Re: Basic Stamp Controlled Spark Gap

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Crow Leader by way of Terry Fritz <teslalist-at-qwest-dot-net>" <tesla-at-lists.symmetric-dot-net>

Tesla list writes:
>Original poster: "Jeremy Scott by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <supertux1-at-yahoo-dot-com>
> > This will probably need to be modulated so
> > interference is not an issue.
> > 1/4" may even be a bit large of a hole if you want
> > real fine adjustment of
> > your timing or phase.
>I want the hole to look like an electrode.
>If the hole is large, there will most likely
>be a ramp up and ramp down of intensity --
>like during an eclipse :) I should be
>able measure this period accurately, and
>it should be fairly close to what happens
>during the 'real' electrode presentation.
>I realize the real presentation 'rings down'
>and isn't the same wave shape, but their
>time periods should be the same.
> >  > hooked up to an input pin. This will create a
> > stream
> >  > of pulses that can be measured. RPM and electrode
> > face
> >  > time will be calculated in the stamp. The hole
> > will
> >  > be some fixed number of degrees away from an
> >  > electrode, the basic stamp will use this (along
> > with
> >  > RPM) to calculate exactly 'when' a rotating
> > electrode
> >  > passes
> >  > a fixed point.
> >  >
> >  > Speed control -  H-Bridge push/pull type circuit
> >  > using power MOSFETS and an output from the stamp.
> >  > This and the tachometer feedback will keep the
> >
> > I made a leg of a H bridge and scaling it times 4
> > and making a real PCB for
> > it was more of a hassle than just getting a ready
> > made bridge. It was not
> > shielded and has only "crashed" once so far. I'm
> > sure if I put it in a box
> > and kept it more than a few inches from my spark
> > gap, it would be fine
> > forever. Speed control has so far just been a linear
> > taper variable
> > resistor.
> > For a PWM drive, you need want a fixed chopping
> > rate, and a variable on/off
> > timing for each clock cycle. Mine was 2.4kHz because
> > it sounded cool when
> > connected to a speaker. The real controller I ended
> > up using is also 2.4KHz,
> > but some are up in the tens of kHz.
>Did you have an AC or DC motor?

I'm using a cool looking but otherwise boring 24 volt permanent magnet DC 
motor. Making some sort of PWM signal should be very easy with any computer 
device, just vary on on/off duty cycle and repeat this process fast enough 
so that your motor does not make odd buzzing noises (this seemed to 
happened under 2kHz for me with any motor)
KEN