shopping cart empty
WORLDWIDE FREE SHIPPING
5-pack

Great little MOSFET PWM controller.
Login to post a new topic and to write a reply.
Thread Tools Rate This Thread


Search within thread:

Login to rate this thread.
#31 (permalink)      8/12/2015 2:10:21 PM US Central   quote/reply + tips
JPBel
Member
  • JoinedAug 2014
  • Posts 3620
  • Reviews 80
  • Kudos1955
@NurseJ.
The output will be about the same as the input signal.
If it is chopped, you will not have the full battery power.



Something to consider if you want a variable output.

-PWM-ing a mosfet gate make it be in its ohmic region more often, resulting in more heat generated in the mosfet, the higher the frequency the more impact it will have.

-The resistance value used to turn off the mosfet also have an effect on the heat generated in the mosfet when it is PWM-ed.
A too high value will make the mosfet stay in its ohmic region for longer at each cycles, if it even have the time to turn off.
The mosfet turn off resistance can actually be used to smooth out the gate voltage as it is basicaly creating a rc filter with the gate capacitance, depending on the mosfet, a small additional capacitor might be require to do this.
For fast switching, the capacitance at the gate need to be as small as possible, selecting the right mosfet for the job is a must.
A too low value will drain a lot of current just to turn the mosfet on, affecting the voltage at the gate too.
#32 (permalink)      8/12/2015 2:14:51 PM US Central   quote/reply + tips
hexxed
Member
  • JoinedNov 2014
  • Posts 70
  • Reviews 6
  • Kudos24
That's the whole idea/point of this, but when it's set to blue, it just outputs a constant voltage signal, so it's bascially unregulated, mechlike, with lower resistance than a mech if you use decent wire and a good MOSFET.

When set to purple, it's off 20% of the time, so you get 80% of the wattage you would when using a mech.

When set to red, it's off about 40% of the time, so you get 60% of the wattage you would when using a mech.

It's a simple way to turn down the power of your mod, I usually start at red, when it feels weak turn it to purple, then when that's weak turn it to blue, lets me get a more consistent vape even as the batteries drain.

(These percentages are fully guessed, I'm waiting for a friend to test them and give real numbers)

The PWM (switching) goes battery voltage, off, battery voltage, off, battery voltage, off, etc. That's how pretty much all DC regulation works, regulating the width of the pulses (the ratio between off and on). Yes the average voltage output is lower at red and purple settings, but that's the reason I used this board in the first place!

The MOSFET means you can run dozens of amps, rather than the 2.5 amps this board is limited to normally.
#33 (permalink)      8/12/2015 2:18:28 PM US Central   quote/reply + tips
hexxed
Member
  • JoinedNov 2014
  • Posts 70
  • Reviews 6
  • Kudos24
JPBel wrote:

@NurseJ.
The output will be about the same as the input signal.
If it is chopped, you will not have the full battery power.



Something to consider if you want a variable output.

-PWM-ing a mosfet gate make it be in its ohmic region more often, resulting in more heat generated in the mosfet, the higher the frequency the more impact it will have.

-The resistance value used to turn off the mosfet also have an effect on the heat generated in the mosfet when it is PWM-ed.
A too high value will make the mosfet stay in its ohmic region for longer at each cycles, if it even have the time to turn off.
The mosfet turn off resistance can actually be used to smooth out the gate voltage as it is basicaly creating a rc filter with the gate capacitance, depending on the mosfet, a small additional capacitor might be require to do this.
For fast switching, the capacitance at the gate need to be as small as possible, selecting the right mosfet for the job is a must.
A too low value will drain a lot of current just to turn the mosfet on, affecting the voltage at the gate too.



Well said, that's the reason I used a 6K7 resistor for the drain in order to bring the gate voltage down quicker between pulses, although by no means am I an engineer so it may well be too high still with the high gate capacitance, 18800pF, of the MOSFET I'm using, the Vishay SUM110N04-2m1P. What do you reckon?

#34 (permalink)      8/12/2015 4:42:50 PM US Central   quote/reply + tips
JPBel
Member
  • JoinedAug 2014
  • Posts 3620
  • Reviews 80
  • Kudos1955
+1 details
My current knowledge might not be enough to allow me to calculate the best value correctly.
Your guess is as good as mine.

It need to be low enough to discharge the gate before the next pulse, and in this case, doing so without lowering the gate voltage too much.

