Touch switch (pocket-friendly, low-profile and cool)

[kinabaloo]

A pocket-friendly, low-profile touch switch can be made quite easily from two successively connected transistors (high gain arrangement). Suitable transistors would be BC109C for the first (left) and a 2N3055 for the second. The atomiser would be connected in parallel with the LED and 470 resistor.

Two small bolt heads would make a nice contact set.

Here is a suitable circuit:

Source (includes a variety of alternative methods, and a single touch pad design): Touch Switch​

Transistor info: http://www.melektronikos.com/en/books/keu/04.htm

 

[nicowolf]

Wow. This is way over my head. I might be ready for this in a few years. Can you make one and give us a step by step how to with either pics or video?

 

[Fox3]

WIth SMT parts that could go in the barrel (dragging out parts bin and firing up the hot air iron .

 

[kinabaloo]

I forgot to mention perhas the best advantage: no moving parts. On the downside though the second power transistor is quite big that I mentioned, but there might be a smaller one that can still handle the power.

I think I prefer the tactile feedback provided by a button, however

But the touch switch has definite advantages and so I just throw it out there as an idea ...

 

[mnealtx]

Has anyone made this, yet?

Does the circuit work with the component values shown with the atomizer in place of the LED/resistor?

 

[Vaporer]

Kinabaloo,

Nice........
A FET with a 1K resistor on the output can handle more current even in SMD.

 

[Scubabatdan]

Sorry wrong thread....

 

[Lee1111]

Hey guys I wired one of these up like raidy describes using a mosfet.

How can you even use the smallest switch?
Everyone knows the problem. They want to use small switches, but could not withstand the current. This little circuit for much the same as $ 2 solves the problem. It is so sensitive that even a not too dry enough fingers to turn the atty. Or any small switch. The current on the switch is now less then 1/1000 mA.


I have made this post a separate thread, since the circuit can be used very universally.

I used the same order for the legs and wired exactly the same. One exception-Ratshack didn't have 2-4 M ohm range so I tried two 1M wired in a chain. The problem is the atty keeps staying on as soon as I connect power. Maybe I need to add a third/fourth one? I'm not wrong about that am I? Two 1M ohm resisters in series is 2M ohm? Any help is great.