Ballast manufacturing/design information

[Ria]

I've found the lamp out now, so will light it tomorrow and do some measurements. Heading to bed now, it's been a long day and we actually have to get up in the morning   to let the council sparky in to have a look at some work we need doing.

[Tuopeek]

If the currents right then you are likely to be all good with that ballast as it won't run as hot as mine. Will be interested to hear what the lamp voltage is when you measure it.

[Ria]

Thanks for the interesting post, Mark. We must be very lucky then, because the 50W SON ballast we use is pretty much spot on, certainly as far as lamp current goes, I don't recall the voltage, must get the lamp out and take some measurements, watch this space..!

[Tuopeek]

This is an interesting topic for me too. I have been looking at suitable ballasts for a 60W SLI/H linear sodium lamp I have and it's proving a little trickier than I first thought. That said, I have a 65W fluorescent choke which is pretty close. The only problem is the ballast gets very hot with time so isn't suited as an ideal alternative.  The popular choice of 50w SON is ok but not perfect. Everything else is way out.  I did look at a 70w fluorescent ballast but it behaves more like an 80w MBF/U mercury ballast so isn't suitable. However, it may be possible to wind a small inductor and add it in series to this ballast to bring it in line with the proper lamp current. This may be an option for the best outcome.  The issue seems to be, there are two properties of inductors that influence the circuit current other than the lamp resistance.  Ballasts also have a resistance plus reactance.  Measuring the reactance and basing choice on this doesn't work the coil resistance also needs to be taken into account and this forms an impedance problem (although not too tricky).  I need to look at a few ballasts and see if this proves fruitful in finding a different ballast for my 60W SLI/H. As for the 200W SLI/H I think the general choice is the 150W SON ballast but if I remember correctly, it actually needs a second paralleled ballast to achieve a better match. Can't remember the additional ballast, might be a 35w SOX but would have to look into that more. I'm lucky enough to have an auto-leak ballast for the 200W SLI/H but it's trickier to work out its impedance being technically a transformer. When testing the suitability of a circuit, I keep a close eye on lamp current and keep that as close to the design as possible. The voltage seems less important so long as its not higher than the spec. as this is where electrode damage occurs.

[Ria]

Heh. If you ever figure out how to make a ballast for a 200W SLI/H lamp, let me know, they are real unobtanium

[Bulbman256]

That's fine Ria, I'll keep on waiting till someone else chimes in. Mostly trying to recreate some American style F40T12 ballasts but I have plans to reverse engineer some other ballasts in the coming years. Eventually I may be able to custom make some ballasts for long forgotten lamps from scratch, but that will be when I am a much wiser man.

[Ria]

Hi Max,

No idea, I'm afraid, your namesake might be able to help, or Mark (Tuopeek), but other than that I'm absolutely no use (who said not surprising )

Take care,

Ria & Sammi 💖

[Bulbman256]

Hello everyone,

I was wondering if anyone had any documentation/information on how to properly design and wind FL/HID ballasts? This is a subject I've become increasingly interested in as the supply of these ballasts gets smaller and smaller each day. I've started doing a little research on my own but I can't seem to find anything beyond what the circuit diagram inside a ballast is. Another collector who is also interested in the same idea is sending me a few Rapid Start FL ballasts for study but any info helps.