Big Joule Theif

[rave154]

thanks

Thanks for the replies guys,

a bit of a an electronics newbie here, so all help appreciated,

i was just drawn to wanting to recreate slayers high voltage theif circuit when i saw his voltage go over 1000 in the vid, am a bit of a voltage hound as well as a newb ( dont worry, i take ALL precautions ! ).

[David_Cooksey]

Winding Big Toroids

Is there a simple way to wind large TOROIDS where you have
100+ winds on them.

David

[slayer007]

Is there a simple way to wind large TOROIDS where you have
100+ winds on them.

David

Yes David

Wind your wire on a long thin bolt.
Wind two strands on the bolt for the JT part.

Then feed it throught your toriod(kinda like sowing).
Then do the same for the pickup coil but only one strand of wire on the bolt for the pickup coil.

[shubhamforme]

@Xenomorph

Well first of all the charging part can be HV (not as High as the Neon side). With my 90 turn coil I got 500V voltage spikes. I have not scoped this coil yet but its definitely enough to light a neon so we know its more than 90V.

My idea is to have a relay switching between:
1. lighting the Big Fluoro off the secondary coil
2. charging a cap off the Collector

We do this fast enough so that we do not notice the pulses in the light. Its hard to charge a light the Fluoro at the same time so why dont we do one when the other is off.

It removes the 555 from the front and puts it to the back. The JT will have full on time but im sure we could get better charging out of it.

Check out the attachment, I drew up a circuit. I was just about to try it today... I had the 555 built, got the relay switching, then it died on me!! Damn!
-shlodo

hi there!!
i liked this idea of yours ,, even i ws trying to come up with something like this....but was unsuccessful...maybe you can try that..??
can you past a circuit of this design?
thx

[Watson]

Pulse Inverted Joule Thief Circuit Schematic

Hi guys i did a updated drawing of Slayer007 drawing
of the Pulse Inverted Joule Thief Circuit

One thing that is very important is the 0.1 uF bypass capacitor across the power supply pins of the 555. Leaving this out can cause weird and unpredictable 555 operation, like spikes in the output. Read the 555 datasheet to find out why. Also the overall circuit should have a good size bypass capacitor at the power supply input pins. A good starting value is 1000 uF for each amp current. Like 470 uF for 1/2A, or 220 uF for 1/4A, but more doesn't hurt. Again,this is necessary for good stability.

The.0047 at winding B2 seems a bit too small, too.

[Watson]

UPDATE - LEDs Have Air Bubbles In Lens

Wish it ends well -- keep us updated about the ebay story.

After a week or so Paypal made a decision in my favor, so I logged on to PP and found $30 credited to my account.

I found this Chinese Co. that sells cheap LEDs for throwies, but you have ro buy a lot of them. Click on fhe x-type box. Most other types, too.

Power LEDs

[Watson]

Thanks for the explanations. It is fascinating. I will study your circuit more closely when I got some time.

For those who are interested, I'd like to give an explanation of JT here:

Let's start with the point of time where there is ZERO collector-emitter current in the 2n3055. Now because of the battery, there will be base-emitter current through the trigger coil, limited by the resister in series. This makes the transistor close (as a switch) between collector and emitter, but keep in mind that there is a ceiling cap on the current that can flow through (roughly equals the base-emitter current multiplied by the beta parameter of the transistor). So current in the power coil starts to increase, until the current ceiling cap is reached, at which point the current stops increasing. Mind you one more crucial detail: while the current was increasing in the power coil, the trigger coil can pick up a little boost and that help contribute to the base-emitter current. Now when the current in the power coil stops increasing, such a boost ceases to exist and this immediately drops the ceiling cap quite a bit (say, 20%, depending on how much boost the trigger coil picks up from the power coil). Such a drop of ceiling cap sends the power coil into its down turn at once -- the current in it starts to decrease, and such a current decrease in the power coil further lower the cap through the pick up (inductance) at the trigger coil ( in fact, the decrease is usually fast enough to shut off the transistor completely). The decrease stops until the current in the power coil reaches ZERO, and we are about to start a new cycle. That's it, folks!

In the above he talks about the current being limited by the transistor's beta (hFE in the datasheet). The beta or current gain is curcial to getting enough current through the transistor to power the output (LED in a JT). Conventional transistors including the 2N3055 don't have good beta holdup at low collector voltages, the beta drops off when the collector voltage is low. We need a special transistor that has very high beta at very low collector voltages. And it also needs to have very low saturation voltage at very high current.

