I'm Back- sort of

[Audioguru]

Electrosonic and another electronic parts supplier were near Sayal in Scarborough for years but now they are gone.
Amazon and their sellers know nothing about electronic parts so they buy the cheapest from "over there" which are fakes or defective junk.
Digikey and Newark are real online electronic parts suppliers and if you order before 8:00PM then you receive the shipment the next morning.

 

[Harald Kapp]

Wrong thread??

moved to this thread.

 

[SparkyCal]

Okay...since now I have the op amp hooked up correctly, I am turning my mind back to pots.

But before I venture there, I am wondering about the following:

What if I did not hook up any pots (for the moment), and go directly out of the 270R resistor, to the output jack ? Assuming this is possible, that would at least allow me to verify whether the circuit is outputting sound. Then, I will know for sure, it is my pot hookups that are causing the problem, or the circuit itself.

 

[bertus]

Hello,

If you are thinking that the pots on the output are causing trouble, remove them and test if there is some signal coming out of the opamp:

If nothing is coming out, there must be a fault in the setup.

Bertus

 

[SparkyCal]

Good idea. I'll do so and report back once I get a chance.

 

[SparkyCal]

I am getting 4.49v at pin 6, so I think it is working.

Maybe I can try installing one po at a time and get it to work, before installing the next one. Maybe start with the 100K volume pot

 

[Josie]

Hello, yes, it's worth starting with the 100K volume control, it should work

Josee

employee time tracking

 

[bertus]

Hello,

Do you get any audio on the test output?
Only measuring DC does not say everything.
If you want to hook-up the volume pot, do it like this:

Bertus

 

[Harald Kapp]

Well shown, Bertus.
But the capacitor at the output is not required. It is already present as C3 at the output of the opamp. Although it will not hurt having another capacitor there.

 

[SparkyCal]

Thanks guys. Bertus- I have not done that yet, but I will.

Before I moved on to the pots, I was checking other parts of the circuit. The Op Amp pins still have the proper readings- so that's good. And Pin 6 ( the output, has the proper reading).

But I took the readings after the C3 capacitor and after the 270R resistor. After the capacitor, it was below 1 volt and falling, and after the 270R, the reading was almost non existent. If that's the case, how could it possibly do anything?

 

[Audioguru]

C3 passes AC audio but blocks the DC on the opamp output from frying the volume control that should never have any DC on it.
It is normal for C3 to take a few seconds to charge then produce 0VDC at its output. The sudden DC when the circuit is powered produces a POP in the audio.

 

[SparkyCal]

Okay...I will move on then to do what Bertus suggested ad I will report back. Thanks.,

 

[SparkyCal]

Hi- I hooked up the volume pot according to the pic Bertus provided. Unfortunately, I am getting no sound whatsoever to the amp(meaning, to my guitar amplifier) . Although, as I said, the pin readings o n the op amp remain correct.

 

[SparkyCal]

I kow this won't tell you much, but this is what my circuit looks like from top side.

You will notice that I use a set of pin terminals to extend pins 2 and 6. This is so that I have more space to wire up the diodes etc. So, the pin terminals act as extensions of pins 2 and 6.

 

[SparkyCal]

Flip side

 

[SparkyCal]

Guys- in looking at my circuit, I may have figured out an error. I don't have time to write it up or fix it now, but I will report back when I do. I noticed that I inverted my understanding of the 2 and 6 pins extension, which probably lead me to wire the volume pots wrong. Need to look at this later.

 

[SparkyCal]

Sorry to confuse everyone, including myself, but I have concluded that the error referenced above, did not affect anything. You will notice on the pic of the flip side of the circuit board, that I labelled. 2 and 6 in marker (starting at top left) . Actually, the label should have been 6 and 2, But when I looked at the actual connections, I wired them correctly. The label was simply inverted by accident, after the wiring occurred.

So, back to the original problem. I have wired in the volume pot, but I get no sound whatsoever to the guitar amp.

 

[SparkyCal]

Corrected version of flip side

 

[Audioguru]

What a mess of wires all over the place!
Why don't you use perforated stripboard instead? Sayal sell a good one. The parallel strips of copper tracks and a few short straight jumper wires form half of a pcb and the parts for the remainder. It is easy to see what connects to what. the parts can be close together.
The strips are cut to length with a hand tool or gently with a drill bit. Each strip can be used over and over when cut to length.

I have made hundreds of "prototypes" at work where only one custom-made circuit was ordered and usually the stripboard circuit was sold as the finished product. When thousands of a circuit was oredered my stripboard circuit was sent to a pcb manufacturer and assembly manufacturer wIrh a stripboard complex test unit. All circuits made were were built and tested.

 

[SparkyCal]

I have tried stripboard but the quality was terrible. I will have to try buying some from digikeys or somewhere like that