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Powering 10 volt pedal with 9?

Postby ManFromGlass » Mon Mar 16, 2020 3:24 pm

I have an old DOD Buzz Box. It takes a 9 volt battery or 10 volts from an adapter. If my multi pedal power supply can supply 9 or 12 volts I think it makes sense to use the 9 volt option. I assume 12 volts could cause damage either long or short term. Thoughts appreciated.
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Re: Powering 10 volt pedal with 9?

Postby Hugh Robjohns » Mon Mar 16, 2020 3:41 pm

They probably specify a 10V external PSU because they're using simple routing diodes to switch between the internal battery and external supply (in which case you'd lose 0.6V across the diode).

So if you use a 9V external supply the circuitry will presumably see something closer to 8.5V, and thus sound the same as when operating on a partially run-down battery.

I suspect it would actually be fine running on a 12V supply too... but without seeing the actual circuitry Ican't guarantee that... so I'm not recommending it!

H
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Re: Powering 10 volt pedal with 9?

Postby ManFromGlass » Mon Mar 16, 2020 6:17 pm

Thanks Hugh. This is wonderfully nasty sounding pedal so it might sound even cooler being partially starved!
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Re: Powering 10 volt pedal with 9?

Postby ef37a » Mon Mar 16, 2020 6:24 pm

http://guitar-fx-layouts.42897.x6.nabbl ... 30721.html

9, 10 or 12V I would not worry. The pedal appears to use standard FETs, bipolar transistors and a common op amp.

Pedals to be wary of are those with 'time' functions and use the old bucket brigade chips.

Of course make absolutely certain the polarity is correct.

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Re: Powering 10 volt pedal with 9?

Postby ManFromGlass » Mon Mar 16, 2020 6:39 pm

It’s an 1/8 inch plug with centre pin positive. I will triple check with a voltage meter before inserting. For some crazy reason this pedal is very desirable currently. Now I couldn’t afford to replace it. Years ago the used price was very affordable. Go figure.

Great link - btw - I wish I had the gift of being able to assemble electronics that work.
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Re: Powering 10 volt pedal with 9?

Postby ManFromGlass » Wed Mar 18, 2020 2:48 am

a question about mA -

Online I found a picture of the wall wart for this pedal and it says 300 mA but the isolated power supply I am trying to hook all my pedals up to can do 100 mA, 250 mA or 500mA.
Would 500 mA be the correct choice? In the process of determining the correct pin polarity I think I blew up a fuse in my tester.
:headbang:
So I'm not turning on any power until I have the milliamps figured!

Thanks.
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Re: Powering 10 volt pedal with 9?

Postby Hugh Robjohns » Wed Mar 18, 2020 3:00 am

It's normal for the power supply to be able to provide (slightly) more current than the load device actually needs. So depending on how over-specified the original PSU was, you might possibly get away with the 250mA option, but the 500mA mode is far more likely to work correctly.
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Re: Powering 10 volt pedal with 9?

Postby ManFromGlass » Wed Mar 18, 2020 3:11 am

Thanks!
I found another photo of a different version (but same model number) of the power supply from the same company. It says 10 vdc and 150 mA. The first picture says 9.6 vdc 300 mA.
I should have taken electronics instead of electricity in high school. I will give all a try. My big fear was to blow up components in the pedal.
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Re: Powering 10 volt pedal with 9?

Postby ef37a » Wed Mar 18, 2020 9:01 am

ManFromGlass wrote:Thanks!
I found another photo of a different version (but same model number) of the power supply from the same company. It says 10 vdc and 150 mA. The first picture says 9.6 vdc 300 mA.
I should have taken electronics instead of electricity in high school. I will give all a try. My big fear was to blow up components in the pedal.

Just spotted that the pedal uses a logic chip, 4013A but even so I doubt the whole thing draws more than 150mA (that's 0.15 amps) The chip also has a maximum voltage rating of 20V so 12V is not going to bother it one bit.

Best to check that those PSUs are 'Switch Mode Power Supplies' because these are 'regulated. That means they deliver the same voltage regardless of the current drawn by the pedal. Most are SMPSUs these days because they are much more efficient, i.e. 'Greener'.

If you are really stuck MFG PM me for a bit of 1on 1. I can post any info that might result and help others once you are up and doing.... NOT supposed to freaking go out anyway!!

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Re: Powering 10 volt pedal with 9?

Postby ManFromGlass » Wed Mar 18, 2020 2:17 pm

Thanks for the offer, Dave. I think I’m in good hands with the main power supply. I bought a True Spot CS 12 which is overkill but has room to grow. My main fear was blowing something up because of my limited knowledge of electronics and I think I’m ok now. But as I go down this fun pedal rabbit hole I may have another technical question or two.
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Re: Powering 10 volt pedal with 9?

Postby James Perrett » Wed Mar 18, 2020 3:24 pm

ef37a wrote:Just spotted that the pedal uses a logic chip, 4013A but even so I doubt the whole thing draws more than 150mA (that's 0.15 amps) The chip also has a maximum voltage rating of 20V so 12V is not going to bother it one bit.

The 4000 series of CMOS logic chips consume only a few microamps - we used to use loads of them in our battery powered oceanographic instruments. I'm surprised to see an A version specified though - the B series are more common and better protected.
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Re: Powering 10 volt pedal with 9?

Postby Wonks » Wed Mar 18, 2020 3:46 pm

James Perrett wrote:The 4000 series of CMOS logic chips consume only a few microamps - we used to use loads of them in our battery powered oceanographic instruments. I'm surprised to see an A version specified though - the B series are more common and better protected.

The Buzz box is basically two pedals in one. Apparently the sub-octave fuzz part of the circuit of the Buzz Box is a direct lift from the MXR Blue Box of 1974. Could the age of the circuit have something to do with the chip selection?
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Re: Powering 10 volt pedal with 9?

Postby ef37a » Wed Mar 18, 2020 4:02 pm

James Perrett wrote:
ef37a wrote:Just spotted that the pedal uses a logic chip, 4013A but even so I doubt the whole thing draws more than 150mA (that's 0.15 amps) The chip also has a maximum voltage rating of 20V so 12V is not going to bother it one bit.

The 4000 series of CMOS logic chips consume only a few microamps - we used to use loads of them in our battery powered oceanographic instruments. I'm surprised to see an A version specified though - the B series are more common and better protected.

This is the dirty world of guitar electronics James! "better protected" means more expensive!

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Re: Powering 10 volt pedal with 9?

Postby James Perrett » Wed Mar 18, 2020 4:26 pm

Wonks wrote:The Buzz box is basically two pedals in one. Apparently the sub-octave fuzz part of the circuit of the Buzz Box is a direct lift from the MXR Blue Box of 1974. Could the age of the circuit have something to do with the chip selection?

That would explain it - I think the B series appeared in the late 70's and were the latest thing when I started in the business in 1980.
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