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flyback transformer- identifying the pins

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the self wound primary isnt working. i tried it with the 2n3055 driver also, besides the zvs driver. it isnt giving me any HV output. i have put 10 turns of 2mm thick Cu wire, the pic of which i had already posted. can su1 tell me whats wrong with it?
 
the self wound primary isnt working. i tried it with the 2n3055 driver also, besides the zvs driver. it isnt giving me any HV output. i have put 10 turns of 2mm thick Cu wire, the pic of which i had already posted. can su1 tell me whats wrong with it?

The first thing that comes to mind is that you may be using un-insulated wire. The wire would have to be insulated for this to work.
It would help to have a photo or two of your setup, as well.
Der Strom
 
The first thing that comes to mind is that you may be using un-insulated wire. The wire would have to be insulated for this to work.
It would help to have a photo or two of your setup, as well.
Der Strom

im using insulated wire. and yes i have rubbed off the insulation at the ends to connect with driver. i got 0.8 milli volts as the "high voltage output" with the 2n3055 driver and 0.0 mV with the zvs driver. photo already posted in page 2, and its simple winding, in the same direction, in single layer, as one should wind.

moreover, ppl say we are supposed to use thick wire. and then they say primary coil resistance is 1 ohm???? im getting 0.0 ohm (my multimeter doesnt hv milliohms ) of the self wound primary. is the 2mm Cu wire too thick for it?
 
im using insulated wire. and yes i have rubbed off the insulation at the ends to connect with driver. i got 0.8 milli volts as the "high voltage output" with the 2n3055 driver and 0.0 mV with the zvs driver. photo already posted in page 2, and its simple winding, in the same direction, in single layer, as one should wind.

Okay, that's a good start.
When I suggested a photo, I meant the entire setup, not just the transformer.
Also, did you make any substitutions in the circuits? Different transistors, perhaps, or a different power supply?

moreover, ppl say we are supposed to use thick wire. and then they say primary coil resistance is 1 ohm???? im getting 0.0 ohm (my multimeter doesnt hv milliohms ) of the self wound primary. is the 2mm Cu wire too thick for it?

2mm copper wire should be ok. What exactly is your power supply? The circuit calls for 10-40 Volts, and more than 10 Amps. If I remember right, you're using a 9 volt, 800mA wall adapter? This will not be sufficient. The circuit would work best with something like a car battery, capable of supplying 12 volts, usually at a few hundred amps. See if you can find one of these.
Good luck!
Der Strom
 
Okay, that's a good start.
When I suggested a photo, I meant the entire setup, not just the transformer.
Also, did you make any substitutions in the circuits? Different transistors, perhaps, or a different power supply?



2mm copper wire should be ok. What exactly is your power supply? The circuit calls for 10-40 Volts, and more than 10 Amps. If I remember right, you're using a 9 volt, 800mA wall adapter? This will not be sufficient. The circuit would work best with something like a car battery, capable of supplying 12 volts, usually at a few hundred amps. See if you can find one of these.
Good luck!
Der Strom

i sure theres no problem with the circuit, i hv already chkd the connections and continuity on the breadboard. and as i said, the non-mosfet driver is working with the inbuilt primary but not with the self wound one. i also both the non mosfet and the zvs drivers with 12 V batt. capable of giving 1.4 amps.... and i got almost 0v as high voltage in both cases. and i ended up frying up my 2n3055 ....
 
i also both the non mosfet and the zvs drivers with 12 V batt. capable of giving 1.4 amps.... and i got almost 0v as high voltage in both cases. and i ended up frying up my 2n3055 ....

Okay, I have a couple more suggestions:
1) That battery is not enough for the ZVS driver--that is only a tenth of the current required for a decent arc.
2) Considering the fact that you are getting 0v, the hand-wound primary could be completely backwards. Since the transformer output is rectified, the direction of the winding must be just right.

Other than that, I'm not sure what else to suggest. Perhaps the transformer itself is damaged? Check your transistors (MOSFETS) and make sure they are working properly. Make sure you have zener diodes with the correct values (ordinary diodes will not work here). Check your fast-switching diodes and make sure they are not burnt out. Also check that you are using 2-watt resistors. Any smaller resistors will probably fry.

