Breaktru Forum
eCigarette Forum => Modding => Topic started by: Learfx on March 16, 2013, 02:13:38 PM
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I have a chip that came out of a clearomax mod. I am trying to use it in a copper mod using the STD30PF03L MOSFET. http://www.datasheetcatalog.org/datasheet/stmicroelectronics/8817.pdf (http://www.datasheetcatalog.org/datasheet/stmicroelectronics/8817.pdf) I am trying to set it up as a touch switch. I have it wired up as shown in the first picture but it will not function. The display will come on for a bout 2 seconds and then turns off. The voltage on the the tac switch is not full voltage from the battery. Looking at the first picture the voltage comes in on the left side. It reads around 3.2 to 3.3 volts. Looking at the second picture, jumping a wire across the tac switch will allow it to operate normally. Is it possible that the mosfet may not work properly with lower voltages? I'm not an engineer so looking at and understanding the data sheet is a little tough.
(http://learfx.com/tmp/pmos1.png)
(http://learfx.com/tmp/Jumper.png)
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That data sheet has no data :) Really, one of the crappiest data sheets I've ever seen. There's only a lower limit for the gate-source threshold voltage and no chart for the on resistance versus gate-source voltage, or any charts at all for that matter. So, hard to say, but crappy MOSFETs like that usually need at least 4V to turn on fully. There's much better "logic level" MOSFETs out there that will fully turn on with gate-source voltages as low as 2.5V.
You don't need a power MOSFET either. A small signal MOSFET will work fine for that since only small currents are involved.
A 100 meg resistor is really high. If the MOSFET is leaky, which I'm sure it is, the leakage can pull down the gate voltage enough to cause the transistor to start conducting. Also, with a P-Channel, you need to verify the pull-up resistor and source are in fact connected to the positive side of the switch.
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What I deduced from looking at a VMax controller board. The left side of the tact has 3.3v VCC on it. The right side is a controller input.
Closing the tact switch turns the input from Low to High.
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I know when I put a voltmeter across the tac switch from left to right, It goes from 3.3 to 0 volts when I press the switch. I guess I'm SOL without more information on the vmax controller board.... :wallbash: Could I get away with using a small tac switch extended off of the tac switch that's on the board now? http://www.madvapes.com/tactile-switch-with-round-actuator-300g.html (http://www.madvapes.com/tactile-switch-with-round-actuator-300g.html) Thanks for the replies. ;bow;
(http://learfx.com/tmp/tac.png)
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Sure you can.
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Thanks again for the help and support. Gonna finish this mod up in a couple of days and post pictures soon. :thumbsup:
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Thanks again for the help and support. Gonna finish this mod up in a couple of days and post pictures soon. :thumbsup:
We will be waiting :popcorn:
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Finished this mod yesterday, I call it the "Copper Max". I couldn't use the touch switch with it so used a remote tac switch instead. I used pvc pipe as a cradle for the z-max controller board. I used the housing of the clearmax to cut a window for the display screen. The mod is fully functional and can use flat top or button type 18650 batteries. I was wondering if these chips can handle the voltage from 2- 18350 batteries? If so then this mod can use those battery types as well, along with cr 123's. I'll post more pics on my site @ learfx.com in a day or so. Thanks again for the help guys.
(http://learfx.com/tmp/cm1.JPG) (http://learfx.com/tmp/cm2.JPG)
(http://learfx.com/tmp/cm3.JPG) (http://learfx.com/tmp/cm4.JPG)
(http://learfx.com/tmp/cm5.JPG) (http://learfx.com/tmp/cm6.JPG) (http://learfx.com/tmp/cm7.JPG)
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Fantastic workmanship :rockin smiley: Great and unique
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Nice looking mod. The design work is really sweet. Great job!
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nice job LearFx how hard is it to do that etching on the copper? just wondering what the brass part on the top cap is from? :beer-toast:
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That data sheet has no data :) Really, one of the crappiest data sheets I've ever seen. There's only a lower limit for the gate-source threshold voltage and no chart for the on resistance versus gate-source voltage, or any charts at all for that matter. So, hard to say, but crappy MOSFETs like that usually need at least 4V to turn on fully. There's much better "logic level" MOSFETs out there that will fully turn on with gate-source voltages as low as 2.5V.
You don't need a power MOSFET either. A small signal MOSFET will work fine for that since only small currents are involved.
A 100 meg resistor is really high. If the MOSFET is leaky, which I'm sure it is, the leakage can pull down the gate voltage enough to cause the transistor to start conducting. Also, with a P-Channel, you need to verify the pull-up resistor and source are in fact connected to the positive side of the switch.
Thanks for the information Craig. I decided to just use a tac switch in place of the touch switch. I have used that particular mosfet in the past without issues. If there is something better then I would love to know about it. What p-channel mosfet would you recommend for the Ti PTR08100WVD or Ti PTN04050CAH ? I don't have extensive knowledge in electronics but I've learned so much reading the forums and building mods. Thanks again for the reply ;bow;
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nice job LearFx how hard is it to do that etching on the copper? just wondering what the brass part on the top cap is from? :beer-toast:
Thanks fsors The etching is really the easy part. Getting the design to stick to the copper is the tricky part. It takes a lot of Patience and some trial and error to get a good image for etching. Even then the results are never perfect. It's basically the same idea as etching a circuit board but instead of a flat board you're using a round tube. The brass part on the top of the copper is a type of compression fitting used in sinks and lavatory faucets for the hot and cold water supply. I don't know what they're official named but we used to call them "Pecker Heads" when I worked as a plumber years back. I'm actually out of them and need to get more.
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Thanks fsors The etching is really the easy part. Getting the design to stick to the copper is the tricky part. It takes a lot of Patience and some trial and error to get a good image for etching. Even then the results are never perfect. It's basically the same idea as etching a circuit board but instead of a flat board you're using a round tube. The brass part on the top of the copper is a type of compression fitting used in sinks and lavatory faucets for the hot and cold water supply. I don't know what they're official named but we used to call them "Pecker Heads" when I worked as a plumber years back. I'm actually out of them and need to get more.
Love the way you etched this one! Can you recommend a good vid or tutorial on the process?
Think the hardware stores might stock some of the PeckerHeads? Are the PeckersHeads heavy or light in weight? Like the way it looks. Can you screw a tank or an ego mega carto in that? Is the actual connector recessed in the PeckerHead?