Simple Op-Amp Tester

[Ciaran Haslett]

I salvage op-amps from old electronics equipment and have built up quite a stash.  My only worthwhile means of testing them is to put them in a verified circuit and see if it works...but when you've a few hundred reclaimed IC's that take a long time.

Also, quite a few beginners don't have/use IC sockets and can run the risk of burning a chip.  The only real way for them to test it is to remove it, replace with another and hope for the best.  Many times they only have the one so using this could help identify other issues on a build.


NOTES

The IC's shown are representative of the ones you'll be testing.  The pads on the pins represent IC sockets.  It's the sockets you will be soldering in place as shown.
If your IC is well, the LEDs will light up.  If one doesn't, bad channel.
I'd recommend putting the 9V wire on a SPST toggle switch or momentary.  Hot swapping could cause failures
Single = TL061, TL071, LM741 etc
Dual = TL072, JRC 4558, NE5532 etc
Quad = TL074, TL084, LM348 etc
The 300Ω is the current limiting resistor for each LED.  Experiment with different values to taste.

Hope this is of use to someone.

Now VERIFIED

[kirshman]

That's awesome! Thanks for doing this!

[Suzukiscottie]

Nice one Ciaran!

I'll definitely use those for recovered op-amps too! Cheers!

[Marbles]

This is awesome, thanks!

[ξεναγος νεκροπολης]

top mate!!!
very usefull as i also salvage staff from old radios and mixers.
a few days ago i've pulled out 2 JRC4558 that looked really old, and haven't tested them yet.
i'll preadboard this tester asap!
lets see if there is a living myth in those JRC4558!!!

[Ciaran Haslett]

Great Savvas!

Let us know how it goes.  It's be a few days before I get a chance.

Here's the (very short) thread I found it in.  Not much info at all.

[Ciaran Haslett]

The joys of working in a college...when classes are on, I've nothing to do.Verified

Tested the dual version with a known working opamp and a known faulty one.  Lit up both channels on the good one and none at all on the dodgy one.  I see no reason why the single and quad versions shouldn't work.

Here's a pic on the breadboard...I followed the layout, not the schematic so layouts will be fine.  


The resistor values aren't that important as long as you keep the same divider ratio...I tried with a 12K and 6.8K (pictured) and got the same results.  And as I suspected...the 300Ω CLR is a bit small...my water clears are bright as hell!  I recommend upping to at least 470/820Ω or higher.

Anyway, I'm definitely building these into my test box...if I've any room left

[motterpaul]

Hey thanks. I really needed these. I built all three and the single and dual definitely work and can be verified. I did finish the quad but it did not work although that can still be user error. Everything looked good, but I did not do a lot of troubleshooting.

Yes - this is really important because I am finding that I do have some bad opamps - and that can be frustrating because you never know for sure when one goes bad

[Ciaran Haslett]

Glad you're getting some use out of them.  Bear in mind this is super basic.  It will tell you if an opamp channel works...but not how well/noise etc.  For that you'd need a oscope or at least a test audio circuit to audition IC's.  The layouts are good for quick "Keep/Bin" sorting.

As for the quad layout...it matches the the others so maybe a build issue...or it works and your quad IC actually dead

[reggy1]

The quad tester could be not working if you followed the layout 100%, motterpaul. The portion in the lower-left quadrant shows a 1K resistor instead of the 10K ones in each of the other quadrants. May be the cause? I've done the single and dual as well but haven't yet completed the quad.

[Ciaran Haslett]

Haha....spot on!  I was looking at the placement and did't even notice the values.  1K is my default value.  Must have overlooked it sorry.  I'll update later tonight at some stage.

Cheers

[motterpaul]

That is funny - I had posted mine was not working, BUT it was my fault. I was off a row because I thought dual opamps were 8 rows. It was not until I inserted one that I saw my mistake and realigned the whole board and then it worked fine, even with the 1k resistor.

In fact, either way you can call these verified.

[Ciaran Haslett]

Updated.  Cheers lads

[reggy1]

Hi Ciaran, have built single, dual and quad,and all work "as advertised". Thanks for the layouts.
Should this be in "Verified" now? Not sure of procedure here.

[Ciaran Haslett]

Yeah...one of the admins will move it when they see it.  Cheers Reggy

[tabbycat]

Ciaran Haslett wrote

The 300Ω is the current limiting resistor for each LED.  Experiment with different values to taste.

Hope this is of use to someone.

Now VERIFIED

many thanks for these layouts, ciaran. am just getting myself together re diy testing kit. fet, opamp, etc.

i've only got 330r or 2 x 150r in series for each of the various 300r. using the 330r would save me stiching reistors together (which i would prefer to avoid). am guessing they only effect the brightness of the led rather than being critical? 330r within 10% of 300r.

[Ciaran Haslett]

Yeah...just affects brightness.  I found mine very bright with 300r if I'm honest.  Maybe go higher.

Cheers

[tabbycat]

thank you for the confirmation, ciaran. am looking forward to trying these as i have a little pile of 'maybe' chips from builds that never worked that may be fried or fine.
will try a few between 330r and 1k. i use 1k in my stomps for brightness.

btw have you seen anything that does the inverse? that goes in the socket in place of a chip but does the same sort of instant diagnostic thing?

eg, something 8 or 14 pin that you can plug it into an ic socket in a layout and the lights come on (or don't) if those pins are getting enough power and are properly grounded to run a chip.

i know i can take readings of voltages easily enough, but i was thinking that something like that would speed up debugging as you could just fiddle around with a troublesome circuit (jumpering here, grounding there, etc) and see immediately (no stopping to take readings) what was going on in the ic socket.

that would be interesting. maybe these above builds could be tweaked to run in reverse or something?

[MAO]

Cool idea!

How could something similar be done to test a LM13700 ?

LM13700 Pinout

[Ciaran Haslett]

I think there would be too many variables in circuit design using pampas that it would be hard to come up with a "one size fits all" plug in solution tester.  The supporting circuitry is different from pedal to pedal, different uses for the IC (buffer, amplifier etc).  Then the loads both before and after the opamp affects the voltage you'll see on the pins  AND the socket measurements will look very different to measurements taken with an IC in circuit!

The only thing you can really do without the IC inserted is measure the supply/ground pins I think.  They would be the only pins with a consistent reading between IC in situ or not.  When I'm building a vero I always have my common probe on my DMM jammed into my test box ground point so I'm only fiddling with the positive probe.  Makes taking readings a lot less hassle but yeah...a quick plug in, lights on, everything grand tester would be great.