Hi all, can I have some help debugging an Orange Squeezer build, please?
I'm building it on stripboard, from the Tagboard effects site: https://tagboardeffects.blogspot.com/2012/02/orange-squeezer.html
Schematic for reference here: https://images.app.goo.gl/NLzCKioJBhS1tsYz6

There's so sound when the pedal's engaged, and the 4558 op amp IC is getting quite warm. Not too hot to touch and no magic smoke released yet, but "this seems bad" warm.
I'll check for shorts and post up some voltages tomorrow, but I'm wondering whether it could be a bad chip (it was rescued from an old tape recorder), or whether a shorted/bad diode could be responsible?

tsk tsk tsk. THE circuit diagram please, not a page of circuit diagram-alikes. and why oh why would you use a dual opamp when you only need a single, and worse, leave the unused half floating, incorrectly terminated, just asking for oscillating and overheat problems? no, really, why?

also, photos of your build, please. the rules, y'no.

Quote from: duck_arse on January 06, 2024, 09:25:33 AMtsk tsk tsk. THE circuit diagram please, not a page of circuit diagram-alikes. and why oh why would you use a dual opamp when you only need a single, and worse, leave the unused half floating, incorrectly terminated, just asking for oscillating and overheat problems? no, really, why?

also, photos of your build, please. the rules, y'no.

  my bad!
I posted this up just before heading off to bed in a burst of enthusiasm and am effort to quiet the troubleshooting brain by phoning friends.

Here's the schematic including the other half of the op amp, and the jfets and diode marked up.
I'll post voltages and pics of the board/build later on today.
The other half of the op amp isn't floating, I thought about redesigning the stripboard for a single op-amp but it was just easier to go with it as is from the Tagboard effects site, and use up a rescued Jellybean IC

Got it!
Solder bridge between pins 5 and 6. It didn't work immediately, though, I think the IC wasn't properly seated in the socket. After some fiddling it made noise like it's supposed to!
I tried the other IC in the for comparison (the one that was first in the socket when I noticed it was getting hot) and it immediately got very hot, so that one's toast.
The other one is back in, the bias is adjusted to give some spank and sparkle, and I'm calling it good

Thanks DA for the prompt, it got me back to basics. For anyone that's interested I can post voltages later on

Cheers,
Pat

The unused input tied to GND disturbs me slightly.  Wouldn't V_REF be better?  (I.e. the other non-inverting input.)

Quote from: bluebunny on January 07, 2024, 06:36:04 AMThe unused input tied to GND disturbs me slightly.  Wouldn't V_REF be better?  (I.e. the other non-inverting input.)

indeed. this thread is an object lesson in why vero without circuit dia = disaster. for everybody. the other opamp rule is don't exceed the common-mode input voltage range, which we always check on our datasheets, because it is only special parts that will allow/include 0V. what's the range for your part number, Patrick?

Been thru this exercise, got pooped out until I rebuilt using Mark Hammers improved OS. You can see how the "other half" is connected.

I call it a limiter, not a compressor. And once upon a time I collected this diagram. The work was very interesting and high quality. Real, soft limiting.
It will probably work well on new elements too. With shielding of the board in a metal case and other precautions for shielding input circuits.
And with the selection of a good photoresistor range.
(but I don't know how to achieve the same results with a different, convenient power supply scheme).

Quote from: bluebunny on January 07, 2024, 06:36:04 AMThe unused input tied to GND disturbs me slightly.  Wouldn't V_REF be better?  (I.e. the other non-inverting input.)

I can try that, for sure.

Quote from: duck_arse on January 07, 2024, 08:02:35 AM

Quote from: bluebunny on January 07, 2024, 06:36:04 AMThe unused input tied to GND disturbs me slightly.  Wouldn't V_REF be better?  (I.e. the other non-inverting input.)

indeed. this thread is an object lesson in why vero without circuit dia = disaster. for everybody. the other opamp rule is don't exceed the common-mode input voltage range, which we always check on our datasheets, because it is only special parts that will allow/include 0V. what's the range for your part number, Patrick?

