It's a transformer.

It increases the voltage by the turns ratio.

It doesn't make energy from nothing, the voltage is increased so the current is reduced, remember VI = Power.

Normally the ouput voltage is even higher than you'd expect be cause the current is suddenly interrupted in the primary causing a high voltage which is multiplied again by the secondary.

Look up transformers and ignition coils on Wikipedia.

You could also ask your physics theacher he/she will probably be able to offer you an excellant explanation.

__________________

I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.

Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

 

I can't believe how long this thread has been going. Must be the longest active thread here.

I would think the purchase price of a manufacture device would well worth the money if you shock somebody and they die. Always blame the manufacturer, some measure of legal protection. Kill somebody with a home built unit, and its manslaughter, and a judge will decide how justified you were to use deadly force.

To have any chance of being effective, you would need to practice and train yourself to use it effectively in a real situation. I'd think that time would be better spend learning a more effective means of self-defense. I mean, what are you going to do if the batteries are dead? What if you fumble and drop it? Gets knocked out of your hand? Bummer if it gets turned back on you... I just wouldn't want to put much reliance on a single defense. Got to be ready to do what you can with whatever is available...

 

I agree, take up a martial art, perhaps Nigel can advise you.

__________________

I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.

Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

 

hmmm, i have noticed that too. why do so many people want to build a stun gun?, even though it's not likely to kill you, not many people appreciate being shocked no matter how many volts/milliamps it is. And in most places i'd imagine that they would be illegal?

__________________
The 3 laws of science....
1. If it smells bad, It's chemistry.
2. If it's mushy, It's biology.
3. If it doesn't work, It's physics.
www.laserchat.org IRC chat for laser and electronic related stuff.

 

They're illegal over here in the UK.

__________________

I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.

Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

 

yes i use breadboard to built this circuit and it is the easiest way to built circuit

 

Is there any country that they are not illegal?

__________________
The 3 laws of science....
1. If it smells bad, It's chemistry.
2. If it's mushy, It's biology.
3. If it doesn't work, It's physics.
www.laserchat.org IRC chat for laser and electronic related stuff.

 

Yes, please read my previous response.

__________________

I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.

Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

 

I suggest you read the post you replied to again!

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

 

I don't see how a home made stun gun will be more illegal than a ready made one providing it doesn't kill any one.

I do agree that if it's off the self then you can blame the manufacturer which won't be the case if you've built it yourself.

Also stun guns are illegal in many countries anyway.

__________________

I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong.

Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

 

I wonder the TIP31 will not be destroyed by the back emf?

__________________
bananasiong

 

Yes, probably.
If the stun gun doesn't have a victim as its load then the back emf will increase until something conducts. It the output sparks then the back emf will be limited. If there is no spark then you can say goodbye to the TIP31 transistor.

__________________
Uncle $crooge

 

Can't just use a diode to protect it? Or this will reduce the stepped up voltage?

__________________
bananasiong

 

A protection diode would reduce the stepped up voltage.
A real stun gun uses a high voltage Mosfet to drive the transformer.
It also uses a transformer designed for high voltages, not just a dinky little audio transformer.

__________________
Uncle $crooge

 

Just to confirm. If no diode for protection, the stepped up voltage is higher than the step up ratio because the back EMF is also stepped up. When a diode is added, the stepped up voltage is the product of the ratio and the input voltage of the transformer, right?
The high voltage MOSFET you meant is the one that can handle the fly back?

*sorry for the nobbie questions, I'm not good in ac.

__________________
bananasiong