Touch sensor switches
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Serial describes the electrical arrangement of the batteries - they are connected one after the other. "In series" is another valid description. Both are right, neither are wrong - simply a different word choice.
Can we end the silly word games, since everyone now understands what I meant, and get back to figuring out touch switches?
I think the bottom line is that for our application the touch switch may not be cost effective or small enough. On the cost side the RS 3 amp momentary switch is the best bang for the buck. I wish I could find one smaller and rated at 2 amps. Most smaller switched are only rated for 0.5 amps which will burn out sooner than later.
This is a good project crazyhorse, It will benefit the mod community. The idea is great but fitting one in a 2xAA box will be difficult. Good luck.
Kevin
This is a good project crazyhorse, It will benefit the mod community. The idea is great but fitting one in a 2xAA box will be difficult. Good luck.
Kevin
you can get a MOSFET from Newark or digikey for less than $1 and a board from sparkfun for $2 and a resistor for a coue cents. To me this seems just as cost effective as the radio shack switch. Plus the benefit of space saving as the chip and board is much smaller than the RS switch.
Well, here are the board dimension that Ralph gave you:
I think it will be bulky.
Kevin
Ceasar made one with a custom board that was 2 cm x 1 cm. There is more than one way to skin a cat. The MOSFET that I will be using is only 2mm x 3mm.
I will post pics next week of a USB
I will also keep the cost under $20 for the completed box
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Now, that changes everything. I'll look forward to your results. My problem lately is that it's not as easy to solder small circuits as when I was younger. I have too much hand shake, probably too many analogs.
Kevin
I should have some 2505 fets here SMD type. I sold them for circuit mods I made on small cheap rc gear to run more than one motor. The motors drew 380ma continously.
I'm pretty sure the 2505 will handle just over 1amp. I'd need to find the schematic I had drawn up and try to find the parts. had the resistors and also the opposite junction type too.
I bought them 100 at a time because of the high shipping cost of just getting a couple.
It was to expensive for people to use my designs so I provided the parts at a reasonable price. The circuits on the rc gear were fed by an op-amp so a 1k resistor to ground on the input was needed to keep them in an off state from "noise" and leakage going to gate. No accidental "ons" that way.
I may still have 50-75 or so around that I would mail 1 or 2 like I used to if anyone is interested, I'll look for them. The circuit is still posted on the rc forum. Cataract surgery in both eyes kinda slowed me down and new little cheap other ones came in and interest faded.
Let me know if there's any interest in the parts and I'll look for them. They are still sealed in the factory strip/roll.
I'm pretty sure the 2505 will handle just over 1amp. I'd need to find the schematic I had drawn up and try to find the parts. had the resistors and also the opposite junction type too.
I bought them 100 at a time because of the high shipping cost of just getting a couple.
It was to expensive for people to use my designs so I provided the parts at a reasonable price. The circuits on the rc gear were fed by an op-amp so a 1k resistor to ground on the input was needed to keep them in an off state from "noise" and leakage going to gate. No accidental "ons" that way.
I may still have 50-75 or so around that I would mail 1 or 2 like I used to if anyone is interested, I'll look for them. The circuit is still posted on the rc forum. Cataract surgery in both eyes kinda slowed me down and new little cheap other ones came in and interest faded.
Let me know if there's any interest in the parts and I'll look for them. They are still sealed in the factory strip/roll.
Vaporer, I'm interested but the interest is pointless if all I have to go on is arcane schematics and technobabble. If there was a simple ABCD set of written instructions, I'm sure we all could build us a touch switch. Until someone steps up to dazzle us with brilliance rather than baffle us with bullchit, we plebes are pissing into the wind.
Hi Crazy,
I was wrong on the 2505's. I have the IRML2502 N channel and the IRML6401 P channel.
The 6401 is rated at 4.3 amps SMD size. I'm sure thats time limited not continous. I got them from Digikey.
I can look the specs back up. Wasn't there a simple schematic in the begining of the thread? It looked pretty simple. It was a FET and a resistor. Thats about as simple as it gets. Only other thing would be a pic indicating wires.
Did anyone try it to see if it will flip on to run an atty coil?
I havent kept up here. Been watching CA go down the drain on the new SB 400 bill and making my failed mini pipe a manual. While trying to find out the best way to get nic from tobacco in the event of a ban. Been keeping me busy......lol
I was wrong on the 2505's. I have the IRML2502 N channel and the IRML6401 P channel.
The 6401 is rated at 4.3 amps SMD size. I'm sure thats time limited not continous. I got them from Digikey.
I can look the specs back up. Wasn't there a simple schematic in the begining of the thread? It looked pretty simple. It was a FET and a resistor. Thats about as simple as it gets. Only other thing would be a pic indicating wires.
Did anyone try it to see if it will flip on to run an atty coil?