If anyone else has suggestions, please jump in :D

Regards,
Der Strom
 
well..... i tried reversing the winding direction, changed polarities, but still nothing. maybe this FBT works only with the inbuilt primary.... its construction is special sumhow, maybe, or too worse in other words. :(

heres a pic of my zvs driver:
**broken link removed**
[/IMG]https://www.instructables.com/image/FIYEAZNG9NH8XOG/Schematics.jpg[/IMG]
for fast diodes, i used UF5408.

i called in a TV repairman, but imo, he is just a repairman, nothing else. at first he said that theres no way to make the FBT work without the TV circuit! :p anyways, i hv only 3 days left to complete this project. i needed some 3rd party's opinion.... some of them are:
- while the FBT is detatched from the circuit, he was getting 0 volts in multimeter when the leads r connected either to the primary terminals from the drains of the mosfets, or to primary and centre tap. he said that this shouldnt be happening. do u think this is expected? since he was connecting only 2 leads at a time, would it make a closed circuit?
- he said that the centre tap is already there in the FBT pins, and suggested to use pin 9 as the centre tap. can i really use it? (refer to post 1 for readings)
- he says we hv to provide minimum 100v DC to the primary or else it wont work.
 
well..... i tried reversing the winding direction, changed polarities, but still nothing. maybe this FBT works only with the inbuilt primary.... its construction is special sumhow, maybe, or too worse in other words. :(

I don't think there is anything really special with the internal primary. It could be that 10 total turns is not enough. Try adding more turns and see if your output increases. It may be just that this circuit works best on the older style transformers, as well.

i called in a TV repairman, but imo, he is just a repairman, nothing else. at first he said that theres no way to make the FBT work without the TV circuit! :p anyways, i hv only 3 days left to complete this project. i needed some 3rd party's opinion.... some of them are:
- while the FBT is detatched from the circuit, he was getting 0 volts in multimeter when the leads r connected either to the primary terminals from the drains of the mosfets, or to primary and centre tap. he said that this shouldnt be happening. do u think this is expected? since he was connecting only 2 leads at a time, would it make a closed circuit?
- he said that the centre tap is already there in the FBT pins, and suggested to use pin 9 as the centre tap. can i really use it? (refer to post 1 for readings)
- he says we hv to provide minimum 100v DC to the primary or else it wont work.

A lot of TV repairmen do not know much about the individual parts of the circuit. They only know how to replace them. Let's take a look at some of the opinions:
- It depends on the circuit whether these tests would work or not. I, personally, have not used this circuit, but it seems that you should be getting voltage there.
- I would suggest you use pins 3 and 6 for the primary, and pin 4 as the tap, but you'll need to take some measurements first. Check that the resistance between 3-4 is nearly the same as the resistance between 4-6, and that the resistance between 3-6 is higher than both.
- I have used 12 volts to power a flyback before. It is not as impressive as if I had used 100 volts, but it works. Many people have used this circuit and it has worked, so obviously it can run with less than 100 volts on the primary.

Der Strom
 
By the way, arnab321, how did you make your tap? It occurred to me that my description of how to do it may have been misunderstood. It is hard to see in the photo, so I wanted to double-check.
 
My centre tap is ok, imo. I just scraped off the enamel in the middle of the coil and attached the red wire from the inductor to it. I hv checked for any loose connectons.

And if wounding more turns would give HV, I don't think ten turns would have given 0v.... It would give least a few KVs.

Now I hv only one option left, to use the 555 driver, which can do with the internal primary . One question- would the mosfet irfp250 be suitable for it? Or do I need a higher value? And what's the maximum input voltage and current hat can run the 555 driver blowing the irfp250?
 
If there were not enough turns on the primary, it may not create enough of an electro-magnetic field to induce much current in the secondary. That is why I suggested trying a few more turns.

