Re: Simple PSU stuff
Posted by
abbylynx <abbylynx@y...
on 2002-12-13 05:34:55 UTC
Hmmm.. Okay.
I may connect them in parallel as I've noticed that transformers
generally tend to be over-rated (like a 12V transformer delivering
16V etc.), but I won't know until I actually check it with a multi-
meter.
What I was wondering is if they might still have enough juice in
series? I know if they motors were drawing a constant load of power
then the PSU would certainly not be able to deliver enough power, but
bearing in mind that there is a capacitor present to reduce the peak-
loads, and that the chopper will only be delivering "spikes" of power
to the motors, and the fact that the motors are rated 2A at 3.2V, I
would tend to think that the PSU would be able to keep up, since the
capacitor would still be able to be recharged enough to maintain the
load.
Or am I overlooking something?
Thanks for the advice!
--- In CAD_CAM_EDM_DRO@yahoogroups.com, "echnidna <echnidna@y...>"
<echnidna@y...> wrote:
motors. On each full step 2 amps will flow through each of the motors
coils making a total of 4 amps per motor or a total of 12 amps for 3
motors. This does not allow for fan current.
dc.
would probably improve the performance it may not be necessary as
various factors including your machine design all inter-relate.
you were only using say half the rated current of a transformer its
quite possible the larger capacitor could deliver a higher output
voltage, perhaps up to say 19 volts dc, as it would be working higher
up the rectified sine curve and resistive losses etc in the
transformer would be lower due to a lower current.
peak performance.
fuse.
I may connect them in parallel as I've noticed that transformers
generally tend to be over-rated (like a 12V transformer delivering
16V etc.), but I won't know until I actually check it with a multi-
meter.
What I was wondering is if they might still have enough juice in
series? I know if they motors were drawing a constant load of power
then the PSU would certainly not be able to deliver enough power, but
bearing in mind that there is a capacitor present to reduce the peak-
loads, and that the chopper will only be delivering "spikes" of power
to the motors, and the fact that the motors are rated 2A at 3.2V, I
would tend to think that the PSU would be able to keep up, since the
capacitor would still be able to be recharged enough to maintain the
load.
Or am I overlooking something?
Thanks for the advice!
--- In CAD_CAM_EDM_DRO@yahoogroups.com, "echnidna <echnidna@y...>"
<echnidna@y...> wrote:
> Assuming each motor may operate simultaneously, the transformer foryour power supply is not large enough to handle 3 - 2 amp bipolar
motors. On each full step 2 amps will flow through each of the motors
coils making a total of 4 amps per motor or a total of 12 amps for 3
motors. This does not allow for fan current.
>amps at 12 volt ac. After rectification you will have about 17 volts
> If you parallel connect the transformer coils you will get 12.6
dc.
> Depending on type of drivers this may be quite ok as the supplyvoltage is over 5 times nominal motor voltage. Though higher voltage
would probably improve the performance it may not be necessary as
various factors including your machine design all inter-relate.
>using a 47000uf capacitor could help reduce ripples a bit more. If
> The minimum capactor size should be 2000uf per amp or 24000uf, so
you were only using say half the rated current of a transformer its
quite possible the larger capacitor could deliver a higher output
voltage, perhaps up to say 19 volts dc, as it would be working higher
up the rectified sine curve and resistive losses etc in the
transformer would be lower due to a lower current.
>very well or you may have to get a bigger transformer to get absolute
> If it was me I would try it out and see what happens, it may work
peak performance.
>twice the size of the current, so a 2 amp system should have a 4 amp
> Regards
> Bob Thomas
>
>
> The conventional size of a fuse in a normal electrical circuit is
fuse.
