Winding a flyback secondary
HDF49, Sat Jul 27 2013, 08:40PMI'm working on the power supply for a laser project of mine. I wound a 1315 turn primary, with two layers of paper, superglued in place between the layers, and when winding I brought the end of each layer back to the beginning of the last and carried on winding. I then held the coil under vacuum in oil for an hour, but once rigged up to my half bridge with 250 watts in at 70 volts the sparks were pretty pathetic and the coil shorted out under the oil through the top layer of insulation. The small arcs make me thing that there may have been an internal short in the first place, has anyone got any experience with winding flyback secondaries? I'm aiming for 15kv at 20mA
Re: Winding a flyback secondary
Newton Brawn, Sat Jul 27 2013, 09:18PM
your info could be organized.
specify:
primary max voltage
primary turns
secondary max voltage
secondary turns
a dimensional dwg from your magnetic core
primary and secondary coils sketch also
secondary coil
fist tryal
sketch a coil as:
1320 turns in 20 layers
66 turns per layer
kraft paper 0.2mm thick (or 2 x 0.1mm) between the layers
kraft paper with 10mm margens, one each side of wire.
Then check if the coil fit in the core.
so the voltage between 2 adjacent turns may be 1.41 x 15000/1320 = 16V
the voltage from each layer may be 1056 volts
and max voltage between two adjacent layer may reach 2112V
0,2mm kraft paper imerse in oil is good for 2500V if no air bubles
redesign and add safety coeficients
regards
Newton Brawn, Sat Jul 27 2013, 09:18PM
your info could be organized.
specify:
primary max voltage
primary turns
secondary max voltage
secondary turns
a dimensional dwg from your magnetic core
primary and secondary coils sketch also
secondary coil
fist tryal
sketch a coil as:
1320 turns in 20 layers
66 turns per layer
kraft paper 0.2mm thick (or 2 x 0.1mm) between the layers
kraft paper with 10mm margens, one each side of wire.
Then check if the coil fit in the core.
so the voltage between 2 adjacent turns may be 1.41 x 15000/1320 = 16V
the voltage from each layer may be 1056 volts
and max voltage between two adjacent layer may reach 2112V
0,2mm kraft paper imerse in oil is good for 2500V if no air bubles
redesign and add safety coeficients
regards
Re: Winding a flyback secondary
ZakWolf, Sat Jul 27 2013, 10:43PM
Hi HDF49, I think I can help you out.
First of take a look here
and here
Both flybacks are using the same core and are insulted with 2 layers of overhead projection sheets that are submerged in mineral oil. (not put under a vacuum, which would greatly improve the lifespan). I have recently made two "dry" flybacks both with 2 layers of the projection sheets, and they have a very nice output at 40v in and no corona what so ever.
Since homemade flybacks usually have a high amp output it is better to use thinner wire, I like to use 32 awg for flybacks, It gives it the same characteristics of a factory made one at high turns like(2500+) meaning it doesn't melt metal instantly but can still melt steal if the arc is held for a couple seconds.
Make your layer or insulation as wide as for coil form is.
Hope this helps
Im having trouble upload a picture to this thread, i will try again later
ZakWolf, Sat Jul 27 2013, 10:43PM
Hi HDF49, I think I can help you out.
First of take a look here
and here Both flybacks are using the same core and are insulted with 2 layers of overhead projection sheets that are submerged in mineral oil. (not put under a vacuum, which would greatly improve the lifespan). I have recently made two "dry" flybacks both with 2 layers of the projection sheets, and they have a very nice output at 40v in and no corona what so ever.
Since homemade flybacks usually have a high amp output it is better to use thinner wire, I like to use 32 awg for flybacks, It gives it the same characteristics of a factory made one at high turns like(2500+) meaning it doesn't melt metal instantly but can still melt steal if the arc is held for a couple seconds.
Make your layer or insulation as wide as for coil form is.
Hope this helps
Im having trouble upload a picture to this thread, i will try again later
Re: Winding a flyback secondary
HDF49, Sun Jul 28 2013, 09:54AM
Ok thanks for the help guys, I think I'm going to take the top layer of turns off and add a lot more insulation on top to stop the same again. I've submerged it in a mineral gear box oil, did you use a proper insulative oil?
If all else fails I'll buy some overhead transparencies, and possibly make a zvs driver for more current. I'm ust very annoyed as it was my last spool of wire!