If you look at the transistor on the flash unit from a disposable camera, you might think, how could that tiny transistor be drawing over an amp from the AA cell when it's charging? but it can and does! In fact that transistor can handle up to 5 amps!! That's 10 to 50 times the current of a conventional 2N3904 or 2N4401 (same as the PN2222).

So what are t hese super beta, low Vce(sat) transistors? Some commonly found ones are the 2SD965 AKA FJN965 from Fairchild, or the KSD5041 also from Fairchild, available from Mouser.com for $6.60 per hundred, which is 16 times cheaper than the 2N3055, at a buck each. You could burn out a dozen of these and it'd still be cheaper than burning out a single 2N3055. And the good part is that a single KSD5041 will crank out more power than a 2N3055 in a conventional 1.5V Joule Thief circuit.

You don't believe it? Try it sometime, and you'll be a believer. You could put a dozen of these in parallel and drive a high current JT to light up a 1W or 3W Luxeon Star. I've put 5 of them in parallel to drive a Luxeon 1W to over a hundred mA. But my problem is that the 1.5V power supply maxes out at 1A, so I gotta beef up my PS. Maybe I should try a couple D cells in parallel? Whatever..

[teslaproject]

MPP and a million other little things

@ Guruji

Running at 3v with two 1.5v batterys.

The rectified voltage across the sedondary going into a small capacitor is around 380 volts.

It should take close to 300v to run a CFL.

This was tried with the basic JT circuit with only one transistor.

One thing you could also try is to take out the 1k resistor and put a 5k pot in it's place.
That way you can go below 1k if you need to for tunning.

Also for best results the toroid should be a ferrite toroid.

P.S. I used a rectifier across the secondary because the AC comming off the secondary isn't true AC it might not be right at 60mhz.
So my meter wouldnt read it correctly.

Slayer!! where art thou?

Really fantastic input on the thread (also Lidmotor)...therefore thanks. Couple queries whether some clever people might be able to help me out.

Firstly, Slayer you mentioned that ferrite toroids have given you the best result. Whats the heaviest current and voltage you have run through the big coil (Im actually having trouble keeping up which version you are up to ) and is your ferrite generating considerable heat? I was thinking of giving MPP cores a go. What do you think?

Have you (or anyone else here) attempted a bifilar/quad/single/other wound 'standard' coil but make either the primary/pickup (or both) 'directional', rather than laying the magnet wire back and forth in a standard overlay?

I was wondering whether you came up with a good idea other than mechanical (I'm trying to stick to 'solid state') for high speed switching. I'm attempting a number of things but seem to keep burning out my transistors or 555 circuits on the longer term 'heavy duty' voltage tests. Too much power perhaps
Either way, I would love something more robust than these heat prone bits of silicon.

IF I wanted to protect the circuit from a either spikes/surges and keep the voltage steady at one level when the 'input' might typically be ranging beyond the realms of a standard resistor, whats a more dynamic buffer I could place on the front end? I was toying with the idea of MOV's but they will be no good in the long run because they have a limited lifespan.

Thanks again.

TP

[lanenal]

After a week or so Paypal made a decision in my favor, so I logged on to PP and found $30 credited to my account.

I found this Chinese Co. that sells cheap LEDs for throwies, but you have ro buy a lot of them. Click on fhe x-type box. Most other types, too.

Power LEDs

So it ends well -- at least not bad .

[Watson]

"beyond the realms of a standard resistor"

Slayer!! where art thou?

[snip]

I was wondering whether you came up with a good idea other than mechanical (I'm trying to stick to 'solid state') for high speed switching. I'm attempting a number of things but seem to keep burning out my transistors or 555 circuits on the longer term 'heavy duty' voltage tests. Too much power perhaps
Either way, I would love something more robust than these heat prone bits of silicon.

IF I wanted to protect the circuit from a either spikes/surges and keep the voltage steady at one level when the 'input' might typically be ranging beyond the realms of a standard resistor, whats a more dynamic buffer I could place on the front end? I was toying with the idea of MOV's but they will be no good in the long run because they have a limited lifespan.

Thanks again.

TP

I use some high speed rectifier diodes I got from a PC power supply to clamp the outputs to the power supply + and -. For instance, a 555 should have a HS diode from pin 3 to ground, cathode to pin 3, and another from pin 3 to +, cathode to +. If the pin 3 voltage goes 0.6V higher or lower than the + or -, the diode conducts and clamps it.

The base of the power transistor should have a HS diode from base to emitter, cathode to base. This prevents the base from going negative in relation to the emitter.

If the voltages at the collector of the power transistor are going to be high, then it should not be a 2N3055. Use a horizontal output transistor that can handle several hundred volts. Or else clamp the 2N3055 with zener diodes so that it can't et higher than 60 volts.