>wrote:
> Regards
> Bob Thomas
>
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...>
> >two
> >
> > abbylynx wrote:
> >
> > >Hello again Folks,
> > >
> > >I have a nice heavy toroidal transformer here, rated 160VA, with
> > >windings of 12V @ 6.3A each, a 20A full-wave bridge rectifier(100V
> > >or 200V I think), and a big 50V 47,000uF capacitor. I'm going tohook
> > >the windings in series, to get 24V. I want to build a power-supply,
> > >but am wondering if I need to use bleeders on this? I'll also beof
> > >chucking a 24V fan onto the whole rig, so that should do the job
> > >bleeders right?almost
> > >
> > >
> > The problem is you will get 33.9 V out, as the 12 V rating is
> > certainly RMS, the equivalentresistive
> > heating power you would get from such a transformer into a
> > load. But, the rectifierRMS
> > charges the capacitors to the peak voltage, which is 1.414 x the
> > equivalent.DC
> >
> > That will likely be great for a stepper drive, but may smoke your
> > fan. You could putto 24 V.
> > 14 1 Amp diodes in series with the fan to drop the voltage down
> >motors,
> > >As for the load, it'll be 3 bipolar drive 2A, 3.2V stepper
> > >ala the type Sherline provide. Should be enough juice, no?recommended?
> > >
> > >The next question, what rating and type of fuse would be
> > >Should I put fuses on all the motors grounds, or would one singlepower
> > >one be sufficient?
> > >
> > >
> > Certainly DON'T fuse the grounds. That could cause all sorts of
> > problems, depending on the
> > exact design of the stepper drivers. You want to fuse the (+)
> > input to the stepper drives,could
> > in most cases. Don't put fuses on the motor wires at all, this
> > damage the stepperdriver gives
> > drivers if the fuses ever pop. If the maker of the stepper
> > such info, that wouldramifications.
> > be the best authority. If not, there can be all sorts of
> > For instance, withcapacitor
> > Gecko drives, you should put a large, low-ESR electrolytic
> > directly on thepower
> > Gecko power terminals, and have the fuse between that and the
> > supply. Fusesdevices like
> > present substantial resistance, and can cause problems with
> > stepper driversstarting
> > that draw power in short current bursts.
> >
> > As for size, probably a 3 A standard-blow fuse would be a good
> > point. It iscurrent in
> > unlikely that the drive will ever draw more than 1.5 x the
> > one motor winding,save
> > unless you run it at very high speeds. Anyway, the fuse will not
> > the drives fromtransistor has
> > most breakdowns, it is there to stop current flow AFTER a
> > blown.the
> > This will limit the fireworks substantially if a transistor in
> > driver fails.
> >
> > Jon
Discussion Thread
abbylynx <abbylynx@y...
2002-12-12 08:10:36 UTC
Simple PSU stuff
Robert Campbell
2002-12-12 12:46:19 UTC
Re: [CAD_CAM_EDM_DRO] Simple PSU stuff
turbulatordude <davemucha@j...
2002-12-12 14:25:13 UTC
Re: Simple PSU stuff
Jon Elson
2002-12-12 23:11:28 UTC
Re: [CAD_CAM_EDM_DRO] Simple PSU stuff
echnidna <echnidna@y...
2002-12-13 03:00:48 UTC
Re: Simple PSU stuff
echnidna <echnidna@y...
2002-12-13 03:50:52 UTC
Re: Simple PSU stuff
abbylynx <abbylynx@y...
2002-12-13 05:34:55 UTC
Re: Simple PSU stuff
Carol & Jerry Jankura
2002-12-13 06:20:16 UTC
RE: [CAD_CAM_EDM_DRO] Re: Simple PSU stuff
JanRwl@A...
2002-12-13 10:20:17 UTC
Re: [CAD_CAM_EDM_DRO] Re: Simple PSU stuff
JanRwl@A...
2002-12-13 10:29:29 UTC
Re: [CAD_CAM_EDM_DRO] Re: Simple PSU stuff
Mariss Freimanis <mariss92705@y...
2002-12-13 15:10:33 UTC
Re: Simple PSU stuff
echnidna <echnidna@y...
2002-12-14 02:43:31 UTC
Re: Simple PSU stuff
JanRwl@A...
2002-12-14 18:00:05 UTC
Re: [CAD_CAM_EDM_DRO] Re: Simple PSU stuff
david_mucha <david_mucha@y...
2003-01-16 19:44:11 UTC
stepper voltage ( was Re: Simple PSU stuff
Mariss Freimanis <mariss92705@y...
2003-01-16 21:44:37 UTC
stepper voltage ( was Re: Simple PSU stuff