Handy little tester. I will build one. I will give the diode junction test a try as well as I have a bunch of used op amps here. Maybe I will figure out some specific charateristics. Another great educational and entertaining video from you. Many thanks!
I just measured through my old/used op amp stock. Most op amp read like a diode junction at the inputs and outputs. I tested it for CA082, CA3130, CA3140, JRC2904, JRC3404, LF357, LF411, LM318, LM358, LT1354, NE532, NE5532, NE5534, TL061. The LT1001 reads a little high on the inputs with just below 1V. Some behave totally different. The first group has a quite high reading at the output: TL082/TL074: read around 1,3V at the output (TL08x needs also a long time to settle for a stable reading) LM308: reads around 1,5V at the output The secound group reads open at the inputs: LM741/UA741/CA741/MC1741/MC1458 -> all 741er LM301 This way I found a suspicious NE5534 which is likely bad. I have to further test it.
Thanks, Richard. A fun and useful project. I breadboarded it first then out of curiosity took out the two diodes on the single tester and it continued to work. Perhaps the diodes just cancel each other out. Regards, Peter
I've built one of these opamp testers before and they are somewhat useful. The only thing I would change is to use a cheap ZIF socket instead of those standard IC sockets. It makes it much easier and faster to check opamps.
This circuit you rebuilt is simply a square wave oscillator using positive feedback to create hysteresis on the Vin+ input. FEATURES: That commercial tester is unique in a way: it “feels” the delay on the rise-time (or fall) of slower OpAmps (as LM358) usually employed as the base for faking faster ones as TL082/072: same pinout, but 20x faster than LM358. Detecting by Exclusive OR operation (description seen in your video) any delay from Input-Output, it confirms visually the delay and slower OpAmp. I believe it is an ingenious method to test slew rate and rise-time for large signals. LIMITATIONS: That circuit, however, does not test other features that are different for identification of wrong markings (LM358 x TL072), which may be important for user specific needs: (1) common mode input voltage range: GND to Vcc-1.5 (LM) versus GND-1.5 to Vcc (TL; rare feature for a jelly bean OpAmp). (2) crossover distortion (using sinusoidal/ triangular wave) - LM358 only. (3) increased output impedance - TL0xx only. SUPPLEMENTs: (1) Possible way to investigate that Ex-OR circuit would be to increase switching frequency, so that rise-fall time correspond to a higher percentage of the duty cycle. This will make the “Red LED” more visible. (2) Another possibility is to use Freq: 1KHz~5KHz and hear thru a small headphone speaker the Red LED output (AC buffered by a BJT).
Which just goes to prove that nothing will test every parameter of a component, but the tools are still useful in as much if they identify the chip as bad, it is definitely bad, if they identify it is OK it probably maybe is.
I can confirm that 3:28 - 2nd method works also with shift register IC. And I always make a chart for that component, so for later comparison I dont need component, I just need that chart. Also never bother to measure IC while in circuits, surrounding components will mess up results. Remove it and test. Small DIY testers are OK if you work in lab everyday, but if you are working on field then you have to learn to use multimeter for a lot of different things and develop way of thinking. @Learn Electronics Repair, there is one more topic to cover (if you didnt already) some basic shift register chips.
I would agree about in circuit testing not always being conclusive, but I can't think of any configuration of connected components that would cause the op-amp to read open circuit (or high resistance) where it should read a diode junction - as happened in this case. I'm also very suspicious of the low reading on pin 1 (output from op-amp A) as that also read open once i removed the chip from the board - I will investigate what causes the low reading on the PCB
The diode drops seem are i expect the ESD protection, there is a chance that there is some also connected to the Vcc pin as well. Just measuring the diodes only shows that there is still a connection to the silicon inside, not that the chip will function as it should. this is the type of thing a flying finger PCB tester does, it can't test the components but it can check that pin is connected to the PCB track. The tester is just making the opamp an astable oscillator. So a bit crude but it will need to have most functionality intact to flash the LED's so ok as a basic tester.
is it possible to test simply the health of a dual op amp in circuit ? with a multimeter ? it's an SMD, and i don't have the means and tools to unsolder and resolder it.
