Simple Op Amp Tester Circuit.

217

03:06:18

This is one I've built on protoboard. I built it with sockets to test single, dual, or quad op amps. The circuit simply shows that each op amp is functional, and has gain on each stage. I'm using a +/-5 volt dual polarity supply to power the circuit. For the purpose of this specific simulation there is no reason to have 4 stages modeled. I have been using the 4 stages to look at other configurations privately.
  The circuit I built powers all 4 stages just like the simulation. I built this using cheap 5×7 perfboard. I built it to fit inside an old laptop power brick enclosure. In order to fit it inside the enclosure I used 2 perfboards stacked on top of each other and cheap pin headers to attach them. The lower board has most of the wire connections while the upper board uses mostly bus wire and solder traces. Why tell you all of this? Because I'm working on a YouTube video about this device now, but the necessary information needed to build the circuit are already posted on my GitHub account. I created a full schematic on KiCAD and then used PCBnew to create a model of the perfboard layout and wiring. Anyone that is reasonably intuitive should be able to create this from the files I have provided.
https://github.com/Upcycle-Electronics/OpAmpTester
  I haven't decided if I want to create a video about it sooner by making it about the current device or if I want to revise the design and create a full video of the build. The current device is pretty sloppy and built from my junk box. Things like the LED's are all different brightnesses etc.

Note:
  The idea of placing a second LED on the output to test an op amp's ability to sink current, and also the idea for the adjustable potentiometer configuration were contributed by Rich below. (Thanks)

I'm a simple hobbyist that got into electronics after becoming partially disabled a few years ago. I like to share and create content about some of the things I've learned. I make lots of mistakes. My YT channel is not monotized, and I don't plan to make it monotized. I can't upload regularly in my condition and I'm not interested in adwhoring for a dollar or two. To me, YT is just another source of information and a place to explore the hobbyist community.
-Jake
YouTube.com/UpcycleElectronics

published 7 years ago

hurz

7 years ago

You have to change the test voltage at this negative gain -15/2.2=-6.82 which would give +34.09V by -5V input. The OpAmp's are all clipping. Out of range. Anyway, quite static your test, and source current proofs nothing about sink ouput current. There are many more parameter to test and hope its fine in total! Start with a single OpAmp to understand better.

j4k3

7 years ago

Thanks for the feedback. Its just the circuit from here: https://tangentsoft.net/elec/opamp-tester.html

j4k3

7 years ago

I have one of the cheap little volt/current meters from China that I think has a bad LM358 op amp. The current shunt circuit is grounded to the voltmeter side of the circuit and I've tried everything else. I just wanted a way to test the most basic functionality of an op amp. Maybe I'll get the chance to learn more and build something more functional as I need it.

j4k3

7 years ago

NM I see my mistake on here now. It's been corrected. The 2K2 was supposed to go to ground instead of the negative rail. I did the schematic from memory to waste time waiting on something else. Should have double checked before making it public.

rich11292000

7 years ago

Use the potentiometer to change from source to sink. http://everycircuit.com/circuit/5506166624092160 and tidy up the mess.

hurz

7 years ago

@j4k3, dont you think three of the OpAmp circuits can be removed to not let it be so messy. Would extremly help to have an better overview for you and avoid such misstakes.

j4k3

7 years ago

Thanks for the suggestion. I'm using this circuit to look for minor changes I can make with push buttons to change a resistor value or cascade stages to test different op amp specs. This sim is just the foundation. I thought others might find this helpful as well. I could be wrong.

j4k3

7 years ago

oh wow Rich!! Thanks for that circuit. I'm going to try that modification. It took me a bit to figure out how to see that link by copying and searching the circuit number in the app. I don't have a handy desktop computer, just a clunky old laptop. The EC website doesn't work on my Android phone plus I'm not very familiar with this app. It's just more convenient than opening LT Spice. Thanks again,

hurz

7 years ago

I took the beautiful version from rich. You see what I mean. Why do you try to test 4 opamps in parallel? Is it that you are going into mass production?

hurz

7 years ago

Here we go http://everycircuit.com/circuit/6239877900533760

j4k3

7 years ago

@Hurz Thanks. I am building this as a tester circuit tool. I need all 4 op amp circuits to test quad package op amps. I've also added the sockets for single and dual package op amp IC's with all 3 in parallel with each other. I've been playing around with different configurations in this simulation to see the effects. I still do dumb things like trying to place 1 resistor for limiting the current to all LED's instead of 4. I'd much rather figure out it's a dumb idea in a simulation before building it. I'm sorry if it bothers you that I uploaded such a mess. You guys can do whatever you want with it. I'll make it private if you want me to. I don't really care. I found the circuit to be helpful, so I shared it as such.... The link is the 3x configuration, it's nothing fancy. Just a bunch of lifted pads on the other side of this junk protoboard after I've tried to add Rich's suggestion :) https://drive.google.com/file/d/1wwRn766Uza9f8sCKUBg9kgD_21KjGQ63/view?usp=drivesdk

rich11292000

7 years ago

Nobody will ever learn if you keep everything private, this is a good idea, and we all made it better. Thanks to Hurz, follow his schematic, my circuit was just goofing around until it worked.

hurz

7 years ago

We understand that you have basic problems with OpAmps and electronics, cause you are a newcomer. Thats ok and absolut no problem. But what i dont get is, if you have already trouble with one OpAmp why are you quadruple your problem only your final layout on PCB does contain 4 OpAmps? Why do you make it extra obfuscated if you only need to understand the function of one item? BTW, this doesn't make this circuit absolut not more attractive. And if you realy want to see the effect of 4 in simulation, then there is a little trick which you can make to simulate 100 opamps in parallel, cuz they do all the same. But before you have to understand the function of just 1. Enough said to this topic. Keep it up.

j4k3

7 years ago

Thanks Rich, your input and positive comments really help. I like the source/sink idea. The potentiometer threw me off at first, as this was intended as a 'go/no-go' circuit, but after goofing around with it I see the extra functional potential. My plan for wiring got a bit messy on the proto board after moving the LEDs around so I've added headers and a second layer of protoboard. Now I have the added benefit of being able to remove this feedback circuit as a module and plug in a replacement later if I want to reconfigure. If you hadn't suggested the source/sink bit I would have never thought to build it like this. Thanks again, -Jake ;)

hurz

7 years ago

@j4k3, por nada, thanx for your attention and credit, LOL.

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