Help with Jaycar kit

[stoj]

Hi all
I was wondering has any built a Jacobs ladder high voltage display kit form
Jaycar (cat number KC5191).
I am asking this because I recently purchased one and put it all together
and when I went to try it out nothing happens. I have checked all the
components and they all seem to be ok, I have also used 3 different ignition
coils and still no spark is produced only when the power is disconnected. If
any one has any advice in where the problem is their information is greatly
appreciated.

Thanks in advance.

 

[Pippa]

On Fri, 23 Jul 2004 11:42:37 +0000, stoj wrote:

Hi all
I was wondering has any built a Jacobs ladder high voltage display kit form
Jaycar (cat number KC5191).
I am asking this because I recently purchased one and put it all together
and when I went to try it out nothing happens. I have checked all the
components and they all seem to be ok, I have also used 3 different ignition
coils and still no spark is produced only when the power is disconnected. If
any one has any advice in where the problem is their information is greatly
appreciated.

Thanks in advance.

Try replacing the pair of 'ladder' wires with a spark plug. Make sure you
connect the body of the spark plug to the negative connection on the coil
so it is able to form a complete circuit.

You should get a continuous spark sequence jumping across the plug gap.

If this works you probably have the gap at the bottom of the ladder too
wide for the initial spark to jump across. From memory when I built one of
these things years ago, I had to set the gap at the bottom of the ladder
to about 2 mm for the spark to be able to form.... any wider and the
voltage generated by the coil was not sufficient to ionise the air.

From the description you have given of the unit producing a spark only
when powering it down, it could be too wider gap at the bottom of the
ladder, you get a higher voltage spike when powering the unit down than
when it's running.

OR it could be that the oscillator is not running.... you would then just
have DC flowing through the coil primary. A quick check of the FET driving
the coil using an ohm meter should find if it's gone short circuit.


Have fun!


Pip

 

[Ross]

In article <NQ6Mc.12832$K53.4986@news-server.bigpond.net.au>, stoj wrote:

Hi all
I was wondering has any built a Jacobs ladder high voltage display kit form
Jaycar (cat number KC5191).

It's most likely the 555 timer. The kit notes expressly say that a cmos 555
is unsuitable but that's what Jaycar sells so that's what they put in the kit
(or they did when I got one years ago).

--
Ross
(remove Chaff to reply)