1 AMP doesnt even turn my car's motor.

These little things do a 35 meter figure 8 track in under 4 seconds

Also, you Brake by shorting its power leads. A PSU for these will have to
have some serious overload protection built-in

We use several heavyduty 12V batteries wired in parrallel ( for those enduro
envents ).

> -----Original Message-----
> From: pic microcontroller discussion list
> [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Chris Eddy
> Sent: 22 March 2000 07:02
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [OT] PSU for slotcars
>
>
> Quentin;
>
> I find it super hard to believe that these slot cars take 104
> watts each!  I
> strongly suggest you get out there and measure some currents your self.  I
> would never accept laypersons figures in such a matter.  I don't
> doubt there
> are some serious surge currents, but 832 watts is bolderdash!
>
> I would also prepare to measure the current on your scope, with
> an IA across
> a sense resistor (or a hall effect module) to see what the currents really
> look like.  A handheld meter may give you a fantasy.
>
> Let's assume you are now in posession of figures such as 4A surge
> for 800mS
> and 1A continuous.  And the 13V is at full speed, and applies at 1A, not
> 4A.  I would make a constant current source in order to get
> smooth operation
> over dirty tracks.  Assume that the surges all happen at one time, when
> everyone starts out.  The supply needs a beefy hold up cap.
> Further assume
> that the supply will sag some under the starting conditions.  A switcher
> circuit for each controller would allow the user to have constant
> performance through the power supply sags and allow you to
> implement current
> mode control without too much trouble.  Further assume that
> 1A/13V is driven
> by a 24V supply with a buck converter in current feedback mode (not to be
> confused with the current mode implemented in the DC/DC swithch controller
> chip).  13W times 8 is 104W continuous, so use a 200W 24V supply with an
> added 10,000uF cap.
>
> Be careful in the choice of DC/DC controller, you need a variable output,
> where many DC/DC siwtchers are fixed reference.  I solved this
> once using a
> good old LM78S40 (check discontinued) modified the circuit to drive a FET
> and made it a variable output switcher.  A crafty individual might use a
> simple op amp in a feedback loop, driven to instability by an RC in the
> feedback, to make a free oscillating switcher.  Others make
> suitable chips,
> maybe Unitrode, Linear tech, or National.  You could skip the current
> feedback mode if it makes life simpler.  Maybe just put an inductor in
> series with the track line to smooth out the motor operation.
>
> If the switcher is cool enough (.15 * 13 is 2 watts) you might
> sneak it into
> the hand held controller.  Probably depends on the size of the
> inductor and
> capacitors.
>
> Sounds like fun!  I'll be right over.  Africa, right?
>
> Chris Eddy
> Pioneer Mcirosystems, inc.
>
> Quentin wrote:
>
> > A friend of mine asked me about making a PSU for the slotcar track for
> > his club. Seems like these things needs lotsa power. After he gave me
> > the specs I went UHHMMM......
>