Re: Zero Crossing Circuit

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

Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi All - 

Just wanted to report that I built Jon Tebbs Zero Crossing Sync, Variable Delay
Trigger Driver. 

I've fired up the trigger but haven't ran the coil with it yet. Maybe tomorrow.
The circuit worked EXCELLENT right away! I can vary the delay the full range of
the pot. I can hear the HEI trigger vary along the AC half cycle. The energy
out of the HEI is incredible! It "sounds" like a real winner! I ran it for
quite a while scoping out the delay. It appears to be varying the entire 90
degree range, but I'm having a little trouble with this scope. The horizontal
output transisitor (H.O.T.) does get quite HOT, so heatsink it well if you
build this. 

I had everything needed for the circuit from gutted misc. components. I used a
slightly beefier transistor at Q4. Also, I didn't a damping diode (per say), so
I threw a MOT diode it it's place. All other components are either to the
schmetic or very close. For C4, I used 2 Wima caps (SMD6560) in parallel for
0.066uF (possibly the reason for the high energy I'm seeing?). 

I put up a couple photo's of this board at my website. It's not a pretty board,
but at least anyone interested can see the components I used and get an idea of
the circuit. BTW, I also put up John Tebbs schematic. I added dots to junctions
simlpy to clarify overlapping lines and connected lines. 

<http://www.classictesla-dot-com/temp/JT.html>http://www.classictesla-dot-com/temp/
JT.html 

After this email, I'm running out in the garage to fit it into the control
panel. I'll be mounted the centertap transformer and board in the control panel
and  simply running lines out to the HEI at the gap. I'll report back once I
start running the coil with it. 

Take care, 
-- 
Barton B. Anderson 
<http://www.classictesla-dot-com>http://www.classictesla-dot-com 
  

Tesla list wrote: 
>
> Original poster: "Jon Tebbs by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <jgtebbs-at-eos-dot-net> 
>
> Hi Barton, 
>
> > Is this circuit detecting zero-crossing, then delaying "from zero" when 
> the gap will fire? 
>
> This is correct.
> Cheers, 
> -- 
> Jon G. Tebbs 
> <jgtebbs-at-eos-dot-net>