HDF49, Sun Jul 28 2013, 09:54AM
Ok thanks for the help guys, I think I'm going to take the top layer of turns off and add a lot more insulation on top to stop the same again. I've submerged it in a mineral gear box oil, did you use a proper insulative oil?
If all else fails I'll buy some overhead transparencies, and possibly make a zvs driver for more current. I'm ust very annoyed as it was my last spool of wire!
Re: Winding a flyback secondary
ZakWolf, Sun Jul 28 2013, 06:43PM
Yea, i use mineral oil. it works really well and is pretty cheap. You can get it at most stores.
You also wont see very impressive results without a zvs or some kind of half bridge driver, What driver are you using?
ZakWolf, Sun Jul 28 2013, 06:43PM
HDF49 wrote ...
Ok thanks for the help guys, I think I'm going to take the top layer of turns off and add a lot more insulation on top to stop the same again. I've submerged it in a mineral gear box oil, did you use a proper insulative oil?
If all else fails I'll buy some overhead transparencies, and possibly make a zvs driver for more current. I'm ust very annoyed as it was my last spool of wire!
Ok thanks for the help guys, I think I'm going to take the top layer of turns off and add a lot more insulation on top to stop the same again. I've submerged it in a mineral gear box oil, did you use a proper insulative oil?
If all else fails I'll buy some overhead transparencies, and possibly make a zvs driver for more current. I'm ust very annoyed as it was my last spool of wire!
Yea, i use mineral oil. it works really well and is pretty cheap. You can get it at most stores.
You also wont see very impressive results without a zvs or some kind of half bridge driver, What driver are you using?
Re: Winding a flyback secondary
HDF49, Sun Jul 28 2013, 06:53PM
A half bridge of irfp260s, I'm having variac trouble at the moment too so I need to sort out my power supply. I think I might make a zvs driver, less to go wrong, the oscillator of my half bridge section is giving me grief again!
HDF49, Sun Jul 28 2013, 06:53PM
A half bridge of irfp260s, I'm having variac trouble at the moment too so I need to sort out my power supply. I think I might make a zvs driver, less to go wrong, the oscillator of my half bridge section is giving me grief again!
Re: Winding a flyback secondary
ZakWolf, Sun Jul 28 2013, 11:09PM
with a zvs driver im sure that 20ma wont be a problem, especially with a homemade secondary
ZakWolf, Sun Jul 28 2013, 11:09PM
with a zvs driver im sure that 20ma wont be a problem, especially with a homemade secondary
Re: Winding a flyback secondary
HDF49, Mon Jul 29 2013, 08:10AM
Ok, good to hear, I'll get some overhead transparencies and some more wire soon. Thanks for the help!
HDF49, Mon Jul 29 2013, 08:10AM
Ok, good to hear, I'll get some overhead transparencies and some more wire soon. Thanks for the help!
Re: Winding a flyback secondary
ZakWolf, Mon Jul 29 2013, 07:24PM
No problem, let us now how it turns out
ZakWolf, Mon Jul 29 2013, 07:24PM
HDF49 wrote ...
Ok, good to hear, I'll get some overhead transparencies and some more wire soon. Thanks for the help!
Ok, good to hear, I'll get some overhead transparencies and some more wire soon. Thanks for the help!
No problem, let us now how it turns out
Re: Winding a flyback secondary
HDF49, Thu Aug 01 2013, 09:25PM
I will, I have plenty work to do with the rest of the laser too so it may be a while!
HDF49, Thu Aug 01 2013, 09:25PM
I will, I have plenty work to do with the rest of the laser too so it may be a while!
Re: Winding a flyback secondary
HDF49, Mon Aug 05 2013, 03:03PM
I took off the top layer of windings and just hooked it up to my 2kva variac, 60V at 9A, wow, absolutely awesome! My transformer barely gets warm, unfortunately the driver section does, I think I'll have to get a bigger heatsink. I'm having one strange problem though. If I connect the secondary of the variac while the transformer is off to my ZVS, then turn the transformer on and up all that happens is a big hum from the transformer, no output. But If I connect only one lead of the variac to my driver, turn it on, then switch the secondary in to my zvs using my ammeter it works perfectly, any ideas why?
HDF49, Mon Aug 05 2013, 03:03PM
I took off the top layer of windings and just hooked it up to my 2kva variac, 60V at 9A, wow, absolutely awesome! My transformer barely gets warm, unfortunately the driver section does, I think I'll have to get a bigger heatsink. I'm having one strange problem though. If I connect the secondary of the variac while the transformer is off to my ZVS, then turn the transformer on and up all that happens is a big hum from the transformer, no output. But If I connect only one lead of the variac to my driver, turn it on, then switch the secondary in to my zvs using my ammeter it works perfectly, any ideas why?
