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Bob
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« on: January 20, 2009, 06:40:28 pm » |
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If you have any PWM plans that you'd like to share with the members, Please feel free to do so here...
also if you've Made a PWM... feel free to "brag about it" here <GRIN> as its no small accomplishment! hehehe
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I'ed Like to try and collect all the info we can on PWM's ,their construction, parts use and where to obtain the needed parts and even How to properly USE a PWM in action on a vehicle.
...this will help everyone I am sure because I think eventually All of us will need to go with a PWM inorder to obtain Higher LPM's
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Bob.......
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"Mother always told me "Son the Imposable is only a little bit harder"...and You know ... She WAS RIGHT!"
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Painless
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« Reply #1 on: January 20, 2009, 08:18:59 pm » |
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I just started using an MX068 50 amp PWM on my setup, but you can't go wrong with a ZeroFossilFuel current sensing PWM. His circuit is awesome, you set the amps you want it to pull and it automatically adjusts the duty cycle to stay at that amp draw, hot or cold. http://www.alt-nrg.org/pwm-v2.html |
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Bob
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« Reply #2 on: January 21, 2009, 04:00:37 am » |
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Very Nice ! thanks for the Link Painless !
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Did you notice that in operation he said to adjust the PWM to max current and then adjust the Electrolyte to the same current ? that is defeating the purpose of a PWM !
The Idea of a PWM or at least one of the many ideas on a pwm's Use is to get the Electrolyte concentration to maximum to simply reduce the heat buildup ! less resistance in the water will make a great deal less heat... with that method that you linked you are not getting the benifit of the High electrolyte concentration and therefore will not have any less heat than usual except for a very minor drop due to the on-off pulsing of the electricity.
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better by far to simply adjust the PWM to "Minimum current", then adjust the electrolyte to maximum concentration, then adjust the PWM to the desired "Amp level"
(less than the PWM's capabilities).
...that way you get the benefit (LESS HEAT) and small increase in production of the higher concentration in the electrolyte, while still controlling the cells amperage
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I started out telling people that they needed to adjust the cell to the PWM's max output first , so they wouldn't fry the PWM, just as this guy in the link said,... but I was WRONG by doing that, because it defeats the whole purpose of a PWM in the first place... a cell ran by a PWM will indeed produce More Hydroxy gas and LESS Heat as well, but Only if its done correctly.
Yes you have to be extreamily careful not to adjust the PWM above the PWM's current handling ability or you will burn it up... but that is part of the game.
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that is how Bob Boyce and Stan Mayer both used their PWM's to allow the Max concentration of electrolyte and Keep the Current under control , that is the true goal of a PWM
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Bob......
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"Mother always told me "Son the Imposable is only a little bit harder"...and You know ... She WAS RIGHT!"
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crb
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« Reply #3 on: January 21, 2009, 11:12:00 am » |
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It's a bit of a long story why I built a PWM so I'll just cut to the chase.
I needed a fuel injector driver to drive a couple of fuel injectors.
They are kind of pricey to purchase one, so I decided to build one.
I bread boarded a 555 and a power transistor, and misc. wire, resistors and capacitors to
drive the injectors 2 of them.
A bit of a test to pulse them at the correct rate but does work quite well.
Made a huge difference in performance at WOT.
This is on my 85 mustang 5.0 auto. Now I'm trying the hho thing.
As most are experiencing, It's cold outside and I removed the unit from my vehicle.
I ordered a 1 ohm 240 watt resistor, to control my current when I put it back in
in a few weeks.
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Bob
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« Reply #4 on: January 21, 2009, 08:31:16 pm » |
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CRB:
I Love working with the 555 timer... i've made dozens of things with them and I don't think I ever burned one up !hehehehhe
they should work great in firing an injector
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Now you got me wondering what the 1ohm 240watt resister is for.... sounds like a current limiter, but what does that equate out to in limiting your amps at ?...
I havn't got that far along on figureing that out on my cell yet...
but I do think I'll use a current limiter instead of a PWM and try to run the higher octain Electrolyte ... to help keep it cool... just ain't got around to it yet !
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Bob........
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"Mother always told me "Son the Imposable is only a little bit harder"...and You know ... She WAS RIGHT!"
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crb
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« Reply #5 on: January 22, 2009, 10:03:45 am » |
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Bob,
I'm ballparking it at about 17 amps, a little low, but I'm more concerned about
thermal runaway.
I'm contemplating a dry cell design but haven't got that far yet.
The resistor was 12.95 plus shipping, Hope I can do what I want.
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Painless
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« Reply #6 on: January 22, 2009, 04:48:22 pm » |
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Did you notice that in operation he said to adjust the PWM to max current and then adjust the Electrolyte to the same current ? that is defeating the purpose of a PWM ! I agree 100%, I use maximum strength electrolyte for minimum resistance in my cell and increased efficiency. With this method I have added a whole 1 MMW to my cells rating. You'll also notice that ZFF states his PWM is only to be used off-road  I have an MX068 PWM in my truck, it's a 50 amp max model but can handle a hell of a lot more. I'm currently working on adding a current sensing circuit to it so I don't need to fiddle with duty cycle whilst driving. You can make a very simple PWM with a 555 timer chip and a few cheap parts: Connect a 10K potentiometer between Vin and dis, a 300 ohm resistor between dis and tr, short tr over to th, then connect a 3uF capacitor between th and ground. You can then use the out signal to drive a MOSFET. Russ. |
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Bob
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« Reply #8 on: January 23, 2009, 02:40:32 am » |
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Russ:
I went to the link and the Java applet thingie is empty it told me to load the Java script thing which I did and it still doesn't work
I even loaded Internet explorer, which usually runs fine with these type things and it was also just blank...
dunno whats up...
sounds interesting though , can you post a pic of it here please ?