This type of thing where a power transistor has to handle high voltage and current is known as SOA, safe operating area. The datasheet shows where the limits are. Exceeding these limits usually lets the smoke out.

For many years, you have turned on your TV set and watched a picture that was made by 30 thousand volts on a CRT tube. This was generated by a flyback switched by a power transistor. There is no secret to doing it right. Just don't do it wrong.

Also it is mandatory that the 555 have a 0.1uF bypass cap across the power pins, close as possible to the chip. There is a high current during switching and this cap is needed to filter it out. If this isn't taken care of, the 555 output can do some rather strange things.

The term "beyond the realms of a standard resistor" that I saw above is not science, it's science fiction. Your resistor is a resistance, and has a maximum power limit, which has to be observed. There's no magic to that.

It's not that the silicon isn't robust, it's that the circuit is subjecting the silicon to voltages and currents outside its maximum limits. If you need twice as much current through a transistor, perhaps you should be using two transistors in parallel, to split the current between them.

If you can't tame your circuit, I've got a box of 100 2N3055s here that I could sell to you for maybe $50, that should take care of your power transistor needs for awhile.

[teslaproject]

@Watson

Thanks Watson for the informative reply.

I had to chuckle at your 'science fiction' comment regarding my resistance desires. Perhaps I hadnt worded it correctly and therefore deserved a good clip behind the ear.

Anyway, thanks again, some excellent suggestions regarding 'precautions' I obviously havent been implementing. I might take you up on that transistor offer also.

Kindest

TP

[morpher44]

ignition coil or flyback?

So the "big joule thief" is using 2n3055.
Question: Anyone try using an IGNITION coil or
flyback coil?
I guess one problem with ignition is that NEGATIVE is common
for primary and secondary and joule-thief is not happy with
that arrangement.
A flyback, on the other hand, might work -- especially if it doesn't
have a diode on the high-voltage lead -- like some of them do.

-- morpher44

[slayer007]

Slayer!! where art thou?

Really fantastic input on the thread (also Lidmotor)...therefore thanks. Couple queries whether some clever people might be able to help me out.

Firstly, Slayer you mentioned that ferrite toroids have given you the best result. Whats the heaviest current and voltage you have run through the big coil (Im actually having trouble keeping up which version you are up to ) and is your ferrite generating considerable heat? I was thinking of giving MPP cores a go. What do you think?

Have you (or anyone else here) attempted a bifilar/quad/single/other wound 'standard' coil but make either the primary/pickup (or both) 'directional', rather than laying the magnet wire back and forth in a standard overlay?

I was wondering whether you came up with a good idea other than mechanical (I'm trying to stick to 'solid state') for high speed switching. I'm attempting a number of things but seem to keep burning out my transistors or 555 circuits on the longer term 'heavy duty' voltage tests. Too much power perhaps
Either way, I would love something more robust than these heat prone bits of silicon.

IF I wanted to protect the circuit from a either spikes/surges and keep the voltage steady at one level when the 'input' might typically be ranging beyond the realms of a standard resistor, whats a more dynamic buffer I could place on the front end? I was toying with the idea of MOV's but they will be no good in the long run because they have a limited lifespan.

Thanks again.

TP

Sorry teslaproject I didn't see your post till now.

The most voltage I sent through the ferrite toroid JT was 12 v the most current was close to around 1 amp.

It didn't seem to run much better with the higher voltage and current.
At least with the coil I was using.

The ferrite toride does not get hot at all even at 12v.

For the best results or preformance I was using two or three 1.5v AA batterys.

[teslaproject]

@ Slayer

Thanks for the reply Slayer, I appreciate you taking the time.

Kind regards.

TP

[Watson]

So the "big joule thief" is using 2n3055.
Question: Anyone try using an IGNITION coil or
flyback coil?
I guess one problem with ignition is that NEGATIVE is common
for primary and secondary and joule-thief is not happy with
that arrangement.
A flyback, on the other hand, might work -- especially if it doesn't
have a diode on the high-voltage lead -- like some of them do.

-- morpher44

Here's a schematic of an ignition coil driver circuit.

One thing that's great about using a power MOSFET is you can get them in a lot higher voltage. The ones that can handle 200 or more volts and tens of amps are not much more expensive than a 2N3055. But as with a 2N3055, you can still zap them, and then they're good for a paperweight or doorstop.

In the schematic, notice the 1N4005 protection diodes around the IRF640. But I think I would use some 3 amp diodes because the current through the ignition coil might be higher than the 1N4005s can handle. But come to think of it, you could put two or three 1N4005s in parallel and get the same result. They're cheaper and common as dog doo-doo.