"SBS" schreef in bericht news:45c72973$0$31670$ email@example.com...
Guess so. I build one and it works fine. A friend of mine has an inpection light with similar circuit. Worked fine as well untill it fell too hard one time. (This broke the tube and the enclosure, not the electronics. I checked it out by myself.) Some say the lifetime of the tube will decrease. Maybe true, but I've had no problems so far. The only drawback is some more flicker compared to a conventional ballast, so it may not be a succes as a reading lamp. I also experimented with the electronics of a worn out electricity-saving lamp. A 8W tube works really fine on the electronics of such a 9W lamp. If you google around, you will also find some sites dealing with this things.
This circuit looks like a typical 'play around with lots of components but ensure you do not know anything about what you are doing' type circuit. On 220V ac a single series cap will work as a ballast. Since many (but not all) 8W T5 tubes's, at room temp, will begin to arc as low as 250V
- that is all that is needed.
With a capacitive ballast the crest factor is appalling, the cathodes will be stripped etc, life and output reduced. That is why it is not used.
Why do you need an 'electronic' ballast? What is the advantage of an electronic ballast in your application - size, thermals,..... ??
RHRRC ( firstname.lastname@example.org) ha scritto:
:: Why do you need an 'electronic' ballast? :: What is the advantage of an electronic ballast in your :: application - size, thermals,..... ??
I need an electronic ballast because I want to reduce size and weight of the resulting device I am building.
Petrus suggested me to use the electronics of an energy saving lamp with about same power consumption of the fluorescent tube I have to use. Other experience with electronic ballast from energy saving lamp?
"RHRRC" schreef in bericht news: email@example.com...
Well, I neither designed nor analysed the circuit but if you want to...
A lot of circuits of commercial available electricity-saving lamps can be found on:
That guy Pavouk dissected a lot of them.
I myself use the electronics of a 20W electricity-saving lamp to drive a circline 22W tube. Even works with some older tubes that did not start on the original - classic - ballast anymore. (Which was the main reason to drop the old ballast. Tubes became useless much too fast.)
You can buy an electronic ballast as well. Conrad for example sells them:
Been running a normal 8W tube off a ballast from a 9W lamp on our boat for the last year. Must have close to 500 hours running time now with no problems whatsoever. Its far cheaper than you can build it, even buying a decent quality energy saving lamp new.
As Paul has stated, all 8-watt fluorescent lamps do not have the same electrical characteristics. I suspect you have an
8-watt T5 lamp, which has a diameter of 5/8 inch and a length (end of pin to end of pin) of about 12 inches, but you may have another lamp with different electrical characteristics.
Your inability to "find" a suitable transformer is not unusual. Most ballasts I am aware of use custom transformers. The reason for this is that electronic ballasts do not operate at a standard frequency and they run a great variety of lamp loads. So, usually a standard ferrite core is used, but the number of windings and the number of turns on each winding, are customized for each application.
There are also many designs that use only a series inductor, which is easier to design and build than a transformer.
You can find designs that use standard magnetics at
but I don't see any for any 8-watt lamps (but then again, I didn't look very hard.)