It's specified at ±15V (which was the standard op amp supply voltage at the time the 741 was designed) but will likely work down to ±10V or less with possible reduced performance.

And this chip is spec'ed for source of up to +/-22V, which I did try as well.

 

Hello,

Are you sure about the ±22 Volts?

Bertus

 

You don't want to operate a chip at its Absolute Maximum Limits.

 

1) Do you have a photo of your build of the test circuit? I know you've probably checked, but when the laws of physics seem to stop functioning in my own work, it's usually because *I* did something wrong, not the universe!

2) What is the frequency of your input signal?

 

1) Do you have a photo of your build of the test circuit? I know you've probably checked, but when the laws of physics seem to stop functioning in my own work, it's usually because *I* did something wrong, not the universe!

2) What is the frequency of your input signal?

I do not have a photo of the circuit, but I have rebuilt it several times for that very reason, double checking pins, connectivity between points on the breadboard and etc. I, too, usually assume it's something I did wrong and I double or triple check everything before I start asking questions. I also know it's really hard to analyze someone else's circuit, so I typically just start over if I suspect I connected something wrong.

I have changed the frequency, just to be sure that it wasn't too fast to respond or something. I started out at 1 kHz, but then have ended up working at 1 Hz so I could double check the input on the board with a diode. The input is fine, but still no output (as monitored by a diode, a DVM, or an oscilloscope).

 

Check the breadboard. Often the "power/ground" lines on the sides set into two halves. There is usually extra space in the middle to separate/mark the two halves. So you might be running power from one half, ground from another half and think that everything is connected, but in reality it is not and this missing connection is not visible to you the user.

 

Check the breadboard. Often the "power/ground" lines on the sides set into two halves. There is usually extra space in the middle to separate/mark the two halves. So you might be running power from one half, ground from another half and think that everything is connected, but in reality it is not and this missing connection is not visible to you the user.

I hate to even admit how many times I've done this...

 

I hate to even admit how many times I've done this...

You should have seen me in my second year circuits lab. The first time I ran into that, I was ready to tear my hair out. But that was first and last time I made that mistake.

 

I'm pretty new to this too, but couldn't he just set up the 741 as a voltage follower to test the chip?

 

Hello,

The LM741 is a very old opamp.
As the output will not go rail to rail, the results can be disappointing.

Better choose one from this table:

Op Amp - Single Supply, Rail-to-Rail|Opamps|Slew Rate V/us|GBWP MHz|Ios pA|Vos uV|Idd uA |Vdd V
LM7332 |2|15.2|21|1000|2000|2000|2.5-32
OP295 |2|0.03|.075|7000|300|175|3-36
OP495 |4|0.03|.075|7000|300|175|3-36
TLV2252 |2|0.12|0.20|1|200|68|2.7-16
TLV2254 |4|0.12|0.20|1|200|68|2.7-16
TLV2262 |2|0.55|0.71|1|300|400|2.7-8
TLV2264 |4|0.55|0.71|1|300|400|2.7-8
TLV2450 with shutdown|1|0.11|0.22|300|20|35|2.7-6
TLV2451 |1|0.11|0.22|300|20|35|2.7-6
TLV2452 |2|0.11|0.22|300|20|70|2.7-6
TLV2453 with shutdown |2|0.11|0.22|300|20|70|2.7-6
TLV2454 |4|0.11|0.22|300|20|140|2.7-6
TLV2455 with shutdown|4|0.11|0.22|300|20|140|2.7-6
TLV246x as TLV245x|1,2,4|1.6|6.4|5|150|550|2.7-6
TLV247x as TLV245x|1,2,4|1.5|2.8|2|250|600|2.7-6
TLV277x as TLV245x|1,2,4|10.5|5.1|2|360|1000|2.5-6

Bertus

 

Hello,

The LM741 is a very old opamp.
As the output will not go rail to rail, the results can be disappointing.

Better choose one from this table:

Op Amp - Single Supply, Rail-to-Rail|Opamps|Slew Rate V/us|GBWP MHz|Ios pA|Vos uV|Idd uA |Vdd V
LM7332 |2|15.2|21|1000|2000|2000|2.5-32
OP295 |2|0.03|.075|7000|300|175|3-36
OP495 |4|0.03|.075|7000|300|175|3-36
TLV2252 |2|0.12|0.20|1|200|68|2.7-16
TLV2254 |4|0.12|0.20|1|200|68|2.7-16
TLV2262 |2|0.55|0.71|1|300|400|2.7-8
TLV2264 |4|0.55|0.71|1|300|400|2.7-8
TLV2450 with shutdown|1|0.11|0.22|300|20|35|2.7-6
TLV2451 |1|0.11|0.22|300|20|35|2.7-6
TLV2452 |2|0.11|0.22|300|20|70|2.7-6
TLV2453 with shutdown |2|0.11|0.22|300|20|70|2.7-6
TLV2454 |4|0.11|0.22|300|20|140|2.7-6
TLV2455 with shutdown|4|0.11|0.22|300|20|140|2.7-6
TLV246x as TLV245x|1,2,4|1.6|6.4|5|150|550|2.7-6
TLV247x as TLV245x|1,2,4|1.5|2.8|2|250|600|2.7-6
TLV277x as TLV245x|1,2,4|10.5|5.1|2|360|1000|2.5-6

Bertus

I appreciate your research in this, but despite it's limited capabilities, I can buy them at $0.40 ea or cheaper. This is ideal for students who have little to no experience building circuits, especially on a breadboard. If they fry them (or if I do, which I have) we will not be wasting money. Also, they will be working with them for one day and then no one will touch them for another year. If I ever have a student that wants to build a real device, we will of course buy a more robust chip.

 

I have worked on old MXR guitar pedals where 741's are running on 9V (essentially +/-4.5V) and being used as relaxation oscillators, which means they're outputting square waves as close to the rails as they can. The device may not be operating in ideal circumstances, at that point, but it doesn't just sit there doing nothing.

Very old 741's can age and fail to amplify sometimes, but I have *never* seen a modern-manufacture device just quit without significant abuse, let alone a whole batch of them.

I STRONGLY suspect either an error in wiring or something about the layout is wacky (ie, breadboard power rails don't go all the way across, etc.). Regardless, extra eyeballs are the best medicine. I can't see this thread making any more headway without a picture of an actual build of the circuit.

 

I have worked on old MXR guitar pedals where 741's are running on 9V (essentially +/-4.5V) and being used as relaxation oscillators, which means they're outputting square waves as close to the rails as they can. The device may not be operating in ideal circumstances, at that point, but it doesn't just sit there doing nothing.

Very old 741's can age and fail to amplify sometimes, but I have *never* seen a modern-manufacture device just quit without significant abuse, let alone a whole batch of them.

I STRONGLY suspect either an error in wiring or something about the layout is wacky (ie, breadboard power rails don't go all the way across, etc.). Regardless, extra eyeballs are the best medicine. I can't see this thread making any more headway without a picture of an actual build of the circuit.

Well I got the TI chips today and plugged them in a comparator circuit and I'm getting amplification that is dependent on the source power (as close to the rails as possible, I tried 12-18V) and not the input (~100mV). I am still getting dissipation from edge to edge, but I think that has something to do with the capacitors in the inverter circuit. Once I got that running, I pulled out an old chip at random (one that I had not previously used) and there was NO output whatsoever. This is consistent with what I was seeing last week.

I didn't have a lot of time to play with it this afternoon but I'll be working on it tomorrow. I will try to get a pic of it up then.