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Re: electronics question for the tech-heads.

In this case I think it would be risky to even try it.  The GK pickup does
not provide it's own power - power, I believe, comes from another device
such as a GR33 or VG-8.  In the configuration you want to try, the GK
pickup would merely let power flow through it and into the sustainer
circuit.  A hunch tells me that the sustainer circuitry requires more
amperage than the GK does to operate.  Thus, I doubt the GK power supply
is rated for powering a GK pickup and a sustainer circuit simultaneously. 
If sufficient over current protection is not built into the device that
provides GK power, you could very well burn something up not in the GK
pickup, but whatever device is providing GK power.

Checking amperage is not something you can do simply with a multimeter in
this situation.  You'll have to somewhere make a break in the wire that
carries power to the GK pickup and insert the multimeter in series with
the flow of power (when you measure voltage you're actually connecting the
meter in parallel with the circuit under question).  However, an amperage
measurement only tells you how much current is being drawn by a device -
it tells you nothing about how much current the power supply is capable of
providing (only the power supply manufacturer can tell you that).

If it were me, I'd modify my guitar to make the sustainer battery as
easily accessible as possible, always make sure I have a backup battery,
and teach myself the habit of unplugging the guitar when won't be played
for a long duration.  I treat batteries like strings - always have a

Another option - find a wall wart power supply that is capable of powering
the sustainer circuit, attach a long cable to it, put a power connector on
your guitar, and wail away.

Best of luck,

> Good point Brian, but would it be risky to "try", could i blow something?
> Checking thru the spec of the GK pickup (that would be providing the
> power) there is no mention of power requirments at all, I guess it has 
> user servicable parts" therfore no info...
> (how do i check the amperage anyhow?my simple multimeter doesnt seem to
> have that on it..)
> Mark
>   Risky...You also have amperage to consider. Will the source be able to
> handle the amperage that the pickup draws?
>   I think your best bet is to contact the manufacturer for the specs.
>   Brian
>   ----- Original Message -----
>     From: mark francombe
>     To: loopers-delight@loopers-delight.com
>     Sent: Friday, February 11, 2005 4:33 PM
>     Subject: electronics question for the tech-heads.
>     Sorry for Off topic..
>     After a few weeks of completely happy and crazy use of my newly
> installed (and now working, thanks to LD people) Fernandes Sustainer
> pickup, I have for the first time left the damn thing plugged in
> overnight, (battery switch on jack socket arrangment) and drained the
> battery. THIS WILL NOT DO! now I could add a power switch to the
> guitar (but then I would no doubt forget that ..)
>     BUT... I have a cunning plan!!!
>     I also have a GK midi pickup installed on the same guitar, and when I
> poke around with the multimeter at the socket that is installed in the
> guitar that takes the midi to my synth I find a pin that seems to have
> around 7 volts sitting there. The sustainer pickup taks a 9 volt
> battery (but when I test, again with multimeter) it also appears to be
> around 7 volts.
>     Now it doesnt take an idiot to realise what I'm suggesting. I would
> like to take the power from the GK midi pickup cable and connect it to
> the sustainer. Which I would have tried already, but for one little
> prob.
>     If I check voltage on the battery with multimeter connected with 
> cable to ground and RED cable to battery.. 7 volts. When I do the same
> on this mysterious power wire inside the GK connector, the multimeter
> trys to swing the wrong way, I reverse the multi meter leads, and then
> I get this reading of 7 volts.
>     Does this mean that the GK pickup is infact powered by -(minus) 7
> volts? ( I've never really understood the concept of negative volts Im
> afraid..) SO.. either I cant use this power, OR I must reverse the
> polarity of it???
>     Is this possible?
>     Wise?
>     Foolish?
>     Help?
>     Mark
>     mark francombe
>     www.markfrancombe.com
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