17,5V in 18V E-H effects?

Steben · February 17, 2006, 10:23:15 AM

Still haven't got any answers, so I'm bumping again...
Will 18V fx work consistently on 17,5V (charge-pumped)?
I know the voltage is brought down to 15V inside an Electric Mistress, but is it sensitive to not-exactly-18V?
I just want to make sure!

Peter Snowberg · February 17, 2006, 10:44:53 AM

A charge pump will probably not supply anywhere near the required current.

nelson · February 17, 2006, 11:34:32 AM

There is the LT1054 charge pump that has up to 100ma.

Do a search.

d95err · February 17, 2006, 02:05:12 PM

Such a small variation (about 5%) will probably make no practical difference whatsoever. Can't say for certain, since I'm not sure what circuit you are talking about.

nelson · February 17, 2006, 02:59:05 PM

If you get a regulator that can work at 2.5v over regulated voltage it should be fine.

Mark Hammer · February 17, 2006, 03:15:35 PM

I'm not saying this is the case for the EM, but in some instances, the 18v or 2-battery arrangement is not to necessarily supply 18v to the chips themselves, but to supply enough voltage to some on-board regulator or regulation circuit that, in turn, supplies a stable 12v to the chips. Keep in mind that most BBDs don't really take kindly to supply voltages over 15vdc.

Steben · February 18, 2006, 12:40:03 PM

Quote from: Peter Snowberg on February 17, 2006, 10:44:53 AM
A charge pump will probably not supply anywhere near the required current.

A MAX1044 supllies 200mA, no? I that still not enough for an analog pedal?.....
EDIT: was wrong here...

Still: scott schwarz powers his PT80 (at least 35mA) with a proclaimed 10mA charge pump!
Anyone knows the current consumption of an electric mistress?
MAX660(100mA) works only on max. 6V

Steben · February 18, 2006, 01:19:23 PM

Quote from: Mark Hammer on February 17, 2006, 03:15:35 PM
I'm not saying this is the case for the EM, but in some instances, the 18v or 2-battery arrangement is not to necessarily supply 18v to the chips themselves, but to supply enough voltage to some on-board regulator or regulation circuit that, in turn, supplies a stable 12v to the chips. Keep in mind that most BBDs don't really take kindly to supply voltages over 15vdc.

As I thought, thanks. Still there is the current problem...

Peter Snowberg · February 18, 2006, 07:29:28 PM

OK, maybe current isn't a problem.

Clean current... that may be another issue. I've never been too big a fan of charge pumps for power supplies. I would go the direction of a switching boost regulator.

If there is a 15V linear regulator powered by that pump, a 15V boost regulator gets you there in a single step with greatly increased efficiency. Just substitute one for the other.

http://www.linear.com is my favorite linear IC maker.

Assuming the current is available, it should work fine on 17.5V.

Steben · February 19, 2006, 08:01:49 AM

Quote from: nelson on February 17, 2006, 11:34:32 AM
There is the LT1054 charge pump that has up to 100ma.

Do a search.

Thanks.
Searched, checked and ... ordered samples from TI! I luv their sample program... they should be proud of it.

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17,5V in 18V E-H effects?