Ramble FX - Marvel Drive 1.0  [traced]

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Re: Ramble FX - Marvel Drive 1.0

Postby POTL » 23 Feb 2018, 23:45

Hello everyone, I am confused by the power switching scheme, or am I mistaken, or does the voltage change only in the second half of the VB circuit, explain how in fact the voltage changes, on the whole circuit or only the second part of it?
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Re: Ramble FX - Marvel Drive 1.0

Postby Nocentelli » 24 Feb 2018, 11:23

VA and VB are both switched between 9v and 18v - They are connected at the node that links to the two 47ohm resistors that feed these points,so both VA and VB will either provide 9v direct from the supply, or 18v from the charge pump. The only difference between VA/VB is that they have separate power filter caps and resistors.
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Re: Ramble FX - Marvel Drive 1.0

Postby POTL » 24 Feb 2018, 14:20

Nocentelli wrote:VA and VB are both switched between 9v and 18v - They are connected at the node that links to the two 47ohm resistors that feed these points,so both VA and VB will either provide 9v direct from the supply, or 18v from the charge pump. The only difference between VA/VB is that they have separate power filter caps and resistors.

Thanks. :thumbsup
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Re: Ramble FX - Marvel Drive 1.0

Postby mr coffee » 27 Feb 2018, 02:10

OK,
Here's the (I hope) last post in this thread, so folks can find the correct schematic without going through all kinds of confusion getting the correct schematic.

I made it a bit easier to read and cleaner, the last schematic was already correct.

mr coffee
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Manfred (29 May 2018, 06:26)
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Re: Ramble FX - Marvel Drive 1.0

Postby JabboWookie » 29 May 2018, 01:54

Long time listener, first time caller...

I built this off of Bugg's PedalPCB Marble Drive, which I'm assuming is based off of this schematic. I'm getting a whine from the TC1044S when I'm in 9V mode. Everything's good in the 18V mode. I've tried two different chips with the same result. Any ideas why this might be happening? Obviously it goes away when I pull the chip.

https://www.pedalpcb.com/product/marbledrive/

Any help would be appreciated, thanks!
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Re: Ramble FX - Marvel Drive 1.0

Postby Manfred » 29 May 2018, 06:50

I'm getting a whine from the TC1044S when I'm in 9V mode.


I think that the whine is not caused by the TC1044S in the 9V mode, but rather by means of bias point shifting on the FET stages.
Remove the chip and run the circuit using a 9V battery to see if the whine is still there.
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Re: Ramble FX - Marvel Drive 1.0

Postby JabboWookie » 29 May 2018, 11:16

Manfred wrote:
I'm getting a whine from the TC1044S when I'm in 9V mode.


I think that the whine is not caused by the TC1044S in the 9V mode, but rather by means of bias point shifting on the FET stages.
Remove the chip and run the circuit using a 9V battery to see if the whine is still there.


The whine is gone when I pull the chip and run it at 9V (with my PP2+, no battery).
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Re: Ramble FX - Marvel Drive 1.0

Postby PedalPCB » 16 Jul 2018, 19:26

JabboWookie wrote:I built this off of Bugg's PedalPCB Marble Drive, which I'm assuming is based off of this schematic. I'm getting a whine from the TC1044S when I'm in 9V mode. Everything's good in the 18V mode. I've tried two different chips with the same result. Any ideas why this might be happening? Obviously it goes away when I pull the chip.


Add a 10K resistor from the bottom lug of the SPDT to ground, should clear up the whine. This is happening with some charge pumps.

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Re: Ramble FX - Marvel Drive 1.0

Postby plush » 07 Oct 2018, 16:12


I built this off of Bugg's PedalPCB Marble Drive...

https://www.pedalpcb.com/product/marbledrive/


Even though this is not an issue for me, I still can't decide why pedalpcb does not specify the bias voltage in his manual. How on earth would a newb decide on a bias voltage (which should not necessary be 1/2 of the VCC)?
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Re: Ramble FX - Marvel Drive 1.0

Postby J0K3RX » 08 Oct 2018, 00:02

plush wrote:

I built this off of Bugg's PedalPCB Marble Drive...

https://www.pedalpcb.com/product/marbledrive/


Even though this is not an issue for me, I still can't decide why pedalpcb does not specify the bias voltage in his manual. How on earth would a newb decide on a bias voltage (which should not necessary be 1/2 of the VCC)?


I think you unknowingly answered your own question. :thumbsup
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Re: Ramble FX - Marvel Drive 1.0

Postby plush » 08 Oct 2018, 14:27

J0K3RX wrote:I think you unknowingly answered your own question. :thumbsup


Oh, wow, this was unintentional [smilie=sweat1.gif]
Lmao
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