Smart People Factory - Red Threat [traced]

[Matlevo12]

Hi,

I spent a few days with this pedal and took the opportunity to trace it. Didn't triple check but this time I didn't do it at 2 in the morning so it should be alright !
I don't know if it's a clone or modded clone of something existing, but it'll sure remove the wallpaper of your house in a minute if you want it.
It's LOUD, has TONS OF GAIN, and of course, is very noisy !

[Manfred]

I am intending to make a PCB clone, so my question.
What are the dimensions of the PCB?

[Matlevo12]

I am intending to make a PCB clone, so my question.
What are the dimensions of the PCB?

The enclosure is a 1590bb, I don't have the pedal with me anymore. It could be improved I think, there were 2 bridges for the ground traces, and the components far away from each other. I don't know about breadboard, but on a proper pcb I think it could fit on a 125B with mounted pots.

[Manfred]

The enclosure is a 1590bb, I don't have the pedal with me anymore. It could be improved I think, there were 2 bridges for the ground traces, and the components far away from each other. I don't know about breadboard, but on a proper pcb I think it could fit on a 125B with mounted pots
Thanks!

That's a pity, but no problem, I can scale the PCB another way.

[Matlevo12]

I might try and make one with easyeda one of these day, if you're interested.

Does anyone has an idea where the circuit might come from ?

[ppluis0]

The first and second op-amp stages are referred to ground instead to be biased at 4.5V ???

[Matlevo12]

The first and second op-amp stages are referred to ground instead to be biased at 4.5V ???

Yep.

[Manfred]

Here is the preview of the PCB Clone layout, now I will insert the identifiers and values of the components.
The dimensions of the PCB are 3.4 x 2.2 inches.

[Manfred]

I made this PCB clone according to the photos.
Thanks to Matlevo12 for tracing and drawing the schematic.
There are differences between the values printed on the PCB.
C1 and C3 have the value 1nf in the schematic and 10nF on the PCB, C6 and C10 have the value 47pF in the schematic and 470pF on the PCB.
The identifier C16 appears twice on the PCB, for the 100uF electrolyte and for the 20n foil.
I renamed the 20n folie to C17.
I redrew the schematic adding the missing components.

Ready-to-Print PDF-files:

Smart People Factory Red Threat PCB Component Side.pdf

(30.39 KiB) Downloaded 71 times

Smart People FactoryRed Threat PCB Solder Side.pdf

(5.61 KiB) Downloaded 87 times

Sprint-Layout6.0 file:

Smart People FactoryRed Threat PCB Layout.zip

(33.72 KiB) Downloaded 62 times

[Lithium_Grim]

I made this PCB clone according to the photos.
Thanks to Matlevo12 for tracing and drawing the schematic.
There are differences between the values printed on the PCB.
C1 and C3 have the value 1nf in the schematic and 10nF on the PCB, C6 and C10 have the value 47pF in the schematic and 470pF on the PCB.
The identifier C16 appears twice on the PCB, for the 100uF electrolyte and for the 20n foil.
I renamed the 20n folie to C17.
I redrew the schematic adding the missing components.

Why did you leave out the negativ feedback on the second stage?

[Manfred]

Thanks for your hint.
Sorry, I just forgot about the NFB connection.
I have fixed the error in the schematic.

[Lithium_Grim]

I only give negativ feedback

[Manfred]

I only give negativ feedback

According to your motto:

I only give negative feedback and y'all love it!

Yes, I love it too.

[ppluis0]

I'm still intrigued about the fact that IC1a and IC1b doesn't have reference to 4.5 Vcc

How this two stages can work properly ?

[Manfred]

I'm still intrigued about the fact that IC1a and IC1b doesn't have reference to 4.5 Vcc

How this two stages can work properly ?

I drew the schematic according to the PCB, there are indeed no biasing resistors to half the supply voltage.
I ran a circuit simulation with a sinusoidal input voltage at 1kHz.
The circuit works, but, only up to an input sine voltage of 4.2Vpeak-to-peak, after that the sine signal at the output of OP-Amp 1 starts to deform.
I have inserted the biasing, the output signal remains undistorted up to an input sine voltage of 28.8 Vpeak-to-peak.
I think the missing of the biasing is a design error, this was probably not noticed since the output signal of the guitar never reaches 4.2 Vpeak-to-peak.

[Manfred]

Edit!
I edited the last schematic above, capacitor C9 for half voltage was missing.

[Manfred]

I ran another simulation of the first two op-amp stages, putting only the base of R3 (68k) to +V1/2 insteed to ground.
The circuit now works properly.
A further bias resistor to the +input pin 5 of is not necessary, since this is now connected via R1 and R5 to the output pin 1 at about 4.5 volts DC,
and thereby to pin 7 as well.
At pin 1 and pin 7 were before the modifikation of the reference point a DC voltage of about 0V to measure.
I modified the layout and moved R3 so that the lower lead is now at +V1/2.
R1 appears two times on the original PCB, I renamed the Jumper to R11.

Ready-to-Print PDF-files:

Smart People Factory Red Threat V2 Component Side.pdf

(30.33 KiB) Downloaded 59 times

Smart People Factory Red Threat V2 Solder Side.pdf

(5.64 KiB) Downloaded 74 times

SprintLayout6.0-file:

Smart People FactoryRed Threat PCB Layout V2.zip

(33.77 KiB) Downloaded 50 times

[Manfred]

Thanks Jose for taking a closer look at the circuit and finding the circuit fault.

[ppluis0]

Thanks Jose for taking a closer look at the circuit and finding the circuit fault.

Hi Manfred,

I always knew that circuits with single polarity powered op amps had to be referenced to an intermediate voltage.

That's why the diagram for this pedal had me confused.

I take this opportunity to congratulate you once again for your excellent work drawing printed circuits

Cheers,
Jose

[Matlevo12]

Hi.
Sorry i lost track... was there something wrong with what I traced?