I havent kept up here. Been watching CA go down the drain on the new SB 400 bill and making my failed mini pipe a manual. While trying to find out the best way to get nic from tobacco in the event of a ban. Been keeping me busy......lol
I've asked a couple folks that have done it for some input...hopefully they'll post here with some ideas - even if it's just general specifications to give us an idea of what MOSFET or transistor to look for, and a value recommendation for the gate or base resistor it would still be a big help.
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mnealtx,
Here is a link to a very simple one that should work. The load is the atomizer wires.
I haven't cross referenced the FET listed yet and it may work fine at our voltages, but I have 2502' and 6401's if someone wants to give it a try before I can get to it. They will work in the same voltage range as our PV's. The rc gear I used them in used Li Poly batts , the same range and cutoff.
I don't have a failed switch yet, but I can see where it would be a neat substitute.
The contacts should be recessed or covered, when not in use, to prevent accidental "on's".
The 4.7m resistor can be a lower value as long as it allows the FET to turn on. All it's doing is keeping the FET off during idle when the contacts aren't being touched.
Circuit - FINGER TOUCH ACTIVATED SWITCH - Circuits designed by David A. Johnson, P.E.
Maybe I can solder one up in the next day or so.
Hope this is what you guys are looking for.
Here is a link to a very simple one that should work. The load is the atomizer wires.
I haven't cross referenced the FET listed yet and it may work fine at our voltages, but I have 2502' and 6401's if someone wants to give it a try before I can get to it. They will work in the same voltage range as our PV's. The rc gear I used them in used Li Poly batts , the same range and cutoff.
I don't have a failed switch yet, but I can see where it would be a neat substitute.
The contacts should be recessed or covered, when not in use, to prevent accidental "on's".
The 4.7m resistor can be a lower value as long as it allows the FET to turn on. All it's doing is keeping the FET off during idle when the contacts aren't being touched.
Circuit - FINGER TOUCH ACTIVATED SWITCH - Circuits designed by David A. Johnson, P.E.
Maybe I can solder one up in the next day or so.
Hope this is what you guys are looking for.
Thanks, Vaporer - I can't access the site right now, but I'll try again later to see the schematic.
Looking at the 2502 (if it's the 25C2502), that FOR SURE should handle anything we could throw at it in regards to e-cig use!!
Looking at the 2502 (if it's the 25C2502), that FOR SURE should handle anything we could throw at it in regards to e-cig use!!
That looks almost like the one I posted with an extra resistor to protect from shorts across the touch pad.
The MOSFET acts like a switch. If the Gate is low (negative volts) the switch will be open. If the Gate is high (positive volts) the switch will make, connecting Source and Drain.
The resistor keeps the Gate low until you touch the contacts. As long as your skin has less resistance than the 4.7meg resistor then it will turn on.
Hope that helps.
The MOSFET acts like a switch. If the Gate is low (negative volts) the switch will be open. If the Gate is high (positive volts) the switch will make, connecting Source and Drain.
The resistor keeps the Gate low until you touch the contacts. As long as your skin has less resistance than the 4.7meg resistor then it will turn on.
Hope that helps.
Finally able to access the drawing - so, the +5 would be battery positive, and the grounds would be battery negative for our use, correct?
Of course, we'd have to use a MOSFET with a heavier rating than a ZVNL110A... and I think I found one: STS6NF20V
Datasheet link - what do y'all think?
Added: looks like the IRF510 from Ratshack would work, as well, power-wise.
Of course, we'd have to use a MOSFET with a heavier rating than a ZVNL110A... and I think I found one: STS6NF20V
Datasheet link - what do y'all think?
Added: looks like the IRF510 from Ratshack would work, as well, power-wise.
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Yes, the ground is negative
The STS device looks excellent for the job. The IRF510 has a high gate voltage so wouldn't be reliable.
I put my IRL2505 board in a box with an 18650 and that is running fine but its a bit bulky for a smaller rig. The contacts are just pieces of tin cut from a sheet.
A bit of hacking around with an old project box from a local electronic bits supplier - I'll have to find a better housing for a more professional looking version:
The STS device looks excellent for the job. The IRF510 has a high gate voltage so wouldn't be reliable.
I put my IRL2505 board in a box with an 18650 and that is running fine but its a bit bulky for a smaller rig. The contacts are just pieces of tin cut from a sheet.
A bit of hacking around with an old project box from a local electronic bits supplier - I'll have to find a better housing for a more professional looking version:
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Ok what about these 19mm stainless steel active metal switches here:
ActiveMetal Switch Sensors
Datasheet:
http://www.itwactivetouch.com/pdf/AM_SFCatalog.pdf
Not sure if these have been covered.
Dan
ActiveMetal Switch Sensors
Datasheet:
http://www.itwactivetouch.com/pdf/AM_SFCatalog.pdf
Not sure if these have been covered.
Dan
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