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Re: TSG instability



Original poster: "rheidlebaugh by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rheidlebaugh-at-zialink-dot-com>

Antonio : I had  a transistor driven ignition for a motor cycle that had a
similar problem. every time a CB was transmitted near my bike My engine shut
down. Interfearance as voltage is increased could easly cause a similar
problem in the timing circuit.

> From: "Tesla list" <tesla-at-pupman-dot-com>
> Date: Fri, 01 Mar 2002 22:01:58 -0700
> To: tesla-at-pupman-dot-com
> Subject: Re: TSG instability
> Resent-From: tesla-at-pupman-dot-com
> Resent-Date: Fri, 1 Mar 2002 22:20:45 -0700
> 
> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
> 
> Tesla list wrote:
>> 
>> Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <Gary.Lau-at-compaq-dot-com>
>> 
>> It appears that this is not as mysterious as I had feared.  Dragging out
>> the digital scope, I observed the 556 timer output that triggers the SCR
>> that fires the trigger xfmr.  When the Variac is less than ~75%, the pulse
>> train is as expected - one pulse every 8.33 msec.  But when the Variac is
>> cranked up, there are often two pulses per half-cycle, the second one
>> coming maybe 1 msec after the gap fires.  And on cycles where when the gap
>> misfires, the first pulse is missing.
>> 
>> Some further circuit design work is going to be needed to curb spurious
>> pulses and stabilize things.
> 
> I once tried to make an ignition coil driver controlled by a monostable
> circuit, so that I could produce just one spark, at a time controlled
> by an external signal. This is the same case of a TSG.
> I observed that the spark of the ignition coil (not to mention the spark
> of a triggered Tesla coil soon after) was causing strong interference,
> that could easily trigger again the monostable. The result was a series
> of sparks instead of just one.
> The solution was to add another monostable, triggered by the fall of the
> first one, and wired so that during its pulse the first monostable could
> not be triggered in any way. With the pulse of this second monostable
> lasting for more time than the operation cycle of the ignition coil, and
> of the triggered circuit, the driver was kept inactive and insensitive
> to interference.
> I didn't use ICs in the circuit, but I'm sure that two 555s can be wired
> in the same way.
> 
> Antonio Carlos M. de Queiroz
> 
> 
> 
>