Re: Basic Stamp Controlled Spark Gap

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

Original poster: "Jeremy Scott by way of Terry Fritz <teslalist-at-qwest-dot-net>" <supertux1-at-yahoo-dot-com>


Wow that's interesting... looks like a spike from
a triac turning on -- do you use the phase-angle
approach method of controlling your motor speed?
('light dimmer' method...)

I thought about using the microcontroller to directly
drive a triac. Would start by setting an output high,
which turns on an opto-relay which turns a triac on.
Another opto relay will be in series with the triac's
main gates and when it turns off (AC crosses 0 into
a new halfcycle), we wait a few milliseconds and turn
it on again. That would probably reproduce the wave
form you have. Infact, I bet if I replaced the
RC network in a light dimmer circuit with a pulse
that's just as wide as it's charge time I'll
accomplish the same thing. The trick is starting the
pulse a few ms after the AC crosses 0.

The new basic stamps support 'interrupts', an
interrupt could be hooked in to run everytime the
AC line crosses 0, (a timing triac turns off) wait a
variable # of microseconds, then set an output high
(turn on load triac).

So it theoretically could 'drive' the speed of the
motor and it would know exactly how fast it's going
without any mechanical sensors. (Would require some
sort of calibration, linear testing etc...)

The same type of 'timing' triac could easily be
used across the tank capacitor's drain resistors.
(Turns off -interrupts the stamp- whenever the
capacitor dumps.)


--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>
 >
 > Hi Jeremy,
 >
 > Check this scope capture of a sync motor's voltage
 > and current:
 >
 > http://hot-streamer-dot-com/TeslaCoils/Misc/SRSG-VI.gif
 >
 > Note the very sharp current spike.  If you could
 > pick of the motors current
 > and high pass filter and detect the spike, you know
 > where the rotor is at
 > ;-))  Might be very easy to do...
 >
 > I could re run this test on my two sync motors just
 > to double check and be
 > sure if you need.  I could also figure out where in
 > the dwell the spike is.
 >
 > Cheers,
 >
 > 	Terry
 >
 >
 >