Re: Winding a flyback secondary
HDF49, Mon Aug 05 2013, 09:45PM
[Edit: Image size]
HDF49, Mon Aug 05 2013, 09:45PM
[Edit: Image size]
Re: Winding a flyback secondary
ZakWolf, Tue Aug 06 2013, 06:40PM
glad to see it working :)
Make sure you don't arc to the core then to your primary. maybe add some insulated primary wire.
Do you have smoothing caps?If so what size? If not add them for sure. i had this problem once, i had to let my caps charge up before i could have a steady current draw.
ZakWolf, Tue Aug 06 2013, 06:40PM
glad to see it working :)
Make sure you don't arc to the core then to your primary. maybe add some insulated primary wire.
Do you have smoothing caps?If so what size? If not add them for sure. i had this problem once, i had to let my caps charge up before i could have a steady current draw.
Re: Winding a flyback secondary
HDF49, Tue Aug 06 2013, 08:05PM
I might do that, thanks. Yeah I've got 1300uF of smoothing, is that just the surge current charging the caps then?
HDF49, Tue Aug 06 2013, 08:05PM
I might do that, thanks. Yeah I've got 1300uF of smoothing, is that just the surge current charging the caps then?
Re: Winding a flyback secondary
ZakWolf, Tue Aug 06 2013, 09:42PM
I think so im definitely not an expert, im just talking from experience. Is you Variac beefy enough for the driver? Btw are you still using the half bridge or the ZVS?
the cap compensates for high amp draw periods but if the cap is trying t charge and supply the driver at the same time it might cause the voltage to drop a lot.
at least thats my take on it
ZakWolf, Tue Aug 06 2013, 09:42PM
I think so im definitely not an expert, im just talking from experience. Is you Variac beefy enough for the driver? Btw are you still using the half bridge or the ZVS?
the cap compensates for high amp draw periods but if the cap is trying t charge and supply the driver at the same time it might cause the voltage to drop a lot.
at least thats my take on it
Re: Winding a flyback secondary
HDF49, Tue Aug 06 2013, 10:05PM
The variac is rated fr 2kva, so yeah I assume so! This is on my ZVS, the results are far far better.
HDF49, Tue Aug 06 2013, 10:05PM
The variac is rated fr 2kva, so yeah I assume so! This is on my ZVS, the results are far far better.
Re: Winding a flyback secondary
ZakWolf, Wed Aug 07 2013, 10:46PM
hmm yeah thats plenty haha, im not sure what causes it. is your arc silent or do you hear a hum ? also will you wind another flyback or is this output enough ?
ZakWolf, Wed Aug 07 2013, 10:46PM
hmm yeah thats plenty haha, im not sure what causes it. is your arc silent or do you hear a hum ? also will you wind another flyback or is this output enough ?
Re: Winding a flyback secondary
HDF49, Thu Aug 08 2013, 08:03PM
Absolutely silent, not modulated at 50hz like it was without smoothing. I'm very pleased with this one, it will strike arcs at 2cm so that's plenty for the laser. I just need to full wave rectify it now.
HDF49, Thu Aug 08 2013, 08:03PM
Absolutely silent, not modulated at 50hz like it was without smoothing. I'm very pleased with this one, it will strike arcs at 2cm so that's plenty for the laser. I just need to full wave rectify it now.
Re: Winding a flyback secondary
ZakWolf, Fri Aug 09 2013, 04:39AM
thats good. Well you can buy a bunch of uf4007's and string them together and seal them in aquarium tubing with oil and make four of them. each urf4007 will give you ~1kv so you may need quite a bit luckily there really cheap
ZakWolf, Fri Aug 09 2013, 04:39AM
thats good. Well you can buy a bunch of uf4007's and string them together and seal them in aquarium tubing with oil and make four of them. each urf4007 will give you ~1kv so you may need quite a bit luckily there really cheap
Re: Winding a flyback secondary
HDF49, Fri Aug 09 2013, 08:55AM
That's what I'm planning on, I've got two hundred and I'm going to make 4 strings of 40
HDF49, Fri Aug 09 2013, 08:55AM
That's what I'm planning on, I've got two hundred and I'm going to make 4 strings of 40
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