Hey /diy, I wanted to ask for a little check-up on a circut I drew here.
It is supposed to be an autonomous igniter for fireworks triggered by PIR sensor (like when one enters a room, fireworks automatically go off). A 10 ohm resistor is supposed to be burned and what worries me is the possibility of short circut and IC burning.
Would that thing work?
>>1010491
With absolutely no information on what everything is and no reference I can clearly state I have no fucking clue what's going on here.
>>1010491
I don't see the need for the 30 amp fuse, your wires are gonna burn before that fuse goes.
the only thing that is problematic is that you've got your mosfet on backwards.
I haven't used an attiny yet so I can't comment on that.
>>1010491
>igniter for fireworks
>like when one enters a room, fireworks automatically go off
isis pls go
>>1010491
>motion detected "fireworks" igniter
See you on the news soon?
>>1010525
some mosfets have an additional diode inside so they can be used for AC applications. if you want to use them as a switch you have to get the polarity right, otherwise they're simply either always on or always off, regardless of the gate voltage. check the datasheet.
positive lead (after load, igniter in your case) goes into drain, source goes to ground. (with an n-channel mosfet)
also, you don't need the 680 resistor because the mosfet doesn't consume any current on the gate (if that's what you're trying to prevent - remember: it's not a transistor). think of it as a very tiny capacitor. what the 680 resistor accomplishes is that you're making a voltage divider (switching the gate with 4.68 volts instead of 5)
>>1010491
Use a loop of 22g nichrome wire instead if a 10 ohm resistor.
If you are using a resistor, you probably want more like 2-3 ohms.
>>1010560
>MOSFETS ALWAYS
4 terminal MOSFET
>>1010540
First of all this, and also 680ohms is quite much for a gate resistor. In fact almost all of your resistors are chosen wrong and I can't understand why nobody saw this already. Actually not every mosfet fully opens at 5v and that gate resistor is not going to improve on that, especially combined with the pulldown of 70 ohm which yields 1v to gate, and you're guaranteed it will not open at all. Of course the reason you want a gate resistor is to limit the current when turning it on, but whatever, it wont work at all so why bother right?
You did not do the maths, do the maths because nobody else should do it for you.
>>1010598
And your fuse wont do anything useful at all, and the switch (or the ignition resistor) is placed in the wrong position either. But these points are not as important because if you fix your resistors, the circuit might function without fixing these points (if the mosfet actually opens at 5v).
>>1010600
Also last: the mistakes others pointed out should be fixed either of course before it's going to work.
>>1010598
yeh now I see the 70 ohm resisor is 70k, at least you've got that going.
>>1010540
Jumping in here. This is right, except probably any resistor is going to fail because they make them flameproof now. Unless you can find an old ass carbon resistor, use nichrome wire instead.
for the ignitor get some small guage stranded copper wire (alot cheaper than nichrome) and strip off one strand to use as a one-time fuse ignitor.
what do you need to controller for. just wire the pir to the mosfet. or instead of the mosfet use a relay which is easier to wire up and can take a large load on the contacts.
>>1010659
or use something like this (replace ac part with ignitor ciruit)
>>1010625
Ok then it's quite alright, I just want to note that many datasheets specify the threshold voltage at the voltage that the fet will conduct about 100 to 500na. So if your threshold is 4v it might still be tricky to let the fet conduct enough.
>>1010679
Totally not sure about this, but I think fets activate at a certain ratio of base voltage to blocking voltage? And OP has a 'logic level' mosfet that is designed to activate at 5v?
>>1010491
>(like when one enters a room, 'fireworks' automatically go off)
Yes 'fireworks'... not shotgun shells in the bottom of pipes or any such dangerous thing. Yes we all believe you.
>>1010715
>And OP has a 'logic level' mosfet that is designed to activate at 5v?
If that is the case it will work.
>but I think fets activate at a certain ratio of base voltage to blocking voltage?
No, gate threshold voltage is the voltage that needs to be between gate and source before conducting some100's nanoamps.
>>1010820
>not shotgun shells in the bottom of pipes or any such dangerous thing.
Not everybody lives in the united states, or some other shithole. Actually most of the world is pretty civilized regarding to this.
>>1011552
? Uh, booby traps are totally illegal in the us. Do you mean most of the world let's you use deadly force to defend your property when no lives are at stake and you can't even differentiate if the victim is a viable target or a cop with a warrant?