With a 6K resistor and the gate capacitance of a SUM110N04 any frequencies above ~1.4KHz should get pretty much smoothed out completly.

In this case the signal voltage can get as low as 2.8~3.2V.
So can't tolerate much voltage drop at the gate, 2.6V being the bare minimum if you don't want the mosfet to work in its ohmic region.
Measuring the average voltages(add a 100uF capacitor) at the gate for various resistance values will give you a rough idea of how low you can go, and just hope the output will be as sharp as the input with that resistance once the capacitor is removed.

Edited on 8/12/2015 at 4:43 PM. Reason:
#35 (permalink)      8/12/2015 9:58:23 PM US Central   quote/reply + tips
wuwei.ap
Member
  • JoinedMar 2015
  • Posts 22101
  • Reviews 266
  • Kudos42159
How much current does an eGo controller draw?

With an unregulated eGo board would it function like a mech?

I could easily do away with PWM and the problems involved in trying to troubleshoot it. The bonuses are: low current switch, LED indicator and 5 click on/off; which is enough reason to simply use an unregulated eGo board.

Can I do it this way?
#36 (permalink)      8/13/2015 12:12:34 AM US Central   quote/reply + tips
JPBel
Member
  • JoinedAug 2014
  • Posts 3620
  • Reviews 80
  • Kudos1955
+2 details
wuwei.ap wrote:

How much current does an eGo controller draw?

With an unregulated eGo board would it function like a mech?

I could easily do away with PWM and the problems involved in trying to troubleshoot it. The bonuses are: low current switch, LED indicator and 5 click on/off; which is enough reason to simply use an unregulated eGo board.

Can I do it this way?



Ego modules usually can output up to around 1.6~2.6A at battery voltage,current will not be a problem.

Sure, will behave like a mech with a mosfet.
With 5 clic on/off and low battery voltage protection as bonuses.
No short circuit protection tho, add proper fuse(s).

If the output of the module is not PWMed the mosfet will behave as a normal switch.

#37 (permalink)      8/13/2015 12:35:27 AM US Central   quote/reply + tips
wuwei.ap
Member
  • JoinedMar 2015
  • Posts 22101
  • Reviews 266
  • Kudos42159
+1 details
Thanks, that's good thinking about the fuse. :)

It wouldn't be much current at all when triggering the gate would it?

All these boards AFAIK have a vape time limit as well. X6's is 10 seconds.
#38 (permalink)      8/13/2015 12:38:42 PM US Central   quote/reply + tips
hexxed
Member
  • JoinedNov 2014
  • Posts 70
  • Reviews 6
  • Kudos24
+1 details
Yeah the time limit can be handy or annoying, but if you let go of the button at 9 seconds and immediately press it again you can vape for another 9 seconds and repeat till you set fire to your wick :D
#39 (permalink)      8/13/2015 3:05:19 PM US Central   quote/reply + tips
JPBel
Member
  • JoinedAug 2014
  • Posts 3620
  • Reviews 80
  • Kudos1955
wuwei.ap wrote:


It wouldn't be much current at all when triggering the gate would it?


Depend if the mosfet is voltage or current driven.

The popular IRLB3034 and the vishay SUM110N04 are both voltage driven.
Almost no current is require, just the charges to fill the tiny capacitance at the gate is needed.
~360 nanocoulomb for the SUM110N04 and ~162nC for the IRLB3034.

#40 (permalink)      8/14/2015 3:01:38 AM US Central   quote/reply + tips
wuwei.ap
Member
  • JoinedMar 2015
  • Posts 22101
  • Reviews 266
  • Kudos42159
I had the IRLB3034PBF in mind as well since it works. I assume R1 can be 15K since we are back to unregulated voltage. I found fuses for 9.5A as well, 2 x RGEF500 wired in parallel or if my battery specs change, the RGEF series of PTC seem a good starting point for me.

What I am finding, in my case, is using what is available.


The eGo T boards won't let you escape the 10 sec vape time limit by de-pressing at 9 seconds. :P
#41 (permalink)      6/3/2016 5:31:22 AM US Central   quote/reply + tips
domejunky
Member
  • JoinedNov 2015
  • Posts 5
  • Reviews 5
  • Kudos2
These are great little controllers. Looks like they changed a few things. Need to switch pin 2 to ground for external switching now, rather than pin 3.

https://youtu.be/F9lVxpVEyH4