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Breaktru Forum  |  eCigarette Forum  |  Modding  |  Topic: Undervoltage Voltage Protection for a Mosfet Box mod
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Author Topic: Undervoltage Voltage Protection for a Mosfet Box mod  (Read 5239 times)

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Offline Zanderist

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Undervoltage Voltage Protection for a Mosfet Box mod
« on: February 05, 2015, 10:23:28 PM »
I was thinking of an idea to try out involving a way to stop a mosfet from firing when the voltage drops to certian point using discrete components. I have already posted this on another site but, seems that no one may know anything. I'm asking here cause it appears to have pretty knowledgeable people here.




What's going on in this circuit is that I have 3 switches in series with the gate of the mosfet. Also to point out the parts in this drawing are not going to be the parts choosen just there to make the drawing.

Back to the 3 switches, one of them is a transistor acting like a switch that turns on when a zener diode connected in reverse has a voltage greater than 3.3 connected at its cathode.

That diode after the transistor is to add a known voltage drop to make sure no small voltages that may leak through would still partially turn on the mosfet.

Finally there's an LED connected to the circuit in order to tell if the circuit is operating anymore.

Question is, could like this work?
could I use a voltage divider at the base pin as a replacement to the zener diode?

I understand though I could just opt for a low battery indicator circuit, but I'm trying to reduce the number of parts used.
« Last Edit: February 06, 2015, 12:41:15 PM by Zanderist »

Offline CraigHB

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Re: Undervoltage Voltage Protection for a Mosfet Box mod
« Reply #1 on: February 06, 2015, 11:48:55 AM »
Your diagram is not showing up, but the easiest thing to do is use a voltage detector to drive a MOSFET.  I would suggest this one;

http://www.ti.com/product/tps3700

It has a detection range down to 400mV with no upper limit and a power supply range from 1.8 to 18V.  Wiring the part only requires a resistor divider for the detection threshold and a pull-up resistor for the output.  Doesn't get much more simple than that.  You can put it in series with the trigger switch so the MOSFET does double duty, no need to drive a separate MOSFET with it.


Offline Zanderist

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Re: Undervoltage Voltage Protection for a Mosfet Box mod
« Reply #2 on: February 06, 2015, 12:45:00 PM »
Well I might just do that now.

I've fixed the diagram.

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