I'm Back- sort of

[Harald Kapp]

You may try Fritzing to lay out the prototype board, whether it be stripboard or perfboard (see here incl. link to download). Fritzing is not the only software, but I think it is a good one - and free.
This helps you arrange the components for a visually agreeable and easy to wire prototype.
Imho a well constructed prototype is half the way to a working product (even if the prototype is the only one you ever build). A well designed prototype makes it easier to follow signals, to swap components etc.

 

[SparkyCal]

Thank you. These are all good suggestions. I have check my connections with a multimeter and all are signalling continuity and none are shorting. But who’s knows for sure?

I am at a crossroads. I may halt this project and take on a simpler one for now, or I may continue to try to figure this one out.

or maybe I rebuild with the ideas here and a quality op amp. Not sure yet.

 

[SparkyCal]

I took a break from the stomp box project and quickly put together this one:

It's a super easy build, and it actually works well. I plugged it into a bass amp, and it really sounds like a kick drum. (bass drum for non musicians - big round drum that sits on the floor and faces outward, for those who don't listen to music ;-).

Anyway, when I get a chance, I'll record it and let you folks hear.

 

[Martaine2005]

kick drum. (bass drum for non musicians

Bass drum = kick drum for NEW musicians).
My kit was like this : But I had high Tom Toms too. 13 piece, double bass drum!

Martin

 

[SparkyCal]

Bass drum = kick drum for NEW musicians).
My kit was like this : But I had high Tom Toms too. 13 piece, double bass drum!

Martin

Those were the days when music was made by real people, playing real instruments. Not loops and pre-made beats that anyone can drag around, regardless of musical sense.

 

[SparkyCal]

Harald, Bertus and Audioguru- I just wanted to let you know that I did follow top with your suggestions about Frtizing etc. I was not able to find an appropriate frizzing program for a few reasons: I am using g an iMac, whisk makes Windows based programs not possible. Some odd the links were broken, and some were pay sites. BUT...I recall that I purchased some electronics software, when I was hear a while back. I have something called EveryCircuit- whihc allows for design, but it may not be as automated as the ones you folks mentioned. I also have EE Toolkit, which is a Coll program that has tons of electronics equations, data sheets and tools.

I just noticed that Everycircuit has a bunch of searchable circuit designs, including guitar stuff.

Anyway...I will probably select anothere guitar based projects, although I don't know which yet. once I decide, I will start a new thread and title it more specifically to the new project.

 

[SparkyCal]

Here is an example of a schematic I found in Everycircuit, but it does not specify which kind of op amp is needed. The only thing it specifies is that its gain is 100 kV/V

I am wondering if any of the op amps I have can be used.

Bertus- the handbook you provide on op amps, I began to read and it has been helpful- but then it got really technical and it lost me. But maybe I will circle back to it and see if it will shed light on how to determine if an op amp can meet the 100kV/V requirement of this circuit

 

[bertus]

Hello,

Did you try this site?
https://en.freedownloadmanager.org/Mac-OS/Fritzing-FREE.html

Bertus

 

[bertus]

Hello,

When you look at the 4558 datasheet, you will see that it has an open loop gain of 100 dB.
Each 20 dB is a factor of 10, so 100 dB is a factor of 100.000.
Have a look at the attached PDF for more info on the decibels.

Bertus

 

[SparkyCal]

I don't know how I missed that site. I just downloaded the software and it seems to have worked. I have not had a chance to use it yet. Thank-you!

 

[Audioguru]

Almost all opamps have a typical voltage gain of 100,000 at DC. But the maximum gain in pedal circuits is only about 1000 times less.

The new distortion pedal you posted is the same circuit as you had before but re-arranged:
1) Dual-polarity power supply. The other one had the opamp biased at half its single positive supply.
2) Inverting circuit with a very low input resistance that cannot be driven from a guitar pickup. The other one has its very high resistance non-inverting input as the input from the guitar pickup.

 

[SparkyCal]

Hmmm. I think I want to stick to single power supply with biasing

 

[SparkyCal]

Hi guys: As you know, I've completed the Cigar Box project. I've also just recently completed this project:

The main reason I did it, is that I had to get some wins under my belt. It gets discouraging if you keep going at the same circuit and can't get it to work. So, I shelved the overdrive circuit for now.

The new simple overdrive I built ( as referenced above) works as designed. The problem however, is that it does not have a very loud signal. I have tried it through a mini Orange guitar amp. I can hear the distorted sound and there is absolutely no buzzing- which is good. I suppose that if I plug it into my Fender Hotrod amp, it will sound louder and better, but I have not tried that yet.

I am guessing that it is because this circuit relies on a transistor, rather than an op amp. thus, the volume is not very loud.

True?

 

[Audioguru]

I simulated the simple overdrive circuit. Its output level is high when it is driven from a low impedance signal source.
Its input impedance is too low to be driven by a guitar pickup. It reduces the pickup output level especially at high frequencies because its input impedance is about 33k ohms when a guitar amplifier has an input impedance of at least 1M ohms (30.3 times higher.)
Maybe that is what the designer and you want?

Here is the simulation with a sinewave input. Its output produces fixed level squarewaves.

 

[SparkyCal]

Thanks Audioguru. I’m not the slightest bit impressed with the circuit this person designed and I certainly would not use it for any serious guitar work. I was more pleased that I built it and it worked. I’d like to find a circuit that only utilizes a biased op amp. No diodes for now. I figure, walk before running.

 

[Audioguru]

I’d like to find a circuit that only utilizes a biased op amp. No diodes for now.

A properly biased opamp produces no distortion until it is turned up to severe clipping.
Diodes produce "soft clipping" at a fairly low level.

 

[SparkyCal]

AudioGuru. This would simply be an excersize to see if I can get sound. Assuming I can conquer that step, I can consider adding diodes. I would like to break down the build do that it reduces errors and makes them easier to problem solve

 

[Audioguru]

Here is the same opamp circuit you had before but without the pots and diodes:

 

[SparkyCal]

Here is the same opamp circuit you had before but without the pots and diodes:

Thank-you. I see resistor values are different on each drawing. Which one are you suggesting? The one where the gain is 201?

 

[SparkyCal]

Also, I only have the three op amps. 4558D. 741CP and the TL082. Which would be best for this circuit? From what I gathered here and elsewhere, the 458D, although older, isn't a terrible choice.