Re: SLA7062 technical stuff - supply voltages

On May 11, 2006 06:36 am, Mariss Freimanis wrote:

> 1) Get a 0.022uF/100V capacitor and a 15 Ohm/2W resisitor.

but on May 9th, you said

> I calculated an RC snubber to eliminate this behavior (I = 3A, V =
> 42V, 750nS time constant gives 15 Ohms and 0.05uF).

so I'm curious, .02u or .05u ? Or maybe better still, the formulae used to
derive these values in the first place ?

You see, I've just gotten my hands on some 7062s .. the bare PCBs have been
sitting around for some time, and do have provisions for your recommended
snubber circuitry.

I used 10 ohm 3w and .1uf 250v polyp as a snubber (because I had some, mental
math -never a good thing for me- showed them to be about the right RC, and
mostly, was too lazy to look up your email)

I discovered

a. the 7062s work (at first glance) pretty well, running a variety of steppers
smoothly, and
b. the snubber resistors get pretty darn hot.

Without hauling a scope out and measuring, I would _guess_, based upon the
amount of time it takes for wisps of smoke to appear, that they are
dissipating 5 watts or so ...

Any comments you could share ? (besides "don't be so dumb" .. my wife covers
this admonishment quite adequately !)


Thanks in advance.


Alan

--
Alan Rothenbush
Academic Computing Services
Simon Fraser University
Burnaby, B.C., Canada


The Spartans do not ask the number of the enemy, only where they are.

Agix of Sparta