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Old 7th Jan 2019, 1:28 pm   #1
M3VUV51
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Default Op Amp test jig.

Hi all, does anyone know of plans for a DIY Op Amp test jig? A sort of go/no go tester. I have a few to check.

Regards M3VUV 73.
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Old 7th Jan 2019, 1:33 pm   #2
Ted Kendall
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Default Re: op amp test jig

One of those little Chinese chip testers you can get on auction sites would do the job.
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Old 7th Jan 2019, 1:37 pm   #3
Terry_VK5TM
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Default Re: op amp test jig

Elektor Electonics did a diy jig in March 2005 page 74.

Pretty sure most of the electronics mags have done one at some time in the past.
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Old 7th Jan 2019, 2:37 pm   #4
David G4EBT
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Default Re: op amp test jig

I built a simple op-amp tester many years ago which I've just dug out of a drawer. I was horrified when I opened it up, to find that it was way back in 1995 when I built it! I was even more horrified to see that I must have knocked it up in a hurry on a piece of scrap vero-board, mounted in a tatty ABS box, with a Dymo label on it. But it works and I guess that's what matters most. Functional if nothing else. Heaven knows how long the battery has been in it.

Inside the box is a wonky label which states that it was from a Babani Book - 'All about Op-Amps' otherwise I'd have had no clue as to where the circuit was from. I've found the book and scanned the article, which I've appended below. Not much to say about it really. I've since built a 555 tester and both work on the same principle - plug in the IC under test, press the momentary push button and if the IC is good, the two LEDs flash at intervals. I guess that nowadays, I'd be tempted to add an output socket to see the waveform on the 'scope, but maybe that's a step too far.

Hope that helps a bit.
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Old 7th Jan 2019, 4:12 pm   #5
julie_m
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Default Re: Op Amp test jig.

That's using rather a lot of parts just to do something so simple!

I'd have used the op-amp itself as the oscillator, and then all the test box really need contain apart from the battery and "test" switch is a handful of passives. Bonus points if you replicate the circuit another three times and use two 8-pin and one 14-pin chip sockets, so you can test an entire 324 in one go -- or a 5534 and a 5532 simultaneously!
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Old 7th Jan 2019, 4:45 pm   #6
M3VUV51
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Default Re: Op Amp test jig.

Spot on, cheers all.
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Old 7th Jan 2019, 4:59 pm   #7
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Default Re: Op Amp test jig.

Quote:
I'd have used the op-amp itself as the oscillator
An elegant solution, maybe a slow oscillator with a buffered LED to show the rising and falling waveform.
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Old 7th Jan 2019, 5:01 pm   #8
Philips210
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Default Re: Op Amp test jig.

Hi.

You could also mount the 555 timer IC and socket on the front of the box to check these as another option.

Regards
Symon.
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Old 7th Jan 2019, 6:01 pm   #9
David G4EBT
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Default Re: Op Amp test jig.

Quote:
Originally Posted by Philips210 View Post
Hi.

You could also mount the 555 timer IC and socket on the front of the box to check these as another option.

Regards
Symon.
True enough. I made a separate 555 tester back in 2015 as I'd been given a lot of 555s of unknown provenance.

Just four resistors, two caps, two diodes and a push button.

As it happened, all the ICs were good when tested. It's a long time since I built anything on strip-board so I designed a little PCB for it, but for anyone not so inclined, it's so simple that it could be made on perfboard and not boxed up. I spaced the PCB on pillars below the front panel and used a little 'tower' of IC sockets pushed together, with the top one fixed to the front panel with epoxy. (The PCB artwork in pic 3 is shown 'flipped' so could be used for the laser printer 'iron on' technique).

Not directly relevant to this thread, but it might be of interest.
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Old 7th Jan 2019, 7:20 pm   #10
Philips210
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Default Re: Op Amp test jig.

Hi.

That's another useful project in a professionally made box. When I build a 555 tester, I might add a pot to alter the frequency and have some test points to connect to the oscilloscope. I like the idea of the stacked IC sockets, they look like the better quality turned pin type.

Regards
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Old 9th Jan 2019, 11:13 pm   #11
calicobramble
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Default Re: Op Amp test jig.

Back in the day RS offered little test pcb's for 741's and 555's. I don't have the part numbers to hand, but they are obsolete anyway. I have however seen the same sort of thing advertised on ebay.

I've used these to check if the centipedes in my bit box are still alive. For the 741 just inject a signal and see if it comes out OK on a scope; for a 555 you just need the scope,

Best rgds Simon
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Old 16th Jan 2019, 10:50 pm   #12
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Default Re: Op Amp test jig.

I bought a small 'Raaco' cabinet with plastic drawers full of components from one of the Yeovil 'QRP' amateur radio sales, -probably from a 'Silent Key' clear out I expect.

Included in one of the drawers were packets of the RS pcbs noted by Calicobramble above: Stock no. 434-071 for the 555 Timer board and 434-065 for the 741 Operational Amplifier. Component placings other than the IC itself are noted as R [or C] suffix 'a', 'b' or 'c' so the user would select absolute values to suit the required application.

Another drawer contained examples of RS Stock number 305-478, 'Integrated Circuit Timer', aka the 555 to go with the pcbs, [although the DIL package itself is just labelled "RS Timer A". Each component was in an individual cardboard box and with a
printed data sheet giving formulae to calculate the 'R' and 'C' values for use with Monostable or Astable applications.

How times have changed!
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