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AHHHH never mind I got Kim to fix it fer me...seams I needed the entire Java doo-hickie and needed to turn it on too... anyway got it to work just fine!
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I was wondering how you hooked one of those up and it seams that you chose to break the ground lead with the big transisters(mosfetts)...looks reasonable to me
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however ...what is the red circle on the left going to ground ? that the ON light ?
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thank you for all the hard work as I invisioned a PWM as simple as that but never got around to making one... I don't think they have to be as complicated as most of them wind up being!
<GRIN>
now I know enough to know that the Mosfetts are picky on their saturation voltage(if that the right term) the voltage on the base that causes the other 2 legs to conduct
so the question is , what Mosfetts could be used in a gang of 4 like that that would not add up to more voltage than the 555 timers output ? sense its a fairly low voltage output
2vdc if I remember right , isn't that going to be a problem when driveing 4 Mosfetts ?
or even 2 for that matter ?
... I was thinking 4 50 amp Mosfets giving it up to 200amp capability before smokeing !
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I realise you can just drive the One Mosfett to in-turn drive many others and it looks to me that might be needed... Hope not though as its just more complications fer nuttin'
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if I build a PWM it will be like that... for sure ! thank you!
although I will probably add a led for the pulse rait adjustment(on off state) unless its so fast that its constantly on , then there is no sense to it! <GRIN>
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Thank you very MUCH !
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Bob....
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« Last Edit: January 23, 2009, 03:59:14 am by Bob »
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"Mother always told me "Son the Imposable is only a little bit harder"...and You know ... She WAS RIGHT!"
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Painless
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« Reply #9 on: January 23, 2009, 04:46:37 pm » |
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Bob, The red doohicky on the left is the 'ON' LED You would probably need to make careful choice of MOSFET's, not only in relation to the saturation voltage but the amps they are going to handle. However, you could always use the 555 to drive a transistor or smaller MOSFET that took care of supplying the switch on voltage for the main 'FET's ? Russ. |
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scratch1676
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« Reply #10 on: January 24, 2009, 08:09:09 pm » |
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cool looking java script.
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always buy a good bed and a good pair of shoes because you will always be in one of them.
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Manta
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« Reply #11 on: March 25, 2009, 11:03:47 am » |
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Just found this. Very neat; very cheap. I like it.
Bob,
The 'fan out' for the multiple mosfet arrangement shouldn't be a problem. The gate current is almost zero. The only thing to watch is that the gate voltage needs to be high enough to switch the mosfets hard on. Some need about 6 volt to do this. That is where your additional transistor driver would come in useful.
Manta
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« Last Edit: March 25, 2009, 11:24:33 am by Manta »
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Good questions have a sting in the tail.
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Bob
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« Reply #12 on: March 25, 2009, 03:32:39 pm » |
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ya forgot the URL Manta <GRIN>
hehehehehhe
wish I could say I never did that...but I can't ! HAHAHAHAH
Bob......
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"Mother always told me "Son the Imposable is only a little bit harder"...and You know ... She WAS RIGHT!"
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Manta
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« Reply #13 on: March 26, 2009, 04:29:36 am » |
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Bob, I meant I had just fount this item on the pwm plans.  Manta |
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Good questions have a sting in the tail.
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Bob
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« Reply #14 on: March 26, 2009, 04:40:02 am » |
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OOOOoooh ! ok sorry !
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Yah you should really like that plan as you can slap one togather in a few Hours Manta !
I don't think they get any easier than that do they ? HEHEHEHHEHE
( right up my alley! )
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Bob......
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"Mother always told me "Son the Imposable is only a little bit harder"...and You know ... She WAS RIGHT!"
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Painless
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« Reply #15 on: March 26, 2009, 04:27:44 pm » |
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Bob,
There is one other PWM I know of that is simpler and cheaper than that one to build... you can get it in kit form. The kit contains:
- Amp Meter
- Throw Switch
- Can of high caffeine Mountain Dew
...all you need to do is to add an easily amused Redneck and you have your very own fast switching PWM!!!
Russ.
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Bob
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« Reply #16 on: March 26, 2009, 05:02:21 pm » |
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HAHAHAHHA
But the Redneck "MUST be very easily Amused" other wise your PMW will get Bored and play with other things...and you don't want that going on under your Hood !
hehehehe
Bob.........
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"Mother always told me "Son the Imposable is only a little bit harder"...and You know ... She WAS RIGHT!"
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H²+O
Jr. Member
Posts: 86
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« Reply #17 on: September 04, 2009, 10:58:11 am » |
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Does anyone have a good set of plans for a PWM?
Painless's link isn't working anymore and I want to build a goodin! somethink like 75AMPs if i can!!!!!!
Steve out.
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