Re: Where to buy non induction resistors
Posted by
beer@s...
on 2002-03-28 13:07:50 UTC
On 28 Mar, CAD_CAM_EDM_DRO@yahoogroups.com wrote:
The very small inductance of the resistors, IN THIS APPLICATION will be
swamped out by the very large inductance of the steppers.
Now, when used as a sense resistor in a chopper scheme, the story
changes.
Or ...
Replace the resistors with a constant current source. Things will spin
MUCH faster, as fast as any chopper setup with none of the chopper
headaches.
Before you do, though, spend a moment calculating power consumption.
In my case, they were 2 volt 5 amp motors that I was running from a
50 volt supply. The constant current source would therefore have 48
volts across it at 5 amps .. 240 watts per coil .. hmm, where's that
book on chopper design.
However, having some BIG heatsinks around from YAAANC ( yet another
audio amplifier never completed ) and more TO3s than I could shake a
stick at, I did spend the time. It DOES work.
Alan
--
Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta
> Message: 5Almost certainly won't help.
> Date: Thu, 28 Mar 2002 20:28:40 -0000
> From: "lenskeeper2000" <rnichol1@...>
> Subject: Where to buy non induction resistors
>
> Where can I buy non-induction power resistors? I'm using a simple
> L/R style drive circuit and want to step up my voltage but have found
> I have too much inductance to get my speed rate up. I'l thinking if
> I can reduce the effect of the wire wond reisitor's im using this
> will help.
The very small inductance of the resistors, IN THIS APPLICATION will be
swamped out by the very large inductance of the steppers.
Now, when used as a sense resistor in a chopper scheme, the story
changes.
> I've seem lots of power resistors for sale (allied etc.) but noneDigikey sells 5 watt NI resistors .. you could parallel a bunch.
> seem to be non inducting. Looking for 25 watt in the 20-25 hom
> range. Any suggestions?
Or ...
> I'm trying to keep on a budget and am trying to learn electronicsFeel like a designing sort of mood ?
> while upgrading my desktop CNC mill. so holding off going to a
> chopper curcuit as I want to design myself (will leikely eventually
> give in and by Gecko drivers).
Replace the resistors with a constant current source. Things will spin
MUCH faster, as fast as any chopper setup with none of the chopper
headaches.
Before you do, though, spend a moment calculating power consumption.
In my case, they were 2 volt 5 amp motors that I was running from a
50 volt supply. The constant current source would therefore have 48
volts across it at 5 amps .. 240 watts per coil .. hmm, where's that
book on chopper design.
However, having some BIG heatsinks around from YAAANC ( yet another
audio amplifier never completed ) and more TO3s than I could shake a
stick at, I did spend the time. It DOES work.
Alan
--
Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta