Philips transistor ballasts

[Peter.N.]

I have a flush mounted 2X4' fluorescent fitting over my bench which I fitted when I built my workshop - many years ago. It has functioned perfectly until the other day when one tube wouldn't strike, I changed the starter then the tube - same problem, so concluded that the choke was u/s. I wanted to repair it if I could because of it being set in the ceiling.

I remembered some years ago purchasing a box of 24v Philips transistor ballast units very cheap in case I ever installed a wind turbine, that was a goodly number of years ago but recently I have installed one and have a good and tested emergency mains supply to power the house plus a permanant 24 volt supply. I had a rummage round and eventually found them in the loft of the garage.

There were two types, one for a 2' 20w tube and most of them for 2X30w 3' tubes so I hooked them up one of my 4' tubes and lo and behold there was light, its not as bright as when on the mains but bright enough with both tubes on, the current consumption is just about 1 amp on each tube, or 24 - 30 watts, I reckon that is efficient.

The thing that surprised me most was the enclosed piece of paper with the installation information - dated 1973! and so far they all work.

Peter

[Lucien Nunes]

I have a couple of the 12V versions also new in box. I was going to use them on the boat but decided, like most of my NIB stuff, to keep them as-is. During testing, ISTR the power input was slightly shy of nominal rating but most low-voltage DC input transistor tube inverters are like this. I have yet to find one that genuinely pumps the same mean current through a tube as a correctly rated wirewound ballast.

I later changed all the fluorescents on the boat to low-profile fittings using a total of 34 12" 8W tubes. Can't remember the total current but it is definitely less than 22A at 12V.

Lucien

[Peter.N.]

Hi Lucien

The 2 X 30w ones which I am using are rated at 1.9 amps but are only drawing just under an amp when cold and just over when warm, I thought they would have taken more than that as the internal resistance of a 4' tube would have been less than 2 X 3' but not so, I tried another one in case the power was down after all these years and that was the same. The capacitors are obviously still good, not only do the units function but you get a nice 'crack' when you connect them up.

Peter

[Lucien Nunes]

Are the 3' tubes intended to be in series? I can't remember whether the Philips ballast drives the heaters or relies on emission heating like many of the modern inverters, in which case presumably it has three heater windings?

I wonder who made the first electronic fluorescent inverter? Labcraft have been in that market for a long time but there might have been others looking for something to do with a pair of OC28s or AD149s.

Lucien

[Cobaltblue]

There were designs in the Magazines in the 60s for florescent inverters I made one around 1969. I think that one I built used AD161's and I am sure they were around before that. I had a summer job with a small engineering company (Liskeard Engineering) in 1972 and they were making emergency lighting using a little inverter but I am sure that used a single BD131. The emergency lighting unit I am pretty certain was made for a company called BBI. It had 2 8" tubes. So my expectation is that Electronic ballast has been around since the first power transistors.

[Peter.N.]

I remember those early transistor ballasts, or more particularly the 6" or 9" fittings made for caravans, I think the ballasts started being made pretty well as soon as there were suitable transistors.

Lucien

Yes the 3' tubes are shown in series, the circuit is actually on the ballast unit, it does have heater supplies including one for the center of the two tubes in series, but it starts up quite well without them - or at least it did when I did as I was told and connected one side of one heater winding to the metal fitting, wouldn't strike at all without that!

Peter

[broadgage]

There was, and probably still is, "the worlds first transistorised flourescent hand lamp" on display in the Science Museum, London.
About 1969 I think.
This used an HP 1 battery, a 12 volt zinc carbon battery with a socket on the top, looked a bit like an HT dry battery.
The lamp was 9 inch, 6 watt.
Starting was manual with a three position switch for off/start/run.


Transistorised flourescent lamp circuits for battery operation certainly existed in the 1970s power cuts, but were not yet in general use.
Emergency lighting of public buildings was normally by low voltage GLS lamps powered from a central battery, flourescent fittings existed but were not the norm.
Portable lighting was largely torches with zinc carbon batteries and incandescent bulbs. If a brighter light was needed, handlamps with a lead acid battery and bulb of 20 watts or more existed, but were costly items.
Parrafin portable lamps were in widespread use, being much cheaper to buy and cheaper to run than the rare and costly battery flourescent lamps.

[Peter.N.]

I still have one of those 6 volt farmers lamps with a motorcycle headlamp unit, two switches for main beam or pilot and a lead acid battery, its a heavy old thing but you can't beat it for a long distance beam.

Peter