Archived from groups: rec.games.pinball (
More info?)
"nomad" <damonoresky@hotmail.com> wrote in
news:1126887257.272656.159660@g47g2000cwa.googlegroups.com:
> Check this thead:
>
>
http://groups.google.com/group/rec.games.pinball/browse_thread/thread/a
> 73dd822872739e4/75f24e487970f792?q=ij+shaker+mod&rnum=1#75f24e487970f79
> 2
>
> I wanted to add this ti my IJ as well but I don't quite understand the
> need for the "mod board" mentioned. If it's just the shaker in line
> with the lamp it would be cool.
Although I haven't seen the board in question, at the very LEAST it's
simply a small driver board. Basically, you're attempting to run a motor
via a transistor that was never sized to do that job, so you need to
'step up' the current carrying capacity with a larger transistor.
i.e. instead of using a tip102, you'd need to use a tip36C. (probably;
again talking a little out of my ass here.) So you feed the output of
the 102 into the 36C (along with power and ground), and essentially "amp
up" the capacity of that circuit.
That's -exactly- the board I made (except with THREE tip36Cs, so I
wouldn't have to use any heat sinks!
) to drive the 'floor flashers'
on my ST:TNG. There's a tip102 normally driving the shield flashers, and
I needed to drive the original three shield flashers plus eight more that
were pointing at the floor. 36C it is!
(again, I used three of them
so that I'd spread the heat out and wouldn't _need_ a heatsink.
Definitely overkill, but 36Cs are fairly cheap in bulk!)
That's why I'm worried about what would happen if the bulb was left 'in
line' with the circuit. Essentially, instead of the input voltage to the
36C dropping to zero 'instantaneously', the bulb will cause it to instead
slew down at a more-or-less constant rate. This would cause the 36C not
to turn on for the full width of the lamp pulse, resulting in shorter
pulses (i.e. less "motor on" time).
------
With all of that said, I _seem_ to remember a motor controller board that
would allow you to specify the 'motor on' time once the motor actually
turned ON. In other words, once the motor turned on, it would stay on
for at _least_ X milliseconds, regardless of what the input was doing.
That would (theoretically) work well in the intended scenario, although
I'm not sure if the design in question has that ability.
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