need help with flyback transformer

[tvtech]

24KV from a CRT Line Output Transformer makes a nice long blue 10CM arc when near to earth when running.

Beautiful to see but bad to feel. Very bad.

 

[BrownOut]

Why not use one of the many 555 circuits available for driving the coil? I've made a few, but they need a little more DC line protection from transients than are usually published. I expect the same would be true for lamp dimmers too. A handful of TVS diodes or transorbs and/or a RC filter should do the trick.

 

[Nigel Goodwin]

24KV from a CRT Line Output Transformer makes a nice long blue 10CM arc when near to earth when running.

Beautiful to see but bad to feel. Very bad.

Bit damp there is it?

It's always said that it takes about 10KV per cm to arc in dry air.

 

[DerStrom8]

Bit damp there is it?

It's always said that it takes about 10KV per cm to arc in dry air.

Yeah, that's exactly how I estimate the voltage outputs from my transformers. I think I read somewhere that it's actually more like 1.1Kv/mm, so that would mean 11Kv/cm (in dry air, at sea level, and a whole bunch more ideal situations )

 

[tvtech]

Bit damp there is it?

It's always said that it takes about 10KV per cm to arc in dry air.

No Nigel.

Dry here. I simply take the Anode Cap off and hold it within 10CM of earth. Nice blue arc.
You are welcome to visit and experience it for yourself

Cheers

 

[Nigel Goodwin]

I can remember seeing EHT 'meters' for measuring EHT on TV's, you adjusted a sparkgap until it just started to arc across, and read the voltage off a calibrated scale

Bit crude and nasty, but probably all you really needed for testing EHT - generally if there was a low EHT fault it would be a LOT lower than it should be.

 

[BrownOut]

No Nigel.

Dry here. I simply take the Anode Cap off and hold it within 10CM of earth. Nice blue arc.
You are welcome to visit and experience it for yourself

Cheers

I've done that experiment. It is pretty amazing how long of an arc can be drawn.

 

[unclejed613]

i once worked on a TV where the HV regulator transistor was shorted..... the arc came from under the anode cup and across to a piece of chassis that was 6" away.... humid environment of course... sounded like a cap gun going off.....

i also drove an ignition coil from the output of an amplifier once. a crude ionophone.... you could hear the music from the arc

 

[ben7]

thanks storm ill have a look. what dos it look like? i dont know much baut this stuf.
what im trying to do is connect car ignition coil to HV capacitor 30kv.. one on pic.
i been told i need a rectifier thats in flyback transformer.
is there rectifier that big that i can just go to shop and buy one.. if it is how big dos it have to be.
thanks

With that high voltage and that size of a capacitor you are likely to be able to vaporize a small screwdriver with that! :O

I stick with the caps from psu's that are rated at around 200V and anywhere from 33 to 1000uF.
A nice bank of them charged up then shorted out makes a BIG bang, maybe you would want to use earplugs when discharging that big one! lolz

-Ben

 

[DerStrom8]

With that high voltage and that size of a capacitor you are likely to be able to vaporize a small screwdriver with that! :O

I stick with the caps from psu's that are rated at around 200V and anywhere from 33 to 1000uF.
A nice bank of them charged up then shorted out makes a BIG bang, maybe you would want to use earplugs when discharging that big one! lolz

-Ben

For that matter, why not just use an old disposable camera? The flash capacitor is usually rated 330v, 120uF and can make a heck of a bang. Plus, it's already got the charging circuit in it On top of that, one of these caps discharging through your body probably won't kill you
Der Strom

 

[ben7]

For that matter, why not just use an old disposable camera? The flash capacitor is usually rated 330v, 120uF and can make a heck of a bang. Plus, it's already got the charging circuit in it On top of that, one of these caps discharging through your body probably won't kill you
Der Strom

Are you sure about that?
I'd think it would at least vaporize a nice hole in your skin and mess up your nerves!
They way I charge them is with rectified 120V using two back to back 120V-9V transformers.

However the flash caps are meant for quick pulse discharges, but the other ones I use aren't. I haven't had one fail yet but they are from good mfgs like NCC and Nichicon. I had some "OST" ones before but they spewed goo into my computers psu and never even got put in the bank. >x-P

I should try big HV cap VS little LV cap he he!

We are getting the thread off track though eh?

-Ben

 

[DerStrom8]

Are you sure about that?
I'd think it would at least vaporize a nice hole in your skin and mess up your nerves!
They way I charge them is with rectified 120V using two back to back 120V-9V transformers.

-Ben

I know several people that have touched the pins of a charged flash capacitor and it only made a small mark--hardly even worth calling a burn. I suppose it depends on where you are shocked, but the flash cap PROBABLY won't kill you. Of course, that is only if you don't wire a bunch of them together into a bank--Those can pack quite a punch and could really "mess you up."

I don't think we're getting too off-track. I suggested using a flash cap, and right now we're simply talking about safety. I think it's completely legit.

Der Strom

 

[unclejed613]

banks of caps can have their problems too...... like the "weakest link" failure, where one cap develops a problem and explodes because all the rest of the caps discharge through it at once....

 

[one-zero]

hello dear, i have need a 15w smps circuit with available parts list. if anybody can do it please help me ...

 

[unclejed613]

start a separate thread please.......... one topic at a time.......
i got bit by an 800W Samsung switching supply that had the switching chip popped open.... full charge from two 470uF/250V caps in series through my left index finger from fingertip to the heel of my hand (never place a P/S board in your open hand, handle it by the edges until you've discharged the caps).... left a burn hole in the tip of my finger, and the involuntary reaction of my arm tossed the power supply across the room.... very painful. any cap MUST be treated with respect, especially if it's charged to anything above 25V. in the capacitance formula C=Q/V the charge is the numerator with voltage as the denominator, so as the voltage goes up, the charge is increasing MUCH FASTER.... so even at 0.25uF, the charge is fairly large... as large as a 470uF cap charged to 150V 0.075Coulomb if my math is right

oooh!... ooooh!!! new award for threadjacking!!!!! the Yosemite Sam Award!!!!!!!!! "Mahh nayme is Yosemite Samm, and ahhhma hahjackin' this here thread!!!!!!"

 

[lev77]

thanks guys for all the posts and help...
i found the rectifier on net.. will this work??
**broken link removed**

 

[DerStrom8]

thanks guys for all the posts and help...
i found the rectifier on net.. will this work??
**broken link removed**

Some of those values are cutting it extremely close. 16,000 volts, for one thing, is probably far less than what your ignition coil is putting out. Also, the current rating is significantly less than what you really need. I wouldn't recommend using this type of diode.
Der Strom

 

[lev77]

just finished working on this need to know if its connected ok..

thanks
lev77

 

[ouma]

how many volts does a flyback produce?

 

[lev77]

how many volts does a flyback produce?

hi ouma
im not using flyback any more. this to connect car ignition coil to HV capacitor this is instead on rectifier
thanks
lev77