I'm Back- sort of

[SparkyCal]

I have a ton of the 4558D's, but I was under the impression they were too dated.

 

[bertus]

Hello,

The 4558 are two slightly improved 741´s in one package.
The LF353 is more modern.

Bertus

 

[Audioguru]

An RC4558 or your Japanese version is a dual opamp with a few slightly better specs than a 741 opamp.
One that has maximum input bias current will cause the output to be 4.0V instead of 4.5V.

 

[SparkyCal]

I guess I am better off using the 4558 then? At this point, I just want to succeed in bringing the circuit to fruition. I will probably troubleshoot the existing circuit further. if that goes nowhere, I may build a new one using the 4558.

 

[bertus]

Hello,

Watch the pinouts of the chips:

The 741 is single, the 4558 is dual.

Bertus

 

[SparkyCal]

Thanks Bertus.!!!

It seems like that memory is faulty. I did not buy the 741's at a local store- I thought I did, but I'm wrong. Here are links to what I bought (long ago- when I was first coming here).

https://www.amazon.ca/gp/product/B07LFSV98Q/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

https://www.amazon.ca/gp/product/B06XK6VW8X/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I also have these on order:

https://www.amazon.ca/gp/product/B07C3HSDGC/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

 

[SparkyCal]

Hey guys- maybe due to the fact that I have a PCB board holder that rotates the board, I had wired some pins incorrectly. So, I cut the wires to every pin and rewired. After doing that, here are my readings:

Pin 2. 7.68

Pin 3 4.09

Pin 6. 9.0

Pin 7 8.20


This is with the 741 op amp. I sense these measurements are still wrong. I am tempted to do a rebuild with the 4558Ds.

Or, does anyone have any views on which of the following Op Amps, that I have, or that I will shortly receive, I should use on a rebuild.

https://www.amazon.ca/gp/product/B07LFSV98Q/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

https://www.amazon.ca/gp/product/B06XK6VW8X/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I also have these on order:

https://www.amazon.ca/gp/product/B07C3HSDGC/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1



Bertus- do you think thre 4558D is the best of this lot? AudioGuru? Harald? Opinions appreciated.

 

[Audioguru]

Now you swapped the output pin6 with the +power supply pin7.
Even if the opamp did not release its magic smoke, it is probably ruined.

 

[SparkyCal]

I am not near the circuit now, but pin 7 has always been routed to the positive rail, I believe.

 

[Audioguru]

Wrong thread??

 

[Harald Kapp]

I guess I am better off using the 4558 then?

I doubt it. Why don't you buy a few TL081 as per the original design? You are struggling enough with other issues like pinouts etc. Spare yourself from unnecessary issues that may arise from using the wrong components and not knowing how to change the circuit to accommodate these.

 

[SparkyCal]

Hi Harald:

That's probably a good idea.

Here is a link to my local electronics store (It's about a 20 min drive- which is not bad). Here is the one they have:

https://secure.sayal.com/STORE2/View_SHOP.php?SKU=192017


Maybe I will also see if they have other more modern ones, for future projects. I'll look at the ones mentioned in the papers Bertus posted. There were a few mentioned that apparently work well with biased circuits.

 

[SparkyCal]

As I think about this, I kn ow that the power section of the circuit works as intended. I think the diode portion will work as well. So, probably the best thing to do is get the right op amp and then pop it into the socket and rewire the socket to make sure the wiring is correct. I don't thin k a complete rebuild is necessary.

Plus, my intention is to get this one working, so that I can rebuild it and place it into a professional stomp box cover. I have three steel stomp box casings with the stomp box switches, which I had from way back when I was first here; that I did not end up using. So, I thought, let me get this circuit working and then rebuild it with a view toward a finished version. All the more reason why buying the right op amp makes sense as well.

Thanks for hanging in guys. I'll report in once I am at the next stage.

 

[SparkyCal]

AudioGuru- is there a particular op amp that you're found of? I figure, if I go in to pick up some parts, I may as well pick up a few extra ops amps that are more modern.

 

[SparkyCal]

I also found this on Amazon- made by Texas Instruments, so it's American made. https://www.amazon.ca/Texas-Instrum...exas+instruments+op+amp&qid=1621441228&sr=8-2

 

[bertus]

Hello,

The following book will show you more modern opamps and their use:
https://archive.org/details/fe_Op_Amp_Applications_Handbook_Newnes_Walt_Jung

Bertus

 

[SparkyCal]

Thanks so much Bertus. The trick will be to see if the local electronics store carries them. But I will check it out.

 

[SparkyCal]

Fingers crossed, Maybe, we've solved this. I popped in a new 741 op amp into the socket (in case I fried the other one). I adjusted all the wiring to the socket. Here are my new readings:

Pin 2. 4.47

Pin 3 4.06

Pin 6. 4.47

Pin 7 9.01

 

[Audioguru]

I have bought a few things at Sayal. They are an electronics liquidator from India. I bought some Sylvania clock radios tor $1.75 each.
I souped up low frequencies of one with larger capacitors and connected a 2-way speaker (6.5" woofer in a ported enclosure and a dome tweeter) making it hifi.
I bought some Philips modern 5V/2A power supplies for $1.50 each.
National Semi genuine LM3915 ICs cost less than anywhere else.
They have a good selection of Hammond little plastic enclosures.
Their stripboard is high quality.

BUT their no-name-brand LEDs are very poor quality and a Weller soldering iron tip was probably a fake.

The voltages on your new 741 opamp are fine and it will work almost the same in that distortion-producing circuit as a TL081.

 

[SparkyCal]

Thanks Audioguru. I'm glad the readings are fine now.

I didn't know that about Sayal. There are not many electronic component vendors around (at least, not like before). Sayal is the closest to me and with Covid and all, it's either Sayal or Amazon ;-(.