Touch switch on a 4050c booster chip

[Str8V8ping]

Has anyone got a irl3103 mosfet with touch switch to work on a 4050c chip ? If so do you have a schematic/diagram ? The one thread i found was never answered but someone said they saw a thread with it done sucessfully .

I also have a FDS8433 mosfet on hand if anyone has a diagram with that mosfet with the above setup . I already have pcb's made for this mosfet and reflowed it onto the board already as well (soic)

 

[TomCatt]

.......................

 

[Str8V8ping]

.......................

Does that mean its not possible with those mosfets or any mosfets ?

Also any diagram for the 3103 with a low amp switch on the 4050c ?

I building a really beautiful mod but theres not enough depth for a regular switch so im forced to use a low amp/tact or touch switch . The case also has a built in single battery compartment so a boost chip is the only chip possible to use .

 

[TomCatt]

This has been discussed before, Str8. breaktru has done it with a p mosfet and someone was working on getting an n mosfet working with the 4050C; but I lost that thread and am just waiting for someone to stop by and maybe give us an update.

 

[perlionsmitnick]

It goes something like this.

 

[WillyB]

Well I can't say about a touch circuit, but N-channels work fine if using a small switch.

Nuck's excellent Fistpack guide.

https://docs.google.com/Doc?docid=0AXdaMZo4FKMVZGhqdnE4YnNfNDNjN2Q0cHBoZg&hl=en&pli=1

 

[CraigHB]

It goes something like this.

That should work, but I would put the 1k resistor between the high side (positive) and the top finger contact. The 1k resistor does absolutely nothing where it's located in the diagram and putting it on the high side will protect against inadvertent contact with the the chassis if it's metal and grounded. For example, if the mod is in your pocket with something that's conductive.

Also, since you need to use a high drain battery with a booster, that means an unprotected IMR round cell or LiPo flat cell. I'd put a PTC fuse inline with battery positive as well, as close to the battery terminal as possible.

 

[Str8V8ping]

I put ptc's in all my mods and use IMR's and its a plastic housing with main on/off switch. So that touch switch diagram will work with the mosfets i have ?

 

[CraigHB]

Yes, it should, but I haven't looked at your part's data sheet. Your MOSFET should have a low V_GS(th) or threshold voltage. Should be under 3V, preferably closer to 2V. You have tighter requirements with a booster since you're only working with the voltage of a single cell. The series dual cell mods are more forgiving since V_GS is double that.

 

[breaktru]

It goes something like this.
View attachment 63425

I think I've seen this circuit...... LOL
http://breaktru.com/smf/index.php/topic,215.msg1550.html#msg1550

 

[breaktru]

Yes, it should, but I haven't looked at your part's data sheet. Your MOSFET should have a low V_GS(th) or threshold voltage. Should be under 3V, preferably closer to 2V. You have tighter requirements with a booster since you're only working with the voltage of a single cell. The series dual cell mods are more forgiving since V_GS is double that.

Craig, the Vgs(th) is Min. 1v, Max 2.5v and Rds is 4.9 mOhm.
You are absolutely right about the 1k resistor... DOH. I'll up date the shown drawing.
http://breaktru.com/smf/index.php/topic,215.msg1550.html#msg1550

 

[TomCatt]

Craig, the Vgs(th) is Min. 1v, Max 2.5v and Rds is 4.9 mOhm.
You are absolutely right about the 1k resistor... DOH. I'll up date the shown drawing.
.44 mini Booster Box Mod Variable Voltage

Break, are those numbers for the IRLU3114ZPbF that you used or for the IRL3103 that the OP has?

ETA:
IRL3103
VGS(th) | Gate Threshold Voltage | 1.0(min) | –––(typ) | –––(max) | V | VDS = VGS, ID = 250μA

 

[breaktru]

Yes Tom it was for the 3114 (N-Channel)
The IRL3103 is an N-Channel and VGS(th) is Min. 1v, RDSon is 12mOhm

Update:
My mistake corrected. 3114 is an N-Ch

 

[nicotime]

Yes Tom it was for the 3114 (P-Channel)
The IRL3103 is an N-Channel and VGS(th) is Min. 1v, RDSon is 12mOhm

Huh...the 3114 is an N-Channel...or did I miss something?

 

[breaktru]

error:.................................

 

[breaktru]

Here is the revised schematic for the 3114. Note Nico that it is a N-Channel:

 

[breaktru]

Sometimes I post things without fully thinking it through, and I apologize for that. Yes I erroneously posted that the 3114 was a p-ch when in fact it's an n-ch mosfet.
Also, when I first started using N-Channels for the 04050c and the 08100w I didn't realize that I did NOT have all the Negative wiring breaking through the mosfet and I reported that the N-Ch can not be used with these circuits. Well was I completely wrong. Just make sure that you have ALL of the Neg's going through the mosfet.
In metal tube mods it's easier to use a P-Ch because your breaking only ONE positive to the converter module. However, it's NOT impossible to use an N-Ch in a metal tube. Just reverse the battery and have the positive end down facing the spring cap making the outer case positive and then you will break the single neg going to the converter.

Did I state that correct? or did I put my foot in my mouth... AGAIN?

 

[nicotime]

Hehe...you had me worried for a moment BT...I have used the 3114's in all my mods for some time now...and they work great..never a problem. But I see the 3103 a lot now....which one is better for our application? I dont see a lot of difference in the specs...and I like the size of the 3114. Or is it one of those things that either one will do the same thing with no worries?

 

[Str8V8ping]

Same here . My original question was does that diagram work with the 3103 (only mosfet i have on hand ) . Specs look pretty similar

 

[breaktru]

Yes St8, same circuit