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What to do with a tube from a CFL that has broken electronics? Answered

I have a couple of broken CFL's, The tube still works and I want to do something with it.
Any ideas on how to make it light up from 12 volt, Without a ionization antenna (Using the heating filaments instead).

Any other ideas??

Anyone else want to know what to do with them too?

I don't want any comments that say THROW IT OUT or similar


the push pull setup is allmost the standard setup copied and mirrored

there is small difference with the way the transistor bases are connected to prevent it from freezing in the who starts first question (the transistors are identical)

usually a one transistor can perform well and is more tolerant to badly matched components etc. i suggest to start with 1 and see if you need 2 at all


That seems like a pretty good setup, I'll try that as soon as I get my parts back, What size resistor should I use? How many turns in that extra coil?

resistor is few k ohm or less and depends on the transistors you use the extra turns depend on lots of stuff too search online for exact circuit or just experiment









yep but if you look after the diodes there are 3 wires going to the circuit. they are like 2 dc supplies one at full voltage and one at half (the center wire)

the capacitors are not necessarily polarized. they draw them all with curved line. see the one at the right which is on ac and cannot be polarized

and with second thought . . . this circuit needs external high voltage source or heavy modifications to work on 12 V there is no transformer in it. in no way it can make more than 24 V out of 12 V. the chip works with 12 V but its not enough for the lamp

There's a couple of inductors in there that I presume are used for obtaining a high voltage.

It says that the Vb pin can reach 625 volts, Enough to keep the tube lit. I don't know how it reaches it though

Have a look at page 23 of the datasheet, It tells you the parts and it says that the line voltage was 110VAC??!!?!?!?!?!


it runs the lamp and the preheat from line voltage (both thru appropriate resistance)

with 12 V it is ossible to drive the chip and preheat but not make discharge. adding step up transformer may be possible but is complex. its simpler to make something without this chip than to hack the circuit to work on 12 V

on 12 V preheat and discharge work better when preheat is directly from DC and discharge is from inverter. in standard high voltage systems they both are done from the same supply

here are some shots of magnetic perfektstart ballasts for 240 V. they are made of transformer and thermal relay. in 12 V the transformer is replaced with inverter and thermal relay with standard relays and timing circuit

(lol in the old one (larger one) they actually wrote perfektstart with K)


Cool, What keeps the relays from closing the circuit for the filaments?

in the device in the image the thermal relay heating element is connected to a secondary coil added to the ballast. to simplify things imagine that its just wired in series with the lamp (it'd work the same way) the relay is closed by default when you switch on power current passes thru the closed relay and the filaments. the relay's heating element is in series with everything and the current goes thru it too and heats it after 1 - 2 sec the relay is hot and opens - switching to the normal work mode the current of the working lamp is lower but is still enough to keep the relay warm so it'll not close. this condition remains all the time the lamp works if lamp did not strike successfully on the 1st attempt or it drops out then it takes no current. the relay cools down and closes and the startup begins over (with bad lamp it'll try again forever) a thermal relay is used cause its responses are slow and give the filaments sufficient time to warm up in electronic edition we need to do the same things ourselfes. basically this means some circuit that senses current thru the lamp and a delay circuit. they are connected to the start wires in the circuit i showed before if its ok to make it less reliable then it can be made way more simple - the start signal is just connected to the supply thru a big capacitor. it takes the capacitor a second or two to charge thru the relays. when its complete it takes no more current and the relays open. the problem is that if it fails to start on the 1st attempt it won't try again (untill you switch it off and on yourself)

Ohhh. How big of a cap do you think I should use? I have a couple of 1000uF electrolytic caps that I could use. I thought we could use a bleed resistor to discharge the cap for the relay, but that would let voltage pass through itself, Having a diode would solve that problem though.

it very depends on the relays. try until you get the correct timing (1 - 2 sec) with capacitor its better to connect only one relay to it and the others thru the 1st one. this way you ensure that all the relays react at the same time the switched off circuit itself (which includes the inverter for the high voltage) usually is good enough bleed resistor. if not then add one in parallel with the 12 V

most of those inverters can strike the lamp without the help of filaments the filaments are needed to make it start more reliably in cold environment (like outdoors in winter) and make it live longer (cool starts kill the electrodes quite fast and make the ends of the lamp become black) the capacitor way ensures that the filaments are warmed up. if the inverter can start the lamp on its own it'll sure be able to start it with help of filaments (after the relays shut down the filaments they are still hot enough for a split second. if we count each half wave the inverter makes as a strike attempt then it makes lots of them in that time before the filaments cool down) the capacitor way is not reliable if the invertor cannot strike the lamp without warm up. in this case a single warm up may not be enough and it should be built to retry more times

For the inverter, Can I put 12 volts into a astable multivibrator and the output of that through two transistors, changing 12vdc to 12vac then have that going through a transformer?

I have started building the perfekt-start circuit.

To put that into simpler terms, have a look at the schematic (sorry, didn't have time to put values on the resistors and caps)


it can be made simpler. the transformer itself can replace some parts in the multvibrator circuit the following circuit is a low power high voltage capacitor charger if you scale it up a bit and put larger transistor you can make it give good watts out the secondary of the transformer goes to the cfl directly (without diodes)


the output voltage of xformer depends on change in the input voltage and not the input voltage itself this way the xformer outputs positive voltage when the dc input rises and real negative voltage when the dc input falls (from +something to 0)

Oh, Really, So you don't have to put AC into the xformer for it to output AC?

you dont have to some inverters use 2 pulsed dc supplies which work in push - pull and are connected to 2 opposite direction windings this sometimes improves performance but does not change the type of current on the output. its same as with 1 transistor

Something like this, I hope you don't mind that I modified your schematic..... You just have to orient the diode to the polarity of the battery.........


there is no need in a diode usually it bleeds thru the relays and into the switched off circuit so no need in resistor. if no then add resistor (with value high enough to not take much current all the time) in parallel with the 12 V supply (after the switch) nothing is connected in parallel with the capacitor important - the high voltage is supplied from a limited power source (inverter powered from the same 12 V). do not connect to ac mains !

they seem more like stabilizers they aint gonna use joule thief in a cfl. its inappropriate for the amount of power

Yeah, I guess so, It says on page 23 of the datasheet that that diagram was for running a 42 watt lamp at 110 VAC ;-(

Yeah, The center wire is just the neg. or pos. input, the other two are the same wire...

Have a look on this page, Where the symbols are, it tells you which ones are polarised and which ones aren't.

Which cap are you talking about when you say see the one at the right what component number/letter is it?

they (irf) draw all of them with the polarized cap symbol you can tell if its polarized by looking what the cap is connected to or from the parts list for example the one on the right (between L and N) is sure not polarized cause it gets 110 V AC

Smash it, of course! Grrrrr, I don't want to die yet

Find a nice transformer and try to light it up from placing it around it.?? Induction?

Already taken apart..

And the transformer doesn't work. ;-(

Yes, induction

That comment was more to annoy you and break you rule more than anything else...

I didn't think induction would work.....

I knew there would be someone (you) who would break my rule thing.....

Ohhh, Cool, I can't download it now or risk going over my grandparents broadband allowance ......

I mean it! It's only 1000mb download limit, at about 700mb now....