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A Stretch

Martaine2005

May 12, 2015
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I thought you had tried different op-amps from your assortment?.
Obviously changing the pin arrangement.
Did you try testing them?.
I don’t think you are reading all replies.
If the circuit worked for a bit on breadboard, it must be connections.
Try not to be sensitive, push the connections in!. Terminate them... Plug it in and and check while wiggling connections. Breadboards are good but also known for bad connections. Be a brute and push, wiggle while checking.

Martin
 

SparkyCal

Mar 11, 2020
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Martin. I don’t have an assortment yet. I have a ton of the 4588d and a few Tl (Forgot the rest) not home at the moment. If The one I am using is old and out dated, I thought it may make sense to use the 4558d which I assume is somewhat better?

I asked for advice on assortments but am having second thoughts given it would be from amazon
 
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Martaine2005

May 12, 2015
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I said in my post, somewhere. Keep on with what you have. Old doesn’t mean it wont work.
Hell, my ex wife does.
Keep on pluggin’ you’ll get there.

Martin
 

Audioguru

Sep 24, 2016
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I wonder what would happen if i drop a 4558D in the same circuit but make sure the pins are re-mapped. Might that be better?
The 4558 is also old and is an "improved" dual 741 opamp. Its high frequency bandwidth goes up to 40kHz (the 741 goes up to 9kHz) and it produces fairly low noise (the 741 is so noisy that the datasheet does not say how much). The 4558 has a recommended 10V minimum supply voltage. Your 9V battery will drop to 6V during its life.
 

SparkyCal

Mar 11, 2020
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The Gain calls for a 50K pot. i only have 100K pots. Do you think that's ok?
 

bertus

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Nov 8, 2019
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Hello,

With the 100K potmeter the gain range will be bigger.
You can set lower gain with the 100K potmeter.
With the 50 K potmeter the gain range will be about 20 to 200 times.
With the 100 K potmeter the gain range will be about 10 to 200 times.

Sparcal DOD_OD_250_schem.png

Bertus
 

SparkyCal

Mar 11, 2020
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Thanks Bertus. Glad to hear i can use it.

I am stuck. C4 is a 4.7 uF capacitor. I don't have a film capacitor in that size. I do have a 4.7 uF electrolytic capacitor. From the picture on this page https://www.diystompboxes.com/projects/offboard.html. it looks like C4 is a cannister type capacitor, whihcb looks like an electrolytiuc. But I can't be sure. And he says nothing about polarity. so i wonder if I can use my 4.7 uF electrolytic capacitor for C4?
 

Martaine2005

May 12, 2015
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The picture shows three electrolytics.
Two smaller grey and one larger black. The negatives are the stripe side.

Martin
 

bertus

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Hello,

I have putten large + signs at the electrolitic capacitors:

Sparcal DOD_OD_250_schem_anno.png

Bertus
 

Audioguru

Sep 24, 2016
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The circuit designer does not know how to calculate the value of a coupling capacitor or he made a typo. The 4.7uF capacitor C4 passes earthquake frequencies down to 3.4Hz through the 10k resistor R6 into the diodes. A 330nF film capacitor (marked 334) will pass music frequencies down to 48Hz. The lowest frequency on an ordinary guitar is 82.4Hz.

With the over-value capacitor, the guitar might make a wanted "Thump" sound when it is stomped on. Aren't you supposed to stomp on the "pedal" and not on the guitar?

I increased the size if the schematic and photo to show the polarity of C4:
 

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SparkyCal

Mar 11, 2020
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Hi guys. Thanks so much for your ongoing interest and support. Bertus, Martin, AudioGuru- you guys have been great, as well as all the others.

I am pleased to say that i have achieved success in phase 1. What i mean is that I have connected the op amp and the volume and gain, and i actually have distortion! I will hook up the diodes next, and hopefully, pull this off.

