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Re: [TCML] quench times again
Hi Bart,
I think its got confusing as we are talking about the entire system in one
go. Though that is the problem, alter one thing and you mess up else where.
What I set out to find out in the first place was in terms of frequency and
conduction time across the spark gap. I will probably repeat myself a fair
bit though with so much confusion going on it may help to recap at this
point...
If all factors being the same, 10 cycles for example at 100khz will take
100uS to pass though the spark gap. this is our first notch quench. Now
given now that all factors being the same, that we progress to 200khz and it
will still take 10 cycles but the conduction time will be reduced by 50%
across the spark gap.
This probably does not sound too interesting at this point, though if we
loose 1% in losses per cycle then we will still probably loose the same % as
there is the same number of cycles. Though overall the spark gap has only
operated for 50uS not 100us. So in some small way efficiency should go up.
Higher frequency should ionise the gap faster and help reduce conduction
losses per cycle also.
The next problem was related to the higher frequency in itself, ok, I know a
little better now and mutual inductance is a big factor too. higher
frequency not only ramps up the secondary faster but its higher frequency
should also help ionise streamers output also. Higher frequency is higher Q
coils. less secondary resistance, less turns, should help pump more current
into the sparks also. Also help drain the tank cap faster.
The next problem related to frequency is really it needs a higher input
voltage rather than current. maybe 20KV tank cap and below 50nF. Current in
the spark gap is rduced due to the lower tank cap value which is good.
However there will be less primary turns so current will increase in that
respect. Now if you went form a 10KV 200nF tank to 20KV 50nF then really you
have 4 times less current. so you can pull 4 more more current with the
primary, sort of in relation to a 20KV 200nF system.. well not really....
If 50nF can quench 4 times faster than 200nF, then this is a good gain. You
can afford to increase the current pulse 4 times and the spark gap should
quench just the same as a 10KV 200nF system. Our new system 20KV 50nF. Now
the primary inductance may limit to 100amps on the 200nF 10Kv system, but
you could afford to get away with 400amps on 20KV 50nF.
The idea really is that a higher frequency should allow a higher current
pulse with upsetting the RSG too much. It was also my point about "making
sure" by decreasing the RSG dwell time. As higher current will be harder to
quench, then decrease the dwell time and it should help matters also.
A lot of factors come into play, as pointed out by yourself, John, etc.
Though this was really the overview of the "high Q" system which I had in
mind. A lot of ideas and corrections brought up in all these posts thats for
sure!
Everyone has been down the classic road, wider coils, more inductance,
larger toroids... So I am thinking of a "new" direction instead....
Another point which has not come into it yet, even though I mentioned it.
Higher frequency should also increase efficiency in it its own right
for example, running from a 12V test setup, at 15cm "range" ....
50hz =0
39khz =0.5mV
124khz=5mV
1mhz =50mV
1.2mhz =70mV
1.43mhz =120mV
1.87mhz =150mV
2mhz =200mV
I was wondering if this would also apply to coupling efficiency. In a way
it looks like voltage is lost over the coupling. Tighter coupling would in
effect reduce my "range" figure and double up on the voltage.
After a lot of testing I drew up that double the frequency gave x4 the
voltage output. As a relation, 10 times the frequency gave double the
"range".
Going by these figures, if a normal tesla coil used 1,000 turns at 100khz,
then it suggests a magnetic field which runs "out of steam" at 1,000 turns.
So increasing turns does nothing at all other than to gain a few volts and
increase resistance.... the point now that if we progressed to 1mhz then we
should be able to use 2,000 turns and the magnetic field will run "out of
steam" at the 2,000 turns mark.
Also as frequency goes up you get more voltage. take 124khz 0.5mV to 1mhz
50mV . This is all at 15cm "Range". When I say range, I mean the distance
between the primary and secondary. Remember only the frequency changed and
the voltage was constant at 12V.
It is one of those odd things which also confuses me about tank energy going
from primary to secondary. My own tests show there is a voltage drop... if
we take 124khz I input 12V and got 0.5mV output.
Another problem is that Q factor was not taken into account with the
secondary. I used a variable capacitor to tune the secondary to the primary.
So Q factor probably was going up.. Though in anycase frequency increase
gave way to higher Q factor coils and gave greater efficiency.
Even though I still have more tests to do. I got 16mhz as being the best
solution. I made me first think that the secondary coil over the loose
coupling would only obtain a fraction of the voltage. In which case energy
would be lost over the distance between the primary and secondary coils....
always interesting none the less!
Chris
----- Original Message -----
From: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Saturday, November 24, 2007 8:01 PM
Subject: Re: [TCML] quench times again
Hi Chris,
Another correction I need to make.
As the number of cycles increases, the transfer rate will "decrease".
What you are doing is interesting and how you are going about looking at
how the frequency affects the transfer rate, efficiency, and gap
conduction. Very interesting subject to me.
Take care,
Bart
As the number of cycles increases, the transfer rate will increase. Here
is the relationship.
Total Energy Transfer = (0.5/((1/(1-k)^.5)-(1/(1+k)^.5)))*(1/fr)
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