First box build and need help

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edyle

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So even insulated, the source wire should not touch the case at all? If someone could send me a few pics of their parallel mosfet box that would greatly help. Maybe of positive connections and mosfet connections.

1:
If it's insulated it should work;


2:
If you can just get it working in pure mech mode it would be the start;
Once you get past that, you can add in the electonics.
 

gandymarsh

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That can't be right; in that diagram the positive goes from the battery to the 510 center pin AND also goes to the switch.
It should go to the switch.
Or if you want to send it to the 510 pin first, then you could do that but you'd have to make sure electricals don't short out on the case;

But it should not go to BOTH the switch and the 510 centerpin
I found the diagram here. I believe it was posted by David84. Here's a video I found of a mod that seems to be built the same as the diagram.
 

dc99

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It goes to the center pin and the switch goes to it because he is switching the low side(ground) and not the high side. The switch thing is a real possibility. Its a common mistake. Make sure you used an N-chn mosfet. Its possible the mosfet is damaged. Some of them can be ruined simply by touching. Can you post what mosfet you used
 
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edyle

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I found the diagram here. I believe it was posted by David84. Here's a video I found of a mod that seems to be built the same as the diagram.


Ok.
I am not going to watch the 20 minute video.
You still can't just send the positive to the topper AND the switch.

You send the positive TO the switch, then send the switch TO the topper;
If you send to positive to the topper directly, then what's the purpose of the switch?

Is the purpose of the switch to activate the mosfet only and not the power?
 

dc99

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Ok.
I am not going to watch the 20 minute video.
You still can't just send the positive to the topper AND the switch.

You send the positive TO the switch, then send the switch TO the topper;
If you send to positive to the topper directly, then what's the purpose of the switch?

Is the purpose of the switch to activate the mosfet only and not the power?
Simply: The ground is floating. The ground is what you are switching instead of the positive. The switch is to operate the mosfet only. Its easier to think of a mosfet as a tiny relay.
 

dc99

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I have some irbl3034s on the way but used an irf510 for my current build. It is an N-channel to 220 mosfet. I am considering gutting this and restarting. it is very possible it has been damaged. If they can be damaged just by touching, how do you handle them?
I like this one IRL3103PBF International Rectifier | Mouser
The 3034 should work just fine though.
Fuses wouldn't be a bad idea
 
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rchrd

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Simply: The ground is floating. The ground is what you are switching instead of the positive. The switch is to operate the mosfet only. Its easier to think of a mosfet as a tiny relay.

I like this one IRL3103PBF International Rectifier | Mouser
The 3034 should work just fine though.
Fuses wouldn't be a bad idea

^ Listen to this guy!

I followed Al USAFs videos to make my box and built it almost the exact same way. You can see my build and some process pics here: my first box mod. - Imgur

A quick note, I've since insulated my negative from sled to mosfet and fully insulated my gate to switch for safeties sake.

And yes you can damage the fet by simply touching it, they're sensitive to static so its recommended to wear an anti-static bracelet while handling them, or just don't rub your socks on the carpet. :p
 

dc99

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^ Listen to this guy!

I followed Al USAFs videos to make my box and built it almost the exact same way. You can see my build and some process pics here: my first box mod. - Imgur

A quick note, I've since insulated my negative from sled to mosfet and fully insulated my gate to switch for safeties sake.

And yes you can damage the fet by simply touching it, they're sensitive to static so its recommended to wear an anti-static bracelet while handling them, or just don't rub your socks on the carpet. :p

Nice work, very clean job. I like the hard line idea
 

JimmyDB

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OP,

Please be very very careful the advise you take... I keep seeing people telling you to run the positive through the switch and not to BOTH the 510 AND the switch, which is flat wrong. The switch is there to activate the mosfet, the main reason to use the mosfet is so you don't have to push the current through the switch.

I like the link from rchrd as it's very simple to see how things are working, and it's correct. I wouldn't go the route of using wiring without insulation and I would have a heat sink on the mosfet, but both of those are something that can be remedied after, and through a variety of means, perhaps there is TIM holding the mosfet to the case, as that would turn the case into a heatsink.

Update: The IRF510 is not suitable (in most cases)... low amp rating, high resistance.
 
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JimmyDB

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I hope what I said wasn't mistaken. Positive from the battery straight to the 510 and another wire from there to the switch and the other side of the switch to the mosfet. It simply powers the mosfet. The drawing that was posted is correct. I still recommend fuses for the batteries. There cheap

Not mistaken by me, you are right on! Only thing I would point out (because I am picky like that ;) is that the positive lead going to the switch could also be a seperate wire directly from the battery pack, it doesn't have to be a branch off the 510... the diagram is 'simple'.

A master kill switch would be nice, but now you need something capable of the amperage :(

Fuses are a great idea, just need to source the right ones that will blow quick enough... but to be honest, the mosfet will only source so much power and then just stop gathering more from the batteries and stop pushing beyond that to the 510... but fuses should just be a way of life, especially for DIY projects. We call these 'unregulated', but they are regulated by the mosfet... they just aren't VV or VW.

Note: 'Regulation' sure doesn't mean 'safe' :)
 

JimmyDB

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Point taken and will wait to receive the irlb3034pbf before proceeding further. Will also look into getting 2 15 amp fuses and will heat shrink a majority of the setup. Thanks again for all the advice. I have been a mech tube guy for months and wanted to take the plunge into boxes.

You know... you don't HAVE to use a mosfet and low amp switch just to do boxes... you can always skip that and just use proper high amp switches :)
 
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