Here is what made the difference:

1, Coaching from you folks
2. I went back to breadboarding
3. I cut the legs of my components short, so that they were not dangling everywhere on the breadboard.
4. I actually took the time to make good pots, wired them up with solder, and used those heat activated sleeves to protect the soldered connections. I used color coded wire and also soldered the ends right up to breadboard pins.
5. I printed each page of the tutorial, put it in order in a binder, and religiously followed each step.

In other words, rsather than get over excited and consequently , sloppy, i took my time and did it very neatly!
 

Audioguru

Sep 24, 2016
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Horray! I am glad to see that you got it to sound as awful as you want.
Oh, without the diodes that cause the distortion? Then i guess you have the opamp clipping its head off.
 

SparkyCal

Mar 11, 2020
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AudioGuru- the tutorial suggests that I test it without connecting. the diodes just yet. So i did that just to make sure I was doing it right. For me, it won't be about the actual distortion this time around. It's just about learning the concepts. I am not doing the diodes thing tonight. I think i need a break from this for tonigjht ;-)

If ever I get this whole thing done, I'm going to call this pedal 'Insomnia" cause God knows I've lost a lot of sleep over it. lol

The circuit designer does not know how to calculate the value of a coupling capacitor or he made a typo. The 4.7uF capacitor C4 passes earthquake frequencies down to 3.4Hz through the 10k resistor R6 into the diodes. A 330nF film capacitor (marked 334) will pass music frequencies down to 48Hz. The lowest frequency on an ordinary guitar is 82.4Hz.

With the over-value capacitor, the guitar might make a wanted "Thump" sound when it is stomped on. Aren't you supposed to stomp on the "pedal" and not on the guitar?

I increased the size if the schematic and photo to show the polarity of C4:
Audioguru- sorry but I did not see your post till now. I will have a look tomorrow when my brain is fresh. I did note that if i turn the pots up, it can start humming 9not in a good way_ pretty quick. so I have to be gentle.
 
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SparkyCal

Mar 11, 2020
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Hi guys. I took a strategic break and built the attached contraption. I made it out of a bamboo utensil drawer I found at the dollar store.

Basically, it will make using pots, inputs and outputs and breadboards easier to work with. It will also make the entire project portable so that i can pick it up and move it when I am not working with it.

I also thought it would help here, because hopefully I can eliminate errors that are due to haphazard breadboard connections and the like.

I plan to re-breadboard this circuit using this contraption, once I get a chance to. I'll report in.
 

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SparkyCal

Mar 11, 2020
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I rebuilt this circuit on the new breadboard comngraption, and it worked instantly. I have not yet installed the diodes. I'll do that next and report in,.

Having a nice tidy breadboard environment to work with, with soldered connections for pots etc. , has made a real difference. i wish i'd have done that sooner.
 

SparkyCal

Mar 11, 2020
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Well, it was a stretch for me, but with your help, we did it! The breadboard build, including the addition of diodes, worked!!!! I have included a link to what it sounds like below. I can hear AudioGuru say that it's noisy and the distortion sounds awful, and he'd be right, but, for me, it was the process of learning- which I have learned a lot.

Thanks to all of you, Bertus, AudioGuru, Martin and everyone else. Could not have done it wihtout you.

Have a listen =.

https://drive.google.com/file/d/1XEuAndT_fR1jCv_HbQm1VlR7pNWhn6Op/view?usp=sharing

(not my best guitar playing by no means)

My next step is to PCB this but since I know it works, I will not trouble you with this particular project any further. Any mistakes I may make doing the PCB board, will be sloppy ones that i can fix myself- as now, I know the design works.

 

Audioguru

Sep 24, 2016
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I can play millions of MP3 songs but not your guitar in the "cloud".
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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Sounds reel gud, @SparkyCal! Glad to hear you finally got it all together!
On a side note... are you aware of any FX box (stomp or otherwise) that will make an electric guitar sound like an acoustic banjo?
 
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