[Prev][Next][Index][Thread]
Re: KV's and multimeters
From: Mike Haydon[SMTP:haydons-at-capstonebank-dot-com]
Sent: Friday, November 21, 1997 9:22 PM
To: Tesla List
Subject: Re: KV's and multimeters
At 10:34 PM 11/21/97 -0600, you wrote:
>
>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
>
>
>
Matthew;
I do not know your exact circuit setup, but suggest you may be asking the
555 to sink too much current. I don't know the exact gain of a 3055, but
beleive it to be rather low, and since base current =Collector current/ Beta
(transistor gain), It may well exceed the 100mA a 555 is rated at sinking.
Would an emitter follower buffer stage work in your circuit??? Just a
suggestion.
Good Luck!
Mike, KF8ZN (Ham callsign,
not a Yiddish Curseword)