the LANGUAGE of electronics, a minor rant

[on1aag]

The hammock.

Hi Hero999,

Regarding the hammock; I only knew it was a fluorescent tube because I've seen the circuit before. The diodes and electrolytic capacitors form a half wave voltage quadrupler which generates a 1.3kV spike which ignites the tube. Once the tube has been lit the non-polarised capacitors act as a ballast and power the tube as normal.

There's no voltage or frequency on the power supply so I assume the circuit runs of 230AC as the electrolytics are rated for 350V.

The ballast capacitors aren't labled there are no component designators.

Unless you only want to dimly light a tube this circuit isn't very practical as to even light a 4W tube at full brightness the ballast capacitors will need to be 5:mu:F which is quite a large at they'll need to be rated at 120VAC.

You could only have seen this circuit on Edaboard, that's the only place
I uploaded it. Your explanation is ok except for one minor detail:
It doesn't work !
The tube ignites three to four times each half period but it doesn't
stay on. I increased the current through the tube until it got purple
but it still wouldn't stay on.
However there's a way to make it work: Connect the ballast of the tube
in series with the circuit and use two bipolar capacitors with the
double value of the supplied tg :delta: capacitor. But you gonna have to
connect five fat 2,2 µF 250 vac / 1000 vdc capacitors in parallel to
get the required 11 µF. (The leakage current of the large aluminium
cans is far too big to get them charged up to 650 volt.) And . . .
you need two of those capacitor banks because they are connected in
series for the ac current through the tube.
And that's where I left it, I wanted to design a circuit without the
ballast and I ended up with a circuit with the same #$&%*& ballast in it.
I think it is also possible to replace the ballast with a resistor but
that circuit will have even more losses.
If someone thinks he can get it to work without the ballast . . .

on1aag.

 

[Hero999]

I didn't know that fluorscents go purple when the current gets too high, I suppose that might be because some of the argon is ionising.

What sisze tube did you use?

You probably won't have any problems with 4W or even 8W tubes, I've even managed to get a new 4W tube to ignite at the normal mains voltage without using the heaters.

However, if you're trying to power a larger tube like 22W then forget it.

 

[on1aag]

Hi Hero999,

What sisze tube did you use?

You probably won't have any problems with 4W or even 8W tubes, I've even managed to get a new 4W tube to ignite at the normal mains voltage without using the heaters.

Good question, that was at least twenty years ago. I think a Philips
TLD 15/33, 15 watts, and also a Philips 15 watts ultraviolet tube,
same dimensions but transparent, possibly also a 36 watts regular
version too. I don't think I tried 4w or 8w versions because I can't
find any.

on1aag.

 

[crusty]

all the pros free hand it in mspaint, cuz were pr0z.

 

[audioguru]

I don't use a free hand in MS Paint. I draw straight lines by holing down the shift key.
I don't "draw" anything. I usually copy parts then paste them into my new sketch.

 

[Hero999]

Hi Hero999,



Good question, that was at least twenty years ago. I think a Philips
TLD 15/33, 15 watts, and also a Philips 15 watts ultraviolet tube,
same dimensions but transparent, possibly also a 36 watts regular
version too. I don't think I tried 4w or 8w versions because I can't
find any.

on1aag.

That sounds like a germicidal tube, why didi you want it? To erase some EPROMS?

It's probably good it didn't work or you may have damaged your eyes or got severe sunburn.