Simple Flyback Driver Gives Powerful Arcs

Here are some pictures of my 555 timer flyback driver with two of my flybacks. Unfortunately, I didn't have the parts to build a ZVS flyback driver, so I decided to improve my existing driver. The setup us simple, a 555 timer oscillates at a frequency determined by a variable resistor, and turns on and off a MOSFET that I found inside of an old computer power supply. The MOSFET is supplied with about 20 volts from two old lead acid batteries from an electric scooter. The arcs are quite impressive, especially for a 555 timer driver. I can draw sparks that are almost two inches long!

Sorry, no pictures of the driver yet, or of the longer sparks.

TheTeslaWarrior says: Dec 30, 2009. 8:32 PM

do those arcs look very lethal or is it just me?(just curious)

Xellers (author) in reply to TheTeslaWarriorDec 31, 2009. 9:58 AM

Unfortunately, I never measured the power that the circuit was using - so I can't even make a rough estimate at the secondary side current, but the arcs are not quite as hot as those from a neon sign transformer, so I would guess that this will not kill you (although I wouldn't want to be shocked by it either!).

TheTeslaWarrior in reply to XellersDec 31, 2009. 5:05 PM

i just noticed the deadly orange-ness around the arc... usually indicting high current, after all 7-10 ma is all it takes

Jimmy Proton in reply to TheTeslaWarriorAug 6, 2010. 6:21 PM

actual 10mA is unlikely to kill you

croslandjr123 in reply to Jimmy ProtonDec 17, 2010. 1:19 AM

Hmm... yeah. Some people say the lethal rate is 10mA, some say 30mA or even 100mA(!). The people who say 100mA is the lethal rate are obviously wrong. But it usually depends. Sometimes 10mA kills, sometimes is doesn't. Same goes for 30mA but it's more likely to harm you. People have survived power from a MOT, but this does not mean that I believe anymore can survive 500mA.

Jimmy Proton in reply to croslandjr123Dec 17, 2010. 4:50 AM

i think that 10mA DIRECTLY across the hear will kill you but it doesn't always go through the heart 30mA can cause damage to a healthy heart but probably not kill and 70mA is likely to kill and if your extremely lucky you can survive a MOT. i also think it takes around 90V under normal circumstances to over come the resistance of both your hands.

dumle29 in reply to Jimmy ProtonJul 29, 2011. 12:41 PM

6 mA across the heart is enough

doepy in reply to dumle29Aug 10, 2011. 12:54 AM

thats true

croslandjr123 in reply to dumle29Jul 29, 2011. 4:37 PM

In some cases, yes. You'd have to be pretty unlucky.

my wookie in reply to croslandjr123Apr 3, 2013. 3:54 PM

who cares, just avoid getting shocked by anything above 5 mA cause after that it just hurts.

doepy says: Aug 10, 2011. 12:51 AM

wats the schematic

jj.inc says: Jan 3, 2011. 9:42 PM

Why the fly-back if you are just making arcs, it seems a lot more complicated than taking a square of iron and winding two coils and upping the voltage like that in every wind. If you run it on US house power (120V), wind 5 on the primary and 50 on the secondary you already have 1200V, then if you do it a second time (I haven't actually done anything like this, its just from what I have read) you will have 12000v, and so on. You may need more than 5 I have know experience, but it still looks easier than a fly-back.

Xellers (author) in reply to jj.incJan 4, 2011. 4:22 PM

Unfortunately, winding your own 60Hz transformer is nowhere near as easy as it is to use a flyback transformer! There are so many problems with this proposition that I cannot spend the time to list all of them. If anyone else wants to explain why you can't do this, please be my guest.

jj.inc in reply to XellersJan 4, 2011. 6:09 PM

Well that was my question, I am not an expert and I wanted to know if someone could help not tell me I'm just wrong and not say anything else.
Also is instrucatbles having server issues.

dumle29 in reply to jj.incJun 19, 2011. 4:57 PM

well, when making a traditional transformer like you suggest has a ton of problems, first of all, the iron core needs to be made of several laminated sheets of iron, or it would cause self induction in the core, and i would get readhot. second of all, you will need at least 300-600 windings on the primary or it would be like shorting the plug.

jj.inc in reply to dumle29Jun 19, 2011. 9:44 PM

Thanks

volthead says: Jan 30, 2010. 3:44 PM

You should try getting it to resonate. Put a 0.22uF cap in parallel with the
mosfet. That should snub the negative pulses and protect the mosfet (not to mention 3 inch arcs).