At last !  An answer from someone who has a slot car power system.

Seriously though, this has always been the traditional answer - use some car
batteries to run the slot cars, one (or more) per slot car.  The better
systems would use continuous, monitoring chargers for each battery.

So what would you need for 8 tracks . . .
8 deep cycle batteries
8 isolating diodes
8 battery charger circuits set to 14.5V (13.8 + diode drop of 0.7V) @ 1.2A
2 rectifiers
2 transformers  (18V @ 6A)

Except for the batteries I would estimate that this could be built for about
AU$300 (US$200).  Then there are the batteries.  Car batteries are
unsuitable - they are designed to give a big push for a short time and be
recharged *IMMEDIATELY*. Deep cycle batteries are designed to provide
moderate output for long periods, but must not be discharged too deeply,
(discharged to only about 5% below max is recommended for maximum life).

6 hours continuous flat-out running of a slot car drawing an average 4A (3.2
from battery & 1.2 from charger) uses 19.2AHr, and can be replaced over 18
hours at 1.2A from the charger (21.6Ahr).  This would drain the battery by
around 3.2A x 6Hr = 19.2Ahr.  Of course actual usage would normally be less
than an average of 4A so the power usage time would be spread over a longer
track usage time, probably around 9 or 10 hours per 24.

So you need to buy batteries with at least 400Ahr capacity to keep the
discharge per cycle drop below 5%.  (Each extra 5% discharge per cycle
halves battery life - that is a battery regularly discharged to 10% below
max will only last half as long as one regularly discharged to 5% below max.
If discharged to 15% below max per cycle it will only last a quarter as long
as a 5% discharged per cycle).

400Ahr deep cycle batteries are about AU$150 each (US$100).  And you need 8
of them.  That makes a total of AU$1500 (US$1000) for 8 tracks *AND* you are
up for another AU$1200 (US$800) every 4 or so years.

No wonder your friend wants an electronic solution.  So can anyone suggest a
proper solution.  What we need is a 14.5V @ 80A (1200VA) low droop power
supply with 8 isolating diodes and 8 capacitor tanks.

Don't be afraid to suggest expensive solutions (see cost of alternative,
above).

Bye.

        -----Original Message-----
        From:   John De Villiers [SMTP:bbj@PLZ.CO.ZA]
        Sent:   Monday, 27 March 2000 0:10
        To:     PICLIST@MITVMA.MIT.EDU
        Subject:        Re: [OT] PSU for slotcars

        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 ).

        > 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......
        >