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Re: KV's and multimeters
From: Antonio Carlos M. de Queiroz[SMTP:acmq-at-compuland-dot-com.br]
Sent: Saturday, November 22, 1997 12:54 PM
To: Tesla List
Subject: Re: KV's and multimeters
Matthew wrote:
> 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.
You must use a high-voltage transistor. The 3055 supports only about 70 V
before the base-collector junction breaks. And your 555 is there (with a
resistor between pin 3 and the transistor base?). After a more intense
breakdown, or a series of them, due to the high voltage pulse that appears
at the collector when the transistor interrupts the current at the primary
of the coil, the transistor, the 555, or both, are destroyed.
Some possibilities:
Return to the high-voltage TV transistor.
Connect a small neon lamp in parallel with the primary (it will clamp the
HV pulse).
Use heavier wire for the ground connections. You may be destroying the
555 with high voltage pulses coupled through the ground lines.
--
Antonio Carlos M. de Queiroz
http://www.coe.ufrj.br/~acmq