Re: Voltage Regulators or Diodes to drop voltage?

One method is to use an isolation transformer. this would (should
allow you to drop a couple volts, but it is double parts and it would
be as big as your current transformer.

I Variac would do the same, but you are again stuck with a double
unit.

A simple 110vac switcher power supply would allow you to drop your
voltage a few votls and since you have a tranformer and cap, you
already have the needed isolation from the noise.

as another idea, a diode in each line would limit the watts disapated
over multiple devices.

Seesm you got too much of a good thing !

Dave



--- In CAD_CAM_EDM_DRO@yahoogroups.com, "abbylynx <abbylynx@y...>"
<abbylynx@y...> wrote:

> Hi again,
>
> Well, my linear power supply is working well. Too well in fact..
> after the bridge recifier and capacitor, it's pumping out 38 volts.
> This would be fine, only that the maximum voltage limit on my

driver

> board is 35V. Aaah!
>
> Anyway, I need to drop off about 4V or so, just to be safe. Any
> advice? I know I could just open the transformer and start taking
> windings of the secondary, but (A) it's tedious as hell, (B) it's
> probably defeats the isolation (my duct-taped result would

certainly

> not be as isolated as the original) and (C) ... it's just plain not

a

> good idea.
>
> So I was wondering about other avenues? I'd heard someone talking
> about using Diodes to drop the voltage on the line? What diodes do
> you use for this and how many? (I can no longer find the message)..

I

> have some diodes around, but they're all meek li'l 1AMP ones,

they'd

> certainly become a small short-lived heating element on the 7AMP
> power supply.
>
> Also, what about voltage regulators? I know they don't make

anything

> above the 7805 and 7812 (no 7824).. but I know there are variable
> ones available where you can set the output voltage with a

resistor.

> Again, looking on the web I've only been able to find some meek

li'l

> 1.5ampers - which'll no doubt be carbon-toasties(tm) by the time my
> steppers have vamped it. A voltage regulator would seem good -

since

> it might just save the driver board in the event of the AC power
> supply jumping up a few volts in a surge etc.
>
> Any advice welcome!
> Thanks. :)