Hi Richard, Firstly this video is enormously informative. I am taking my first steps into electronic repairs. I hope you notice and read my question. The BA4560 op amps, where did you order yours from ? I have found a few sources for them, but the codes on them seem slightly different. Some have an extra letter eg - BA4560N or whatever. What does this mean ? Will they do the job. I'm hoping to repair an old 12 input Studiomaster mixer with some faulty channels. Could fitting a chip with this slightly different code or another 'more modern equivalent' result in the repaired channels behaving/sounding different to the others ? If they are cheap would it be prudent to just change out all of them ? ( plug in type ) If anyone else reading this could help, please do comment. Regards, John Nottingham UK
I would to ask how Diode mode works? does the multimeter inject 3 dc volt across the I.C. terminals and the multimeter reads the voltage drop between the two pins ?
Basically yes - sometimes more that 3V, near to 4V. The meter acts as a low power constant current source, so you read the voltage dropped across the device under test. It works in a similar way to my $1 short finder but with less current. ruclips.net/video/0eixDdCpiO4/видео.html
Nice tester. Would your Huntron Tracker Octopus PCB Tester that you showed in one of your other videos be a better way of testing the op-amp in circuit?
Hi Rich , another great project. How about building a usb port tester for voltage and data indication Useful testing laptop with black screen They cost 50 euros so very expensive for a simple circuit..one for the future??
Handy little tester. I will build one. I will give the diode junction test a try as well as I have a bunch of used op amps here. Maybe I will figure out some specific charateristics. Another great educational and entertaining video from you. Many thanks!
I just measured through my old/used op amp stock. Most op amp read like a diode junction at the inputs and outputs. I tested it for CA082, CA3130, CA3140, JRC2904, JRC3404, LF357, LF411, LM318, LM358, LT1354, NE532, NE5532, NE5534, TL061. The LT1001 reads a little high on the inputs with just below 1V. Some behave totally different.
The first group has a quite high reading at the output:
TL082/TL074: read around 1,3V at the output (TL08x needs also a long time to settle for a stable reading)
LM308: reads around 1,5V at the output
The secound group reads open at the inputs:
LM741/UA741/CA741/MC1741/MC1458 -> all 741er
LM301
This way I found a suspicious NE5534 which is likely bad. I have to further test it.
@@UltraUltaderdritte Thanks for the info *Pinned*
Thanks again mate! As I had all the parts, I made one along with your video, along with many, many pauses and rewinds! Cheers, Darren
Thanks for the handy Multimeter OPAMP test!! Very helpful, and easy!
the new camera setup is nice
Thanks, Richard. A fun and useful project. I breadboarded it first then out of curiosity took out the two diodes on the single tester and it continued to work. Perhaps the diodes just cancel each other out. Regards, Peter
I've built one of these opamp testers before and they are somewhat useful. The only thing I would change is to use a cheap ZIF socket instead of those standard IC sockets. It makes it much easier and faster to check opamps.
Very helpful. Thank you for providing such a hands on, no frills demo. 🤙
This video was so much help to me. Brilliant.
Awesome!! thanks
This circuit you rebuilt is simply a square wave oscillator using positive feedback to create hysteresis on the Vin+ input.
FEATURES:
That commercial tester is unique in a way: it “feels” the delay on the rise-time (or fall) of slower OpAmps (as LM358) usually employed as the base for faking faster ones as TL082/072: same pinout, but 20x faster than LM358. Detecting by Exclusive OR operation (description seen in your video) any delay from Input-Output, it confirms visually the delay and slower OpAmp. I believe it is an ingenious method to test slew rate and rise-time for large signals.
LIMITATIONS:
That circuit, however, does not test other features that are different for identification of wrong markings (LM358 x TL072), which may be important for user specific needs:
(1) common mode input voltage range: GND to Vcc-1.5 (LM) versus GND-1.5 to Vcc (TL; rare feature for a jelly bean OpAmp).
(2) crossover distortion (using sinusoidal/ triangular wave) - LM358 only.
(3) increased output impedance - TL0xx only.
SUPPLEMENTs:
(1) Possible way to investigate that Ex-OR circuit would be to increase switching frequency, so that rise-fall time correspond to a higher percentage of the duty cycle. This will make the “Red LED” more visible.
