Re: Paralleling Mosfets in smps for Cooler Operation

On 2007-02-15, D from BC <myrealaddress@xxxxxxxxx> wrote:
On Wed, 14 Feb 2007 18:28:31 -0800, Joerg
<notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:

[snip]
Your best friend is the scope. Check out what happens upon turn-on and
turn-off. Also across the Isense resistors (hoping there is one). That
gives you a good indication of whether something is out of whack. Make
sure you don't fry it with any spikes. If in doubt use a resistive
divider so some more sane voltage level.

[snip]

Huhhh...I wish ...I made a damn offline smps.
Can't scope ground it or poof! But it's gotta be done...
(Using a Hickok scope from 1968!! Only 8 knobs :)
I think I have to buy a >100W power transformer (or equivalent
transformer combo) to isolate the smps supply under test. That's going
to cost $$$.

see what you can get at the recycling place, before the invention of the
RCD/GFCI isolating transformers were an essential piece of contractor
equipment and they were built to last.

Last year I got a 1500VA one for $12,

Or brainstorming ideas such as:
Make an optocoupler probe..
Make an op amp differential probe..
Make HF transformer probe..
Buy an isolated digital scope

check what's being chucked first.

--

Bye.
Jasen
.

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