Sandelinos
Just did some testing and confirmed that every "TL072" and "TL074" I used during my first few years of building my synthesizer were actually relabeled LM356/LM324 chips. Never buy cheap ICs from ebay and aliexpress if you can avoid it. #SynthDIY #electronics
Mar 10 at 10:03pmWeb
Show threadSandelinosMar 10

To be fair they have been working ok, the input impedance, slew rate and distortion are just worse than TL07x.

The LM3xx opamps also have some advantages over the TL07x, like not suffering from phase reversal with input voltages near the negative supply rail so they are useful and will go back into the parts box.

Show threadJohnS_AZMar 10
@Sandelinos
findchips.com is your friend.
(Digikey is ALWAYS my first pick)
https://www.findchips.com/search/TL072IP
Findchips: TL072IP Price and Stock Results

TL072IP price and availability by authorized and independent electronic component distributors.

Show threadSandelinosMar 10
@JohnS_AZ Personally I get my parts from LCSC these days. The Unisonic Tech TL07x chips I buy from them are half the price of those TI ones you linked and because they stock these smaller asian brands they even have stuff that's not available on Digikey or Mouser at all, like DIP-16 LM13700 clones.
Show threadLarsNygardMar 10
@Sandelinos
I have to check if my lm358's are actually TL072's.... :-p
Show threadRue MohrMar 10
@Sandelinos you got that from the profile or?
Show threadSandelinosMar 10

@RueNahcMohr I did 3 tests with them.

1. Connected the non-inverting input to GND, the inverting input to V+ and the output to GND through a 10k load resistor. Measured voltage difference between output and V-. This is ≈0.7V with a LM358/324 and ≈1.6V with a TL07x because of differences in their output stages.

2. Same as 1 but with the inputs flipped and measuring the output voltage difference to V+. This is ≈1.4V with a LM3xx and ≈1.0V with a TL07x.

1/2

Show threadSandelinosMar 10

@RueNahcMohr

2/2

3. Set the opamp up as a buffer and connect the noninverting input to V-. A TL07x will output a positive voltage because of it's phase reversal quirk, while a LM3xx will output a voltage close to V-.

Show threadvk3kriMar 11

@RueNahcMohr @Sandelinos

This might be a clue: LM324 inverting amp Voltage gain =5.5, freq = 4.6Khz The cro image is about 7V pk-pk.
Don't get me wrong I love the little buggers for low voltage non audio applications, but if you must use them for audio, hang a 5k6 resistor off the output to -ve supply to pull the 'top' output transistor into class A.
I think some of the datasheets mention this trick.

Show threadftgMar 11
@vk3kri @RueNahcMohr @Sandelinos
Didn't this also work for LM358 & Co.?
Show threadvk3kriMar 11

@ftg @RueNahcMohr @Sandelinos
LM324 is just two LM358 in a trenchcoat.

Find out more than you ever wanted to know at https://www.ti.com/lit/an/sloa277b/sloa277b.pdf?ts=1773218858129

Show threadRue MohrMar 11

@vk3kri @ftg @Sandelinos

THIS IS AWESOME YOU JUST SAVED ME A PARTS DRAWER!!!!

"LM324" "LM358"

"LM324/358"