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Re: KV's and multimeters [555]
From: Joshua Resnick[SMTP:seraphim-at-WPI.EDU]
Sent: Sunday, November 23, 1997 10:17 AM
To: Tesla List
Subject: Re: KV's and multimeters [555]
Tesla List wrote:
> From: Bill Noble[SMTP:william_b_noble-at-email.msn-dot-com]
> Sent: Friday, November 21, 1997 11:37 PM
> To: Tesla List
> Subject: Re: KV's and multimeters
>
> the 555 doesn't have enough drive current to run a 3055 - use a 2222
> or some
> other device as a driver. remember, the base current is the collector
>
> current divided by the transistor's beta (I know, that's too simple,
> but it
> will get you started) - it's safe to assume a beta around 10, your "tv
>
> transistor" could have been a darlington - some are.
> -----Original Message-----
> From: Tesla List <tesla-at-pupman-dot-com>
> To: 'Tesla List' <tesla-at-poodle.pupman-dot-com>
> Date: Friday, November 21, 1997 9:21 PM
> Subject: Re: KV's and multimeters
>
> >
> >From: MATTHEW A PRICE[SMTP:ch038map-at-mode.lanl.k12.nm.us]
> >Sent: Friday, November 21, 1997 1:45 PM
> >To: Tesla List
> >Subject: RE: KV's and multimeters
> >
> >
> >>
> >> >From: MATTHEW A PRICE[SMTP:ch038map-at-mode.lanl.k12.nm.us]
> >> >Sent: Wednesday, November 19, 1997 10:47 AM
> >> >To: Tesla List
> >> >Subject: KV's and multimeters
> >> >
> >> >
> >> >Last night I finished the driver for the ignition coil useing a
> 555
> timer.
> >> >I was surprised when I hooked the thing up and it actually worked!
>
> >........voltage its putting out? My multimeter is a cheapie that only
>
> >goes up to
> >> >1000 V. Also why does it spark to everything..even when its not
> grounded?
> >> >
> >> >Matthew
> >> >
> >> >If you want to make better sparks, put in a variable resistor in
> the
> >> 555 circuit. Tune it until you get the longest spark. The best
> ignition
> >> coils are the red or blue ones. These are specially for use w/
> transistors.
> >> Also, TV transistors arent the best. IGBTs are the best, but simply
> a
> 3055
> >> is ok. My ignition coil throws 3/4 inch sparks easily. Or, if you
> want to
> >> make the longest and fattest sparks, use a thyristor in series with
> a 1uf
> >> cap and the primary. Feed this arrangement with 250 VDC. The cap
> charges
> up
> >> and discharges throught the primary. I used 350 VDC and a 4,7uf
> cap, that
> >> made 2 1/4 inch sparks!
> >> Atle Jorstad
> >
> >Help!!!! The driver that I was talking about is now giving me seriuos
>
> >problems. I replaced the TV transistor with a 3055 and the voltage
> was, as
> >you said, increased, but the thing quit working. After trying a few
> things
> >I decided to try a new 555, and it worked again, but quit again. I
> decided
> >not to fry anymore 555 (thats what I was doing, and the things don't
> grow
> >on trees!) so I wanted to ask you guys what I am doing wrong. Part of
> the
> >problem may be that I need a higher voltage rated wire, but I don't
> know.
> >The second time it only ran for a few seconds, and I didn't touch
> >anything... Please tell me what I am doing wrong
> >
> >Thanks
> >Matthew
> >
>
Have you considered power mosfets to drive the coil?I recently was
working in the 22kHz range with a 60 volt IFR510 N-Channel P mosfet in
an experiment to analyze optimum transformer frequencies. I hate 555's
so I used a 7414 (hex shmidt triggered inverter) and a 7473 (jk flip
flop) to make a 1:1 mark space output from my timer. I uses a 1k pot to
adjust the frequency from 50kHz to ~5kHz. I used the signal from the
flip flop to directly power the mosfet which drove two small 1:1
coupling transformers in series. -at- around 22kHz the transformers
developed there max potential around 130v which I used to charge up a
bank of caps. I'm sure those transformers could have been replaced with
an ignition coilor whatever. Let me know if any of this help.
--
____
/\/\ ((____)) /\/\/\/\ Joshua "Flux Boy" Resnick
/ | | \ \ http://www.wpi.edu/~seraphim
/ | | \/\/\ \ __ http://ece.wpi.edu/~seraphim
/ ____| |____ \
|||||||||||||| \ "Two parts oxygen and one part
lovin'."