MOSFET Tail Switch Clickie

tsteele93 · May 19, 2012

This seems like a REALLY cool idea, but $50 is crazy expensive for a switch. I wonder how hard this really is and what it could be done for here with some of our brighter minds at work?

http://www.candlepowerforums.com/vb...e-for-Z41-and-variants.&p=3779589#post3779589

AND CPF seems to be down at the moment... odd. I'll look for a cache version.

CLICK HERE FOR THE GOOGLE CACHE VERSION

sinner · May 19, 2012

Awwhh man!! Was it a teaser? :na:
My hopes went instantly high up when i read the thread title.. Alas a $50 switch is what we all need.. I'm sure there'll be an alternative for like less Amperage ~10Amps.

Meatball · May 19, 2012

No matter the current rating here, the MOSFET costs as little as .50/ea and as high as 2.00/ea.

The unit would need to be a self contained unit with connections for the external switch, and the load circuit. The unit would contain a MOSFET, the 3V cell, and MAYBE a resistor.

The unit would have to be a reasonable size so it could be integrated in many tail caps.

tsteele93 · May 20, 2012

sinner said:
Awwhh man!! Was it a teaser? :na:
My hopes went instantly high up when i read the thread title.. Alas a $50 switch is what we all need.. I'm sure there'll be an alternative for like less Amperage ~10Amps.

Yeah, I was thinking some of our resident geniuses here might be able to tackle this with a much less expensive option. Seems like this could be done for $10? No?

Maybe not, but $50 seemed WAY HIGH for the parts involved...

sinner · May 20, 2012

I will have to agree with Meatball on this one, There are more than two basic components besides a switch a Mosfet itself and a CR2032 Lithium Primary 3V battery (gate needs a push doesnt it) So the tailcap as we see are more of 30mm or maybe longer than that, look ugly as s*** why not use a McClicky.. and there you go. Problem Solved.. :na:
I mean , we just need a switch 4Amps MAX for a Boost Driven 1.8A Single Cell build..
$7 a pop does seem reasonable if it works out 20,000 clicks/lifetime

tsteele93 · May 20, 2012

Current - 25A+

Voltage - 12V MAX (20V available for $10 more if needed)

0.0034 ohm Rds(on) MOSFET resistance

Beryllium copper spring(95% more conductive than spring steel), Pure silver plated for extra conductivity, 24K gold plated contact area.

Gold plated contacts from the FETtie to host.

Threaded brass body acts as heatsink for MOSFET in high amperage applications.

Panasonic 1216 coin cell included

"Reverse" Clicky operation.

benmwv · May 20, 2012

Not a complex design at all. You are paying for the "package" mainly. It cost so much because it's unique, and all you have to do is screw it in.

If you want this in one of you hosts just get a MOSFET and a battery and cram it in behind the spring. There is no need to pay so much, or even make a pcb for it, because all hosts are different sizes.

Tsteele search this on digikey:
SI4378DY-T1-E3CT-ND

tsteele93 · May 20, 2012

benmwv said:
Not a complex design at all. You are paying for the "package" mainly. It cost so much because it's unique, and all you have to do is screw it in.

If you want this in one of you hosts just get a MOSFET and a battery and cram it in behind the spring. There is no need to pay so much, or even make a pcb for it, because all hosts are different sizes.

Tsteele search this on digikey:
SI4378DY-T1-E3CT-ND

That is what I was thinking, and it is a pretty neat design. Especially if you are looking for a high current switch. More or less using the mosfet as a relay if I am reading it right.

Basically using a low current switch to trigger a high current switch?

benmwv · May 20, 2012

Yeah, pretty much.

If you just google "mosfet switch" you will get tons of results showing how to do it.

Basically, the drain of the MOSFET connects to the case, the source goes to the battery negative and the switch connects 3v (from the coin battery) to the gate.

grenadier · May 21, 2012

Seems pointless; a clicky switch is hardly a noticeable loss in the entire system.

tsteele93 · May 21, 2012

I think there were some problems finding clickies for higher current builds. This came up as a neat idea for a cleverly (over?) engineered solution.

Hiemal · May 21, 2012

Problem is that doesn't work if you need a case positive build.

And, that is so overengineered that it actually hurt a little bit to read about it. xD

Blord · May 21, 2012

It looks good but $50 for a clicky is kinda pricy. Can't we just find some heavy duty mechanical clickies ? I am sure for that price there are good mechanical alternatives.

tsteele93 · May 21, 2012

Blord said:
It looks good but $50 for a clicky is kinda pricy. Can't we just find some heavy duty mechanical clickies ? I am sure for that price there are good mechanical alternatives.

$50 is WAY overpriced. I was thinking it could be done for $5-$7. But I could be wrong...

Maybe I will work on one.

MOSFET Tail Switch Clickie

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