Australia's Science Forum

Hi,
We have fairly new spectrum tubes (set of 6 in a stand from IEC) and a new high voltage induction coil. When we fire them up they run for a few seconds then stop. Not long enough to observe the colour spectrum. Any ideas or tips?
Thanks

Annette , care to throw up a picture of the induction coil and even the tubes

Not sure if I have attached the photo correctly.
This is our set up. I have found that by adjusting the screw it goes on and off but I cannot get a consistent connection/flow? We have a new induction coil (in the background) that seems to be even worse. Should I get one of those spectrum tube power supplies that does not require an induction coil?

We use an IEC EHV 0-6000V power supply which works. Can also be used for cathode ray tubes, Maltese Cross, paddle wheel etc. It's worth investing in for ease of use.

ok thank you. That does look a lot easier to use.

I got one of these power supplies for ours .

viewtopic.php?p=48804#p48804

I was looking at your holder and it reminded me . We got one of those in our set of tubes from serrata ( MTA) .

Teacher whinged that all the tubes were glowing . She was kinda right . If the probe was connected to a tube , the ones either side would flicker with a faint glow .
So we ended up getting out our old single tube holder and using them one at a time .

Not saying that has anything to do with your issue just to be aware of .

The 6kv power supply is a great idea . Especially if you can run all the crooks tubes on it as well .

However the curiosity of why your induction coil isn’t working is too much for me LOL .

If you just use it on it’s own , but with the spark gaps connected , does it continue to run evenly while producing a spark ?
A nice spark gap of about 10-15mm should be plenty to run the tubes.

We found one of our induction could wouldn’t run nicely unless it was producing a spark .It is actually bad to run an induction coil without a spark gap because if there is no deliberate place for the voltage to break down , it can do it internally in the coil and damage it causing tracking paths .

You can run the tubes in parallel with the spark gaps.

Another of our old induction coils had a faulty Capacitor . It was mounted underneath the wooden base plate . Cost about $2.50 for a new one .

Oh wow thank you that is a great help. I had a more experienced bio teacher walk in this morning and start playing with it. He seemed to be able to keep it going better but you have to continually tweak the screw. Maybe I need to sandpaper the connections a bit.

The induction coil does produce a good spark when run on its own.

Just one more question to clarify, so it is better to run it with the spark going while connected to the spectrum tubes?

Yes I would always recommend having a spark gap set to the widest setting where it will still arc consistently while using anything connected to an induction coil . If the device connected requires less voltage then the spark will stop . That is OK .

Ok will do. Thanks for the help.