Soldering SOT23's is fun!

[Kewtsquirrel]

So, I promised someone a passthru, and haven't been able to find the time lately to get it done for them. Feeling bad, I figured I'd go ahead and use some of my new mosfet's on their mod, extending the life of the switch by a great deal and improving performance.

SOT23's seem bigger when you're looking at the datasheet, when you actually get them in, it's a bit more daunting. I won't lie, a few of the compatriots of the mosfet that finally made it laid down their lives for the cause. I think this thread should be a memorial to those fallen fets.

26AWG wire and 801 connector for scale.

Finally, the one that those brave, brave transistors gave their lives for.
Front:

Back:

Specs:

Serpac C-4 Smoke Translucent Enclosure - Mouser - Forgot P/N
Extra-large (12mm) tact switch - Newark SKU: 67P3635
Super-Bright blue LED - Mouser - Expensive, maybe a buck? Brighest blue LED available.
2 100ohm 1/4 watt resistors
Vishay N-Channel Mosfet SOT23 20v 3.77A low RdsON low threshold - Mouser P/N 781-SI2312BDS-E3
510 Connector (Nerf brand! ^_^)
510->901 adapter (Nerf brand! ^_^)
BE901 atomizer
Self-mixed watermelon 20mg liquid, 30% glycerin, 20% watermelon, 50% blip labs nic solution+PG
Lots and lots of swearing
3 dead mosfets - RIP

 

[caesar]

RIP mosfets, ESD is a *****.
Don't wear anything that can charge you electrostatic while handling them. ESD protected soldering station is also a must.

Pretty nice light effect!

 

[Kewtsquirrel]

RIP mosfets, ESD is a *****.
Don't wear anything that can charge you electrostatic while handling them. ESD protected soldering station is also a must.

Pretty nice light effect!

I do my best work naked, so that helps.

 

[Cisco]

I do my best work naked, so that helps.

why on earth would you get those mosfets in a sot23 package....?

You should use TO92 or TO220 package,much easier to work with....


Cisco...

 

[Kewtsquirrel]

The TO220 is too big and I can't find any TO92's that have a low enough Rds(on) for my liking. Found some 223s that should work, they should be here Monday.

 

[Stormynights]

I do my best work naked, so that helps.

Is that why you haven't done any more video's?

 

[SmokinScott]

What the heck are these mosfets, and why would you use these instead of a 5v voltage regulator?

 

[Kewtsquirrel]

Two completely different things Scott, a 5vreg would actually exacerbate the problem instead of fixing it. The vast majority of us use switches that are grossly underrated for what we're doing. A 50mA tact switch *will* start to degrade over time and finally stop working if you're pushing 1500mA through it. Using a MOSFET (Field effect transistor) you are essentially controlling the atomizer with a relay instead of the switch. The switch only turns on the mosfet, and is pulling a couple mA of current to do it - all of the current the atomizer requires is funneled through the mosfet instead.

 

[Dave Rickey]

Speaking of which: Just as Nerf was figuring out mosfets, I found some tactile switches that should be able to take the abuse we're handing out a lot better:

E-Switch 320 series, available in many different cap colors and shapes (has a stock locator to find retailers with particular combinations or pieces), rated 25mA at 50V, which works out to about 350mA at 3.6V, so we'd be overdriving them at a factor of 3 instead of 6 like the current 50mA@12V tactiles everyone is using. But the word I get is that the interior components are sealed in a nitrogen atmosphere, and they should actually hold up quite a bit better at such low voltages, even though it's outside their rating envelope. Half an inch on a side and only about 4.5mm high aside from the button, it comes in a high-stem variety where you can thread the stem via a 2.5mm hole through up to 6mm of chassis shell, and still lock the button pad on top. Button pads in every color and shape imaginable, including LED versions.

--Dave

 

[Sci]

E-Switch 320 series, available in many different cap colors and shapes (has a stock locator to find retailers with particular combinations or pieces), rated 25mA at 50V, which works out to about 350mA at 3.6V, so we'd be overdriving them at a factor of 3 instead of 6 like the current 50mA@12V tactiles everyone is using. But the word I get is that the interior components are sealed in a nitrogen atmosphere, and they should actually hold up quite a bit better at such low voltages, even though it's outside their rating envelope. Half an inch on a side and only about 4.5mm high aside from the button, it comes in a high-stem variety where you can thread the stem via a 2.5mm hole through up to 6mm of chassis shell, and still lock the button pad on top. Button pads in every color and shape imaginable, including LED versions.

--Dave

Did you notice that they have a sample request form? I put in a request for 5 of those switches, I'll let you know what happens.