The common mode input voltage range on this chip is +/- 14V, and the absolute maximum differential input voltage in +/- 30V so I think it should be alright, although there's a line in the maximum ratings that the output short circuit to ground (one amplifier at a time) is an unlimited time and the first chip is definitely cooked, so maybe it's different IRL.

I haven't heard of it being an issue in all of the OS threads I've read so far, is it that the way the second op-amp is configured shortens its lifespan but not by enough that it's noticeable to most people using the pedal, or that it's genuinely OK? Asking for my own learning.

Quote from: Phend on January 07, 2024, 11:29:58 AMBeen thru this exercise, got pooped out until I rebuilt using Mark Hammers improved OS. You can see how the "other half" is connected.

Nice, thanks! I might try modding mine to use the second op-amp. It didn't sound like I needed a bright switch when I fired it up, but I'm testing it with a guitar that has G&L MFD Z-coil pickups (ceramic magnet split coil humbuckers) so the bright switch might be more useful for alnico PAF-style pickups.

Quote from: sinthmart on January 07, 2024, 02:42:20 PMI call it a limiter, not a compressor. And once upon a time I collected this diagram. The work was very interesting and high quality. Real, soft limiting.
It will probably work well on new elements too. With shielding of the board in a metal case and other precautions for shielding input circuits.
And with the selection of a good photoresistor range.
(but I don't know how to achieve the same results with a different, convenient power supply scheme).

That look like a fun project. You could try breadboarding it and running it at 9V?
I'm not sure what the symbols near the characters "Bxon" are, unless it's input/output switching and I'm not familiar with the symbols

Quote from: patricks on January 07, 2024, 05:00:15 PMI haven't heard of it being an issue in all of the OS threads I've read so far, is it that the way the second op-amp is configured shortens its lifespan but not by enough that it's noticeable to most people using the pedal, or that it's genuinely OK? Asking for my own learning.

https://www.ti.com/lit/ab/sboa204a/sboa204a.pdf?ts=1704651307825

https://www.analog.com/en/technical-articles/avoiding-noise-and-power-problems-with-unused-op-amps.html

https://circuitdigest.com/article/how-to-properly-terminate-an-unused-op-amp-to-avoid-noise-and-poewr-related-issues

https://www.electronicproducts.com/properly-terminating-an-unused-op-amp/

Quote from: bluebunny on January 07, 2024, 06:36:04 AMThe unused input tied to GND disturbs me slightly.  Wouldn't V_REF be better?  (I.e. the other non-inverting input.)

You get my vote. Tying the input to a level that the op-amp probably can't drive the output to reliably doesn't strike me as a great idea either. There are chips that you could use where you'd probably get away with it, but mostly you won't. Unhappy op-amps make for uphappy circuits! 

Quote from: patricks on January 07, 2024, 05:00:15 PMwhat the symbols near the characters "Bxon" are

Probably case connectors. (Russian guitarists did not use 1/4" plugs a lot.)
X1 X2 could be internal connnectors.
S1.1 S1.2 would be the stomp switch.

Quote from: antonis on January 07, 2024, 05:17:04 PM

Quote from: patricks on January 07, 2024, 05:00:15 PMI haven't heard of it being an issue in all of the OS threads I've read so far, is it that the way the second op-amp is configured shortens its lifespan but not by enough that it's noticeable to most people using the pedal, or that it's genuinely OK? Asking for my own learning.

https://www.ti.com/lit/ab/sboa204a/sboa204a.pdf?ts=1704651307825

https://www.analog.com/en/technical-articles/avoiding-noise-and-power-problems-with-unused-op-amps.html

https://circuitdigest.com/article/how-to-properly-terminate-an-unused-op-amp-to-avoid-noise-and-poewr-related-issues

https://www.electronicproducts.com/properly-terminating-an-unused-op-amp/

Oh cool! Thank you for the links - I'm guilty in this circuit of committing one of the sins that's a pet peeve of mine in the sciences, quoting/citing something incorrectly accepting it as the truth.
I didn't realise there were so many ways to do it.

