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FrozenGate by Avery

Mosfet??? to prevent switch melting???

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pados1002_Alex_13

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Jan 14, 2021
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Hey guys, on my way to build my first ~2W laser i decided to use the housing of my old skyray torch... Beast of a housing but for a newbie like me there's an issue. How to avoid melting instantly it 's tiny switch?
Thanks too @Giannis_TDM , i m looking a way to pass the current through a mosfet circuit. But i have no idea how make it work, no matter how much i read. The switch has two cables and it s a push switch of i believe a max of 50mah... I would be grateful if someone can guide me on how to build a circuit or even give me a new idea!
 

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The switch can not handle all the current i did pen laser builds and the push buttons would melt so i purchased a pack from china just in case but i stop building high power lasers in pen style you may have to use another switch i tried many things still nothing helped
 
Thank you so much @FireMyLaser ! I 'll try that for sure!
And of course i would appreciate if you could suggest a mosfet for the job... I actually don't know how much current will the Astral driver need from the battery to drive a 2W diode but i m looking for a 5A mosfet... No idea if it s too much or not...
 
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If you can drill a larger hole and do not need to use a mini-push button A different switch would make more sense than playing with that one and making a mosfet device to go with it.

Check on Ebay --hundreds of low cost push button switchs offered that are not large with free shipping from China. Search "push button switches" on eBay.
 
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I doubt you will find a miniature push button that can handle ~2A to run a 2W diode. Don't trust whatever it says on ebay.
Offloading the switching task to a mosfet lets you use any button you wish and not worry about it melting.
 
@Encap i have already ordered a ton of things from ebay, alie, banggood etc... Switches, cables and whatever 's coming in my mind that i may need... Of course i ll drill a bigger hole if I can't make it with the mosfet... But i want to minimize the hardcore "modding"!
@FireMyLaser i agree with you that those switches are not trustworthy so that's why i want to learn more about mosfets and how to use them in a circuit! And i try to figure out how to find a "logic level" mosfet but i can't find that description, except for a couple of exceptions. What should i look for? My diode needs 1.8A, so what the safest value for a mosfet current to choose? 2A or more?

Sorry for asking so many things but as i said, NOOB here!
 
You haven't shown what other parts you use. There is no size fitts all MOSFET. It needs to have a low on resistance at the avalible gate voltage you supply, and be rated for the current, say roughly 10x what you will actually use so it will run cool without any heatsink. It can also be very tiny so it is up to your soldering skills then.
 
@FireMyLaser it will be a 1.6w diode osram pl450b with astral superdrive v... It will run on 18650 in series to have the recuired voltage... I m planning to use a boost driver at some point because it will help me more with the housing, to have the batteries in parallel... So 4-8v... But in the future if i manage to complete this project i will try with something bigger in watts... I hope those infos are enough for some teaching 😁
 
I told you all you need to know, you can at least try to find one yourself. Look on Digikey and use their filters to sort out the MOSFETs that won't fit these specs.
 
@FireMyLaser i have one last question... It s about the gate voltage... Which parameter shows me at which voltage the diode is on and the current flows rully? VGS, VGS(TH), something else? I know that the diode can open so the current to flow l, but not necessarily, completely.
I hope that's the last answer i m gonna need!
 
@FireMyLaser today finally the MOSFETs and resistors arrived and i tried your circuit! And yes ot worked! Thanks man! But i have one question... How do i choose the correct resistor? What does it depend on? For example i used an 1ohm 1w resistor and it worked.
 
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