No Variac Warning! Re: [sdiy] Lifespan of Electrolytics?

[oleavitt at ix.netcom.com]

Hello,

In your warning, did you mean a Triac?
Electronic power cotrollers will definitely not work predictably with transformers unless they generate a true sine wave.

I've used a variac many times for controlled testing and never had problems. Using a variac has spared me a room full of smoke many times - especially when powering up old gear that hasn't been powered up in 40 years.

Regarding frequency, iirc, there was a thread a while back about somebody trying to run an o-scope that was wired for 400Hz circuit on a standard 60Hz circuit...

On Mon, 20 May 2002 11:48:09 -0700 Cynthia Webster <cynthia.webster at gte.net> wrote:

Hi 

I wouldn't advise using a Variac with anything using a transformer!!
(Variac to transformer = Heap Bad Mojo)!

DO NOT TRY HIS AT HOME!
(well, maybe in the kitchen if you have a nice apple pie in the oven)

Seriously folks
The windings of many a transformer are simply not designed for
anything other than a standard mains supply from the wall.

Playing with the voltages or frequency of the voltage is not advised!
Bringing a power supply "up to operating voltage" with a Variac is
much more likely to cause problems - than to solve them...

There are a few electronic speed controls that may work,
however the majority of them do not.  So be warned!
This applies to florescent light ballasts (transformers),
and most motors as well.


on 5/20/02 11:22 AM, Tim Ressel at madhun2001 at yahoo.com wrote:

> Yo,
> 
> I have heard tales of woe concerning electrolytics.
> One story is that if they are run with a significant
> percentage of the working voltage, something bad will
> happen. I'm not sure I believe that. Another concern
> is electrolytics that have not been used for a long
> time. The electrolyte 'goes bad' somehow. You're
> supposed to bring the voltage up slowly when firing up
> a unit after a long idle period, to 'reform' the
> electrolyte. 
> 
> I have had none of these problems. However, when I
> received my used Heathkit tube power supply, I brought
> it up slowly with a variac, just to be safe.
> 
> Does anyone have a circuit for testing caps??
> 
> --TR
> 
> 
> No Variac Warning!   Re: [sdiy] Lifespan of Electrolytics?