Stun Gun

[HarveyH42]

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...

 

[Hero999]

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

 

[things]

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?

 

[Hero999]

They're illegal over here in the UK.

 

[usmankhan]

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

 

[things]

Is there any country that they are not illegal?

 

[Hero999]

Yes, please read my previous response.

 

[Nigel Goodwin]

Yes, please read my previous response.

I suggest you read the post you replied to again!

 

[Hero999]

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.

 

[bananasiong]

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

 

[audioguru]

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

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.

 

[bananasiong]

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

 

[audioguru]

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

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.

 

[bananasiong]

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?

A real stun gun uses a high voltage Mosfet to drive the transformer.

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.

 

[audioguru]

If no diode for protection, the stepped up voltage is higher than the step up ratio because the back EMF is also stepped up.

Yes.

When a diode is added, the stepped up voltage is the product of the ratio and the input voltage of the transformer, right?

Yes.

The high voltage MOSFET you meant is the one that can handle the fly back?

Yes. The max collector voltage of a TIP31 transistor is 40V to 60V. The max for a high voltage Mosfet is hundreds of volts and it has an avalanche diode built-in to protect it.

 

[bananasiong]

Thanks
Just read through wiki, is any diode that is used to protect the circuit from back EMF called avalanche diode?

 

[chemelec]

Actually Most REAL Stunguns just use Transistors and a transformer (T1) for the Initial Stepped-up Voltage of 200 to 400 volts.

Than an SCR to trigger this 200 to 400 volts to pulse this into the second transformer (T2) (a Trigger Coil) to get the Really High Output voltage.

Ususally Both these transformers are Custom Made.
"But Especially T2".

 

[Hero999]

I agree chemelec, that's what I would do if I wanted to build a stun gun.

 

[audioguru]

is any diode that is used to protect the circuit from back EMF called avalanche diode?

An avalanche diode breaks down and conducts at its avalanche breakdown voltage and holds the voltage like a zener diode. Mosfets have it built-in.
This diode will protect the Mosfet from short duration high voltages at fairly high currents. It has a much higher voltage across it when it breaks down than a diode across an inductive load which is a "free-wheeling diode" so the avalanche diode gets very hot when it is working.

 

[TheVictim]

I'd step up the output of an invertor through a transformer and then use a Cockroft-Wolton multiplier to step it up again as DC.