The IRFP250 MOSFET should work. Check the datasheet for the values, and make sure your power supply doesn't exceed them.
The 555 timer is generally supposed to run on 5-18 volts (again, check the datasheet for the actual values).
 
well, in the 555 driver:
**broken link removed**

im getting 0.5 mm spark :( from a 12V 1A supply. the HV output is measurable using a multimeter---- its about 350V and to my horror, when i connected multimeter, i saw the circuit was drawing only 0.07A....... plz guide me.


in the circuit, im using a ceramic cap of 1 nf (am i supposed to use electrolytic?) , a 100k preset in place of 50k (but i think since its a preset, it can be brought down to 50k by rotating) and irf540 mosfet. the rest are the same components as mentioned in the circuit. im using 1 watt resistors. anything wrong in these?
 
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im getting 0.5 mm spark :( from a 12V 1A supply.

That current still seems rather low. If I were you, I'd keep looking for a better power supply. It will help you a lot.


in the circuit, im using a ceramic cap of 1 nf (am i supposed to use electrolytic?) , a 100k preset in place of 50k (but i think since its a preset, it can be brought down to 50k by rotating) and irf540 mosfet. the rest are the same components as mentioned in the circuit. im using 1 watt resistors. anything wrong in these?

A 1nF capacitor seems awful low--the frequency output must be really high. Try changing it to, say, 100nF (.01uF) and see what that does for you. Also, try using two separate power supplies: perhaps a 9V battery for the 555 part, and link the negative of your 12v 1A supply to the ground of the 9V battery. Connect the positive side of the 12v supply to the "top" part of the primary (referring to the schematic).
Try these suggestions and post what happens. This is due soon, right?
I hope this helps, and good luck with the circuit!
Der Strom
 
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1nf cap is awful low? Its a 555 circuit and lower the capacitor value, higher the frequency. And I was getting the perfect whizz from the flyback....... And the 12v supply im using, can provide 5-6A actually.

well, I replaced the 1nf with a 10pf just out of curiosity. And now I got 3mm sparks..... But I heard no whizz, I.e.the flyback was running in ultrasonic freq. And the current drawn in idle state was still 0.08A, but during sparks, it reached 5.5A.........what conclusion do u draw from the circuit and the "crappy special" flyback?

.fyi, 3mm sparks isn't enough for my purpose. I need to make a lifter fly for the project due on monday
 
1nf cap is awful low? Its a 555 circuit and lower the capacitor value, higher the frequency.

Yes, you're right about that. I forgot that you had a 100K pot, and was thinking the frequency would be too high. It should work, though--that was my mistake.

well, I replaced the 1nf with a 10pf just out of curiosity. And now I got 3mm sparks..... But I heard no whizz, I.e.the flyback was running in ultrasonic freq. And the current drawn in idle state was still 0.08A, but during sparks, it reached 5.5A.........what conclusion do u draw from the circuit and the "crappy special" flyback?

It occurred to me that it may work better to have an adjustable duty-cycle. Here's a circuit very similar to the one you have, with a couple of modifications to make the duty cycle adjustable:

PWM_with_555.JPG

Just be sure to connect pin 5 through a .01uF capacitor to ground (even though it says NC). Also, replace the transistor in this circuit with the MOSFET part of your other 555 circuit. It is definitely worth a try. Many transformers such as these are very "picky" when it comes to the duty cycle of the driver signal. Having everything adjustable may help.

.fyi, 3mm sparks isn't enough for my purpose. I need to make a lifter fly for the project due on monday

Why don't you just use an old computer or TV set? Do you have to build the circuit yourself, or can you just take apart an old CRT device and use that output? That would make your job a lot easier, and the driver is already built ;)
 
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i chked ur circuit. the circuit i hv made already has adjustable duty cycle- thats what the 100k variable resistor is for.

well, the final option for the lifter is the tv itself, but that wont fetch much marks. a self made circuit is more imperssive
 
i chked ur circuit. the circuit i hv made already has adjustable duty cycle- thats what the 100k variable resistor is for.

The 100K pot is for adjusting the frequency, not the duty cycle. You would need a different circuit to be able to adjust duty cycle with a pot as well.

well, the final option for the lifter is the tv itself, but that wont fetch much marks. a self made circuit is more imperssive

You could always take everything out of the case so that all the circuitry is visible. That would look a little more "thrown together" if you ask me :D
 
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