Re: NE555 driven coil WAS:Re: SCR driver coil...

To: tesla-at-pupman-dot-com
Subject: Re: NE555 driven coil WAS:Re: SCR driver coil...
From: "Bill Noble" <william_b_noble-at-email.msn-dot-com> (by way of Terry Fritz <twf-at-verinet-dot-com>)
Date: Wed, 10 Feb 1999 17:04:18 -0700
Approved: twf-at-verinet-dot-com

if you use a dual 555 (I believe that's called a 556), and configure one as
a one shot, and the second as an oscillator to trigger the one shot, you
elimiate the variable pulse width as an issue.  I think the circuit is in
the 555 handbook.  Alternately, I used to use a 2n2222A with a RC network on
the base to make a oneshot, a positive going input is shorted to ground
after the RC time constant - see primitive ASCII schematic below (where
B=base, rrrr=resistor). I used this successfully on SCR triggers for CD
ignitions


+++ input---------rrrrrrrr-------------------- output pulse
                    |                  !
                    |                 |/
                    ---- rrr------|\   2N2222A
                              |         \
                              C        GND
                               |
                           GND
----- Original Message -----
From: Tesla List <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Monday, February 08, 1999 11:35 AM
Subject: RE: NE555 driven coil WAS:Re: SCR driver coil...


>Original Poster: Kerry Jarrell <Kerry-at-apprentice-dot-com>
>
>well I have built a coil this way before, I used a car coil driven with a
>555 timer, the draw back is the 555 timer is not leinar, when you adjust
the
>pulse width the freq changes, a better choice is a pulse width modulator,
it
>is easer to adjust to get the resonant freq out of what ever coil you are
>driving, but you will kill it fast if you do not protect it, I used one to
>drive a high power transisor, you could use a fet, bjt or what ever you are
>used to dealing with...
>kerry
>
>-----Original Message-----
>From: Tesla List [mailto:tesla-at-pupman-dot-com]
>Sent: Friday, February 05, 1999 9:37 PM
>To: tesla-at-pupman-dot-com
>Subject: NE555 driven coil WAS:Re: SCR driver coil...
>
>
>Original Poster: Paolo <pagaiard-at-geocities-dot-com>
>
>