(2) Another possibility is to use Freq: 1KHz~5KHz and hear thru a small headphone speaker the Red LED output (AC buffered by a BJT).
Which just goes to prove that nothing will test every parameter of a component, but the tools are still useful in as much if they identify the chip as bad, it is definitely bad, if they identify it is OK it probably maybe is.
shhht... these things are not simple....
I can confirm that 3:28 - 2nd method works also with shift register IC. And I always make a chart for that component, so for later comparison I dont need component, I just need that chart. Also never bother to measure IC while in circuits, surrounding components will mess up results. Remove it and test. Small DIY testers are OK if you work in lab everyday, but if you are working on field then you have to learn to use multimeter for a lot of different things and develop way of thinking. @Learn Electronics Repair, there is one more topic to cover (if you didnt already) some basic shift register chips.
I would agree about in circuit testing not always being conclusive, but I can't think of any configuration of connected components that would cause the op-amp to read open circuit (or high resistance) where it should read a diode junction - as happened in this case. I'm also very suspicious of the low reading on pin 1 (output from op-amp A) as that also read open once i removed the chip from the board - I will investigate what causes the low reading on the PCB
Another great video, simple and effective tester.
The diode drops seem are i expect the ESD protection, there is a chance that there is some also connected to the Vcc pin as well. Just measuring the diodes only shows that there is still a connection to the silicon inside, not that the chip will function as it should. this is the type of thing a flying finger PCB tester does, it can't test the components but it can check that pin is connected to the PCB track.
The tester is just making the opamp an astable oscillator. So a bit crude but it will need to have most functionality intact to flash the LED's so ok as a basic tester.
squeak !
Great video dicky, also the new webcam is awesome, keep up the great work mate 🤙🏼🇦🇺
Upps... burned. Super camera. (From Germany)
is it possible to test simply the health of a dual op amp in circuit ? with a multimeter ? it's an SMD, and i don't have the means and tools to unsolder and resolder it.
Hi Richard, Firstly this video is enormously informative. I am taking my first steps into electronic repairs. I hope you notice and read my question. The BA4560 op amps, where did you order yours from ? I have found a few sources for them, but the codes on them seem slightly different. Some have an extra letter eg - BA4560N or whatever. What does this mean ? Will they do the job. I'm hoping to repair an old 12 input Studiomaster mixer with some faulty channels. Could fitting a chip with this slightly different code or another 'more modern equivalent' result in the repaired channels behaving/sounding different to the others ?
If they are cheap would it be prudent to just change out all of them ? ( plug in type )
If anyone else reading this could help, please do comment.
Regards, John Nottingham UK
The final letter usually indicates the form factor of the chip, eg 4560D is dual row through hole if I'm correct.
Can you test LM741 using the reverse voltage multimeter method? Or is it just JFET input Opamps?
In what setting is the multimeter on to check op amps?
Can i apply this circuit on 4558 ic
I would to ask how Diode mode works? does the multimeter inject 3 dc volt across the I.C. terminals and the multimeter reads the voltage drop between the two pins ?
Basically yes - sometimes more that 3V, near to 4V. The meter acts as a low power constant current source, so you read the voltage dropped across the device under test. It works in a similar way to my $1 short finder but with less current.
ruclips.net/video/0eixDdCpiO4/видео.html
Looks like an astable or monostable cct doesn't it, but with an op amp rather than 2 transistors?
Thank you
Could you do a video showing how to test OTA ICs like a ca3080? Thx for all the great videos.
Nice tester. Would your Huntron Tracker Octopus PCB Tester that you showed in one of your other videos be a better way of testing the op-amp in circuit?
Yes quite possibly - I'll play around with that when I get chance
The thing with ali express sometimes it's an imposter ic it seems. Hit and miss, or the number will arrive one letter different than advertised.
Nice !....cheers.
Hi Rich , another great project.
How about building a usb port tester for voltage and data indication
Useful testing laptop with black screen
They cost 50 euros so very expensive for a simple circuit..one for the future??
I have a commercial one coming to review - after that we could look at building a home made one 😉
New cameras great
LM358 on left looks counterfeit.
Too long. That is why I put dislike. 10 or maximum 15 minutes should be standard.