At 08:05 AM 2/05/96 -0500, you wrote:
>Another question to address is how to convert the PIC output level to a
>voltage to run the motor in such a small space?  This doesn't need to be
>solved yet but any ideas from the group would be usefull for planning.
>
That shouldn't be difficult. I have envisaged two approaches. Use an H bridge
chip. One candidate which is available locally in one-ofs is UDN2916EB. This is
a 24 pin gull wing SMT. It has a lot more than I want - it is a dual H bridge
and has some current PWM circuitry. I would like to find a smaller single H
 bridge.
The other alternative is to use 4 PIC outputs to drive a bridge. This will need
4 transistors+4resistors+4 diodes/1 bridge rectifier. This may even be smaller
and definitely cheaper than the single chip solution. Ordinary SMT components
are available at surplus stores at throwaway prices.

What are you using in your command station?

>How small does the decoder have to be?  The one I am using is about 1" x
>3/4" and fits OK in an HO scale locomotive (HO SCALE is 87:1) but won't fit
>in N scale (160:1).
>

I don't know the exact dimensions but I am looking at building it first in HO
and then move to N. Some commercial decoders for N are in two parts to make
installation easier. The N scale loco I have got seems to have enough space for
a decoder about 3/4" x 3/4" x 1/4".

Regards

Prashant
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