piclist 1996\04\26\034804a >
Thread: Pic code protection alert!
face BY : John Payson email (remove spam text)

> A new standard, DCC, has been established for model trains. The signal is
> sent through the tracks. Normally the train has connections going directly
> from the tracks to the motor and you control speed and direction by
> controlling the voltage on the rails. But in this case, a decoder sits
> in between and decodes the packet and drives the motor appropriately.
> Now the decoder should fit inside a train and the scale of the train
> defines the magnitude of the problem. I model N scale which is 1:160
> and believe me when I say tiiiny I mean every i in that word.

N scale is 1/2 of HO, right?  So you're looking at putting your control in
a space about 0.4"x0.4"x0.8"?  That's not very big...

Normally my inclination for controlling a model railroad would be to use a
single power-switching transistor and a direction-switching relay.  When
space is not a problem, this will save components and may save cost (esp. if
you'd want to opto-isolate things).  In your case, however, there isn't really
room for a relay. :-(

Given that, I expect your best bet may be to produce a 3-board stack.  The
bottom board will contain two SOTs on each side; the next board would contain
the rectifier for the PIC power supply, and two SOTs (which would switch the
high-side SOT's on the bottom board).  The top board would contain the PIC and
resonator on one side, and the filter caps and regulator for the PIC's supply
on the other.  By my figuring, this should all (barely) fit in the space you

My other recommendation: switch to O gauge :-)

In reply to: <199604260526.PAA21677@mailhub.rta.nsw.gov.au> from "Prashant Bhandary" at Apr 26, 96 03:26:37 pm
See also: www.piclist.com/techref/microchip/devices.htm?key=pic
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