JHS Pulp-n-Peel  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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alexworkman
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Post by alexworkman »

I had a friend ask me to post some guts shots of the JHS Pulp-n-Peel. Here they are. Hope it helps!
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roseblood11
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Post by roseblood11 »

Thanx for sharing!

To retrace it, pictures of both sides of the pcb are needed, and it would be great if you could post all the parts values and mark the pot connections on the pcb.

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Dirk_Hendrik
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Post by Dirk_Hendrik »

Thanks for the photo's
suggestion for JHS:
http://www.ipc.org/ContentPage.aspx?pageid=J-STD-001
Sorry. Plain out of planes.

http://www.dirk-hendrik.com

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Ice-9
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Post by Ice-9 »

That is a horrible soldering job on the wiring.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?

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giubacon
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Post by giubacon »

Dear all,

This post is tagged as traced but i cannot found any schematic.
So, since Pulp n' Peel is just an Orange Squeezer with some cool mods, i just modified O.S like Josh did.
The main mods are the blend control and the Comp control.
See bellow:
pulp.jpg
I tested this circuit and it works so good!
If you have some doubt, feel free to ask me!

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Lithium_Grim
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Post by Lithium_Grim »

Did Josh really just leave the second opamp in the TL072 totally opened??? Not 7 connecting to 6 and 5 to 1/2 V?
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Intripped
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Post by Intripped »

Lithium_Grim wrote: 07 Nov 2021, 12:39 Did Josh really just leave the second opamp in the TL072 totally opened??? Not 7 connecting to 6 and 5 to 1/2 V?
How do you say that?
I mean, are you sure about it?

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Post by Lithium_Grim »

Intripped wrote: 07 Nov 2021, 15:26 How do you say that?
I mean, are you sure about it?
I am reffering to the schematic. It says TL072, but only shows 1 op-amp in use. It has 2 op-amps and the second one should be properly "stubbed" to prevent possible noise. See the TI technotes which has a reference design for that. They advise to connect the output (pin 7) to the inverting input (pin 6) and the non inverting input (pin 5) to 1/2 Vin (not ground!)
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giubacon
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Post by giubacon »

Hi dear all,

Once I did not used the second op amp, I think I can leave it disconnect.
I don’t use the ref voltage (4,5v) in any part of this circuit.
But you can do that in order to reduce possible noise… I don’t have this issue leaving it disconnected.
The mods I refer that Josh did is about blend control and comp control.

Cheers

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Intripped
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Post by Intripped »

Lithium_Grim wrote: 08 Nov 2021, 07:01
Intripped wrote: 07 Nov 2021, 15:26 How do you say that?
I mean, are you sure about it?
I am reffering to the schematic. It says TL072, but only shows 1 op-amp in use. It has 2 op-amps and the second one should be properly "stubbed" to prevent possible noise. See the TI technotes which has a reference design for that. They advise to connect the output (pin 7) to the inverting input (pin 6) and the non inverting input (pin 5) to 1/2 Vin (not ground!)
...ok, now i get your point.
yes, unused opamp pins should be properly terminated, i agree with you!
giubacon wrote: 08 Nov 2021, 13:07 Hi dear all,

Once I did not used the second op amp, I think I can leave it disconnect.
I don’t use the ref voltage (4,5v) in any part of this circuit.
But you can do that in order to reduce possible noise… I don’t have this issue leaving it disconnected.
you had better follow LG's advice

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Post by Lithium_Grim »

Option 2: Use a TL071, just need to rewire the output that is pin 1 in the schematic to pin 6 (output on TL071/ single op-amp) and pin 8 Vcc on the TL072 to pin 7 Vcc on the TL071
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Post by cspar »

Looking at the board the Pulp N Peel might have the other side of the op amp snubbed with the two 10K resistors (R9 and R10) as the voltage divider.

But there is also the extra transistor, 6? 10K resistors (if R7 is 10K) and the fact that it has a buffered bypass.

So it also might be that the always on buffer is the transistor with the other side of the op amp being used for summoning and buffering the mixed signals.

Either way would be functional.

We need to see the other side of the board to really know.
"Just because the forgoing circuits have produced results there is no reason experimenting won't lead to added results." L. E. Darling, in his article containing the earliest published vacuum tube synthesizer circuit, Popular Science Jan 1920

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giubacon
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Post by giubacon »

Dear all,

Last week i studied more this circuit... with this gutshot...
Pulp top.jpg
In conclusion, this version is basically an Buffer n' blend + Standard Orange Squeezer + Little black Buffer (switch)
I traced below the schematic:
pulp.jpg
My plan is to build this schematic on next week, tracing it in Eagle cad.
I will update after test it.

Cheers

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Reachahighernoon
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Post by Reachahighernoon »

giubacon wrote: 13 Nov 2021, 23:30 Dear all,

Last week i studied more this circuit... with this gutshot...
Pulp top.jpg

In conclusion, this version is basically an Buffer n' blend + Standard Orange Squeezer + Little black Buffer (switch)
I traced below the schematic:

pulp.jpg

My plan is to build this schematic on next week, tracing it in Eagle cad.
I will update after test it.

Cheers
That "Comp" control looks oddly a lot like the attack control on the orange smoothie

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Post by twotees »

giubacon, Did you ever get that Pulp n Peel facsimile schematic onto an assembled tested working circuit. I have been holding my breath waiting , since 2021, you said you'd be back in a week?

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giubacon
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Post by giubacon »

Hello , sorry for my long delay … I tested the circuit and it works ! I just forgot to return here and report the status.

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