I think I'll build out my board with Mark's mods and use the other half of the chip to its best ability. Sort of as an homage to the pedal I cooked in the process

Quote from: PRR on January 07, 2024, 06:47:52 PM

Quote from: patricks on January 07, 2024, 05:00:15 PMwhat the symbols near the characters "Bxon" are

Probably case connectors. (Russian guitarists did not use 1/4" plugs a lot.)
X1 X2 could be internal connnectors.
S1.1 S1.2 would be the stomp switch.

Ah, brilliant, thanks!

Quote from: sinthmart on January 07, 2024, 02:42:20 PMI call it a limiter, not a compressor. And once upon a time I collected this diagram. The work was very interesting and high quality. Real, soft limiting.
It will probably work well on new elements too. With shielding of the board in a metal case and other precautions for shielding input circuits.
And with the selection of a good photoresistor range.
(but I don't know how to achieve the same results with a different, convenient power supply scheme).

Those Russian magazine circuits are always interesting.

To look at it doesn't seem like a clean circuit:   
- Two gain stages outside of the ALC loop which have quite a bit of gain.   
- Also taking the output from across V1 isn't going be clean.   Maybe need a resistor across V1, then a separate cap from the opamp to R15 (75k).

This is an old scheme and of course, perhaps not perfect. But perhaps there is a healthy, useful "grain" in it, a thought)).
And I decided that someone would be curious.
And I repeat, perhaps the quality of the photoresistor is of serious importance in this case. It (the photoresistor) in the circuit is stated to be one of the best at that time.
----------------------
It's funny that it turns out that this scheme is not available on the Internet at all!! ))) Whereas I still have this original paper page, and I forgot which magazine it was taken from.
(year approximately 1978-1985)
I thought everything was on the Internet))

Quote from: patricks on January 07, 2024, 05:00:15 PM

Quote from: duck_arse on January 07, 2024, 08:02:35 AMthe other opamp rule is don't exceed the common-mode input voltage range, which we always check on our datasheets, because it is only special parts that will allow/include 0V. what's the range for your part number, Patrick?

The common mode input voltage range on this chip is +/- 14V, and the absolute maximum differential input voltage in +/- 30V so I think it should be alright, although there's a line in the maximum ratings that the output short circuit to ground (one amplifier at a time) is an unlimited time and the first chip is definitely cooked, so maybe it's different IRL.

I haven't heard of it being an issue in all of the OS threads I've read so far, is it that the way the second op-amp is configured shortens its lifespan but not by enough that it's noticeable to most people using the pedal, or that it's genuinely OK? Asking for my own learning.

nearly. you missed the important part - supply voltage +/-15V. that says when you have +/-15V, don't take the inputs closer than 1 volt of either supply. they often put

V_cc+ -2V, V_cc- +2V. or similar. and so with 0V and +9V supply, 0V and +9V are outside the range the engineers allow for correct datasheet operating behaviour. and we always like to stick to what the engineers tell us is the correct, hereabouts anyway. (except that 0/9V is quite often less than quoted minimum allowable supply.)

Thanks duck!

Quote from: Phend on January 07, 2024, 11:29:58 AMBeen thru this exercise, got pooped out until I rebuilt using Mark Hammers improved OS. You can see how the "other half" is connected.

Resurrecting the thread to ask whether this "spare" op amp stage could be configured as an input buffer to split the signal, and the gain stage in the stock schematic serve as a mixer to add a clean blend rather than an additional gain stage?

I rebuilt it tonight, reconfiguring the starboard/vero layout for a single op-amp, and it worked a treat. I auditioned an LF351 and an NE5534 (I wish those were labelled the same way as the TL series chips, that'd make a lot more sense) and preferred the LF351 (I could hear some distortion with the NE5534. Call me a nerd, but I really like the LF351/353 chips).

If anyone's interested I can post up a layout for adapting the tagboardeffects stripboard/vero layout to use a single op-amp (redesigning the layout for a single op-amp would be useful too, but I'll see whether I've got time to make one up).

Second quick update, I added Mark's treble boost mod (47k resistor in series with a 2.2nF capacitor, soldered across the 82k resistor). The change is subtle but adds some welcome brightness that I was looking for. Link is here: https://www.diystompboxes.com/smfforum/index.php?msg=537631