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Re: Terry's Strobe

LED persistance is VERY short (on the order of nanoseconds).. The real
challenge will be in coming up with a suitable pulsed driver.  Fortunately,
you can run pretty high peak currents through an LED, as long as the average
current is reasonable, so short, bright pulses aren't a problem.

Another idea is to run a Laser Diode pointer off a 6.3 V transformer and a
few diodes in series (to get the voltage reasonable).  The laser will be on
during the top part of one half cycle.  If you have black and white sectors
on your timing disk, you'll get fairly obvious variations in the apparent
brightness of the laser spot as the phasing changes.

-----Original Message-----
From: Tesla List <tesla-at-pupman-dot-com>
To: tesla-at-pupman-dot-com <tesla-at-pupman-dot-com>
Date: Monday, March 27, 2000 10:11 AM
Subject: Re: Terry's Strobe


>Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
>At 10:32 PM 03/26/2000 -0800, you wrote:
>>TCML,
>>
>>I put together Terry's strobe last night and had a
>>chance to try it out. Anyone with a sync gap and
>>twenty bucks should put one of these together:
>>it's a fabulous idea...
>>
>>However, the pulse is kinda wide for 3600 rpm
>>motors. The moving electrodes appear as a blur
>>instead of appear as if they are frozen in time
>>(OK, I could split the difference of the blur, but...).
>>It'd be nice to couple this circuit with a xenon flash
>>to really round out the idea. 120 Hz operation would
>>be nice too. Anyone out there willing to give it a
>>try with me?...
>>
>>Jeff W. Parisse
>>Director, kVA Effects
>>www.teslacoil-dot-com
>>
>
>Hi Jeff,
>
> I was not thinking about 3600 RPM when I designed that :-)  The pulse are
>indeed probably a little wide but you can probably squeak by in a dark
room.
>
> One could redesign it to use perhaps a laser LED or the new white LEDs if
>their persistence is low enough.  The pulse width can be varied over a high
>range but one needs to be carful not to destroy the LED with short high
>current pulses.
>
> Perhaps what you are really looking for would be something along the
>following lines.  You could get a DC timing light from say Sears and
>connect it into a "box" that would provide 12 VDC to run the light and then
>have a trigger pulse to activate it.  120 BPS works out to 1800 RPM on a
>V-8 engine which is well within the strobe lights capability.  The 12VDC
>supply is easy so one would only need to figure out how to fire the timing
>light with a circuit anyone could make easily.
>
> Such a timing light would work in low to mid light so it could be used in
>many "real" situations where total darkness is not available.  Certainly
>not a "low budget" thing considering most cars today don't need timing
>adjusted anymore so the light would really not have any other use for most.
> Perhaps the timing circuit could be as simple as a small extra NST with a
>little gap to make a small spark (a spark plug comes to mind ;-))  Then one
>could just clip the light to the wire but it would have to be really well
>insulated to prevent a short charging the light and the user up to high
>voltage.  I have a little bug zapper transformer that is low voltage and
>low current (relatively) that may be good for this and I have a timing
>light so I'll look into this.  I am not sure the pulse would be really well
>timed in this set up however.  Many possibilities here...
>
>BTW - Jeff, did you ever get E-Tesla5 to figure out you tuning problem?  If
>not catch me off list and I can help out.  I got too busy last week to
>think much about it.
>
>
>BBTW - My strobe instruction are at:
>
>http://www.peakpeak-dot-com/~terryf/tesla/misc/STROBE.ZIP
>
>The pictures are when I had the parts spread out all over the floor ;-))
>You really are supposed to build it into a nice little box.  I "thought" I
>had the completed strobe picture in that file but...
>
>Cheers,
>
> Terry
>
>