RE: why 4 Ohms in PARALLEL with trigger coil primary?

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

Original poster: "Ted Rosenberg by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Ted.Rosenberg-at-radioshack-dot-com>

You raise a good point. Yes, I will check that.
It's possible they are doing...nothing. In which case, out they go.
But save the MOVs, huh?

-----Original Message-----
From: Terry Fritz [mailto:twftesla-at-qwest-dot-net]
Sent: Wednesday, October 17, 2001 12:55 PM
To: Ted Rosenberg; 'Scott.L.Hanson-at-seagate-dot-com'
Subject: RE: why 4 Ohms in PARALLEL with trigger coil primary?


Hmmmmm,

If you but 4 ohms directly across the ac line, it will dissipate 3600
watts...  The dimmer would limit that to maybe 1000 watts...  Something
strange must be going on there.  However, if it works, it works.  But I
think there is a good chance they are blown open which would probably have
little effect.  I would leave it for now and maybe when you can play with
you coil at length, check into it more.  Next time you see the coil, you
may want to double check to see that they really are across the neutral and
hot wires out of the dimmer and not in series.  Check the resistanc if you
can.  I bet it is higher than 4 ohms :-))

Cheers,

	Terry


At 12:40 PM 10/17/2001 -0500, Ted Rosenberg wrote:
>Hi Terry. Hey, if I can type at 6AM (I work from 7 to 4  :)....
>No matter.
>
>The resistance was based on Marc's picking different low values on his
first
>iteration of connections...remember? The 10µF motor run cap and the 10 ohms
>etc. It was about the same time you were using the 250W huge reistors? (I
>have two...any ideas? They do not make good wind chimes!)
>
>Then Marc said that 4 ohms would be OK but he was not terribly clear as to
>exactly where!!
>Well, I didn't have 4 ohms. So two 8's in parallel gave me the 4 <at 40
>watts>. Then I put them in series in the line and I almost burned up the
>coil from the heat. That's when I got hold of you and you suggested across
>the HEI. And that worked.
>
>Does that clarify? Or should I try and followup with Marc?
>
>-----Original Message-----
>From: Terry Fritz [mailto:twftesla-at-qwest-dot-net]
>Sent: Wednesday, October 17, 2001 12:33 PM
>To: Ted Rosenberg; 'Scott.L.Hanson-at-seagate-dot-com'
>Subject: RE: why 4 Ohms in PARALLEL with trigger coil primary?
>
>
>Hi Ted and Scott,
>
>I forwarded this to the Tesla list by accident.  Sorry bout that...  You
>may want to write me at:
>
>terrellf-at-qwest-dot-net
>
>So the sleepy Terry can't just forward all the morning mail on without
>checking who it is addressed to...
>
>I did not understand why the resistors would be in parallel either :o)  I
>thought they should be in series.  I figured, well, I guess it works for
>Ted ok...  You may want to check them with an ohmmeter.  I wonder if they
>blew open in the first second and they are just open now.  If they were
>open, you may not notice (maybe they don't matter...).
>
>Cheers,
>
>	Terry
>
>At 07:02 AM 10/17/2001 -0500, Ted Rosenberg wrote:
>>Hi Scott and thanks for the compliment.
>>I have some answers for you but please understand, as I said in the paper,
>I
>>was the technician. Marc and Terry Fritz deserve the "why" rewards!
>>
>>I originally had the 4 ohms in-line. the resistors got SO hot that they
>>would have burned the wood etc etc. I desparately e-mailed Terry as Marc
>was
>>unavailable. After some discussion, Terry suggested the new position
>>and...it works. I really can't give you a better reason. Sorry. Perhaps
you
>>might ask Terry about that. Who knows, I might learn something  :))
>>
>>I do not own an oscope although I can borrow one.
>>I had to get this coil into the Hangman's House of Horrors and I was
>running
>>out of time. So all seriosu tweaking, checking with scope, adding welders
>>glass etc, will have to wait until the coil returns home after Oct 31.
>>
>>As for the Fan vs Lamp control...while I don't have my ring binder here at
>>the office with my notes, I seem to recall that Terry compared one against
>>the other and found the fan control more robust. And the cost is
>essentially
>>close.
>>
>>Hope I've been of some help.
>>The gap itself is, by all standards, almost a no brainer to build and use.
>>If you can install a lightswitch in a house and solder a kit together from
>>RadioShack, you can build it. No more salient motors.
>>
>>Regards
>>
>>Ted
>>
>>-----Original Message-----
>>From: Scott.L.Hanson-at-seagate-dot-com [mailto:Scott.L.Hanson-at-seagate-dot-com]
>>Sent: Tuesday, October 16, 2001 4:43 PM
>>To: Ted.Rosenberg-at-radioshack-dot-com
>>Subject: TSG: why 4 Ohms in PARALLEL with trigger coil primary?
>>
>>
>>Ted -
>>
>>Nice paper on the low-cost/home brew TSG.
>>
>>I have been experimenting with TSG's (trigatron style) from industrial
>>laser power supplies for switching my 6" X 32", 120ma NST powered coil,
but
>>have been experiencing problems trying to interface with the original
>>trigger circuitry on the TSG driver board.
>>
>>One question on your trigger system schematic. If it is used for current
>>limiting,  why is the 4 Ohm resistor placed across the primary of the
>>trigger transformer, instead of in series with it? This seems inefficient,
>>and subjects the triac to higher loads then it would see from the coil
>>alone.
>>
>>Have you looked at the output with an o'scope to see the change in trigger
>>point, relative to the AC input waveform, as the motor control is varied?
>>If so, how many "degrees" of adjustment are available?
>>
>>Finally, is there anything special about using a fan control vs an
>>incandescent lamp dimmer? Do they both "fire" in any controlled
>>relationship to the input waveform?
>>
>>Regards,
>>Scott Hanson