LF / HF fluorescent fittings - how to spot?

[Jim K]

How do I tell if some fluorescent tube fittings I have acquired are HF or LF?

ta Jim K

[sm_jamieson]

1. Look at the ballast - there should be some writing on it.
2. A LF magnetic ballast will be quite heavy (like a transformer)
3. A LF magnetic ballast will have a starter or a socket for a starter (may not be visible externally), and probably a capacitor.
4. If you power one up if will flicker at 100Hz - some people can detect this, although about 85Hz used to be enough to stop flicker on a CRT. Spin something at 100Hz or multiples, and it will appear stationary.
5. A HF ballast may cause RF interference on nearly radios etc, especially if the earthed cover is removed.

Note: it could be a purely capacitive ballast, which will not be heavy, but those are rare, except pair with inductive in lead/lag pairs in industrial settings, in order to mitigate the stroboscopic effect.

Simon.

[Brian Gaff]

Yes I had one of those double fittings that went into a normal bayonet socket, very light, just it appears a small cap in the system, nothing wlse. Only problem was on cold mornings the things just would not start!

I think the rotating idea is a good one for detecting flicker, though I recently found a little light detector from RNIB that buzzes in daylight or any constand light, but gurgles on flickering ones, I guess one might call it an audio interference pattern!

I agree about the issue with RFI, though some of the choke ones can give of some nasty rasping noises if the tube is a bit low. Brian

[Fredxx]

If you look at one of the tube ends out of the corner of your eye, flicker should be evident if using an LF ballast.

Also running an open hand (ie with separated fingers) across the view of the tube, you should also see a stroboscopic effect.

[meow2222]

Move your eyes as fast as near instantly as possible across the tube, LF ballasts will leaves visible lines on vision, hf will just smear.

NT

[Andrew Gabriel]

ballasts will leaves visible lines on vision, hf will just smear.

If you have a hand-lamp with a fluorescent lamp with a LF balance, an interesting effect can be seen by whirling it around above your head. Besides the stroboscopic effect, you can see the persistence of each of the phosphors.

Of course, if you whack it on something in the process, a different and altogether less satisfying effect results...

[The Natural Philosopher]

ballasts will leaves visible lines on vision, hf will just smear.

altogether more, shirley?