar
author_rank: Frequent Contributor
timestamp: March 22, 2024, 09:05:43 pm
content: Quote from: p.larner on March 22, 2024, 01:25:39 amOh come on now. As usual this kind of discussion will inevitably devolve into pissing contest shitpost if you don't even specify what you need. For all we know you might want to calibrate a 3458 or something.For a starter, what model of meter to calibrate? What level of accuracy do you need?What kind of meter even accept 1V calibration? Quite unusual value to be used on its own.For the second part, what parameter to be tested? I don't think there's one fits all tester. Most of us do application specific part qualification when needed.

author: p.larner
author_rank: Frequent Contributor
timestamp: March 23, 2024, 05:37:59 am
content: its for this boatanchor ,the opamp tester is to replace a simple flash tester i built and lost.

author: ebastler
author_rank: Super Contributor
timestamp: March 23, 2024, 05:55:31 am
content: Quote from: p.larner on March 23, 2024, 05:37:59 am3.5 digits is a modest precision requirement. Wouldn't you be better off buying a modern 4.5 digit multimeter and use that to calibrate the vintage one? It would let you calibrate all ranges quickly, and may also come in handy for troubleshooting or component-checking in the old meter.

author: p.larner
author_rank: Frequent Contributor
timestamp: March 23, 2024, 10:38:41 am
content: i already have a fluke 83+ a dmm on my tek 465 scope,its the voltages i need to feed into the meter to set the cal pots.