View Full Version : alternative to pwm maybe?
alpha-dog
12-30-2008, 11:24 PM
(-)+NNNN+(partition)+NNNN(-)+
1049
imagine C1 and C2 as the two cells above
Q-Hack!
12-31-2008, 02:28 PM
(-)+NNNN+(partition)+NNNN(-)+
1049
imagine C1 and C2 as the two cells above
It has been a while since my electronics school, but that looks like a monostable vibrator.
alpha-dog
12-31-2008, 04:42 PM
I think your right. Actually more like an A-stable multivibrator. But doesn't it look like it would work.
I built the test cell today for it. The partition is plastic with no water hole at the bottom, just gas at the top. I'm going to run it straight dc this weekend and monday I'll bring it to work with water in it to measure capacitance.
Q-Hack!
01-01-2009, 05:03 AM
Most of those that I have ever seen were designed for low current purposes and only generating 1V Peak to Peak. You see them mostly in TTL logic circuitry.
alpha-dog
01-01-2009, 01:09 PM
Most of those that I have ever seen were designed for low current purposes and only generating 1V Peak to Peak. You see them mostly in TTL logic circuitry.
This came from a design to convert 12vdc ( car battery ) to 120vac. Its rated at 30 amps. I took the transformer off and substituted a center tap inductor ( I'll be making ). RC time will be important here as I want to keep it slow so I'll have to measure the capacitance of the cell blocks in the generator ( RC =T ). I'm hoping for a usable capacitance, otherwise I'll have to add a switch plate capacitor in parallel to it to make it work.
Q-Hack!
01-02-2009, 06:57 PM
You wont get a stable capacitance reading from your HHO generators. As the generator heats up the capacitance values change. This is the big problem when designing around them.
Yes, changing the value of C1 and C2 will change the speed that the A-Stable vibrator turns on and off. However it will always turn on and off at the same pulse width. In order for your cell to maintain heat levels, you need to be able to change the time on differently to the time off. In other words, the A-stable multi-vibrator will always be at 50% duty cycle.
Anybody else see this differently?
alpha-dog
01-02-2009, 10:32 PM
What problems do you see with 50% duty cycle. I am trying to reduce current draw without loosing very much HHO production. I'm feeling that 50% pulse width and maybe .5 sec duty cycle would be good. My test generator continues to produce HHO maybe 1 minute or longer after I remove the input power.
Q-Hack!
01-03-2009, 03:04 AM
What problems do you see with 50% duty cycle. I am trying to reduce current draw without loosing very much HHO production. I'm feeling that 50% pulse width and maybe .5 sec duty cycle would be good. My test generator continues to produce HHO maybe 1 minute or longer after I remove the input power.
Is it still producing or just releasing the bubbles out of solution? If you stop applying electricity you should not be producing any HHO. Also, I think you have your terminology backwards... duty cycle is expressed in percentages and pulse width is expressed in time. So it should read:
"I'm feeling that .5 sec pulse width and maybe 50% duty cycle would be good."
and to answer that: Yes, it would be good if that is the duty cycle that keeps you from over heating while maintaining your efficiency. However, chances are that the duty cycle you need for maximum efficiency will be something different.
I highly recommend reading the thread http://www.hhoforums.com/showthread.php?t=917 ridelong has designed a PWM which allows your generator to use less current as it heats up. It starts out close to 100% duty cycle and lowers as it gets warmer. If you decide to go this route, you will want to read the entire thread as he makes and corrects a mistake in his first design. But overall it does what you are trying to do. No sense trying to reinvent the wheel here. :)
alpha-dog
01-03-2009, 05:07 PM
When I do test in my garage the generator has produced gas for maybe 2 or 2.5 minute. I read voltage across the cell and it will be 5.5v so there is a charge. I want to take advantage of that if possible. Thank for pointing out my mistake of duty cycle.
My generator is not heating up. It is using to many amps for the amount of gas I think I need. Another guy I've been in touch with and uses the Hemi engine didn't get good results until he began producing 5.5Lpm. Using 10~15 amps per cell block to get 1Lpm I would need at least 6 cell blocks. At 60 to 90 amps its just crazy. His solution was getting a bigger alternator.
alpha-dog
01-05-2009, 05:54 PM
My test generator measures:
Accross cell block ( +NNNN- ) = 974uf
leakages = 88.8ma
The capacitance is great but the leakage is not. It looks more like a battery.
Q-Hack!
01-05-2009, 07:38 PM
My test generator measures:
Accross cell block ( +NNNN- ) = 974uf
leakages = 88.8ma
The capacitance is great but the leakage is not. It looks more like a battery.
That sounds about correct. Remember that the HHO generator contains what is essentially a conductive liquid. A true capacitor will have a dielectric that doesn't conduct electricity. Because of this you will have a very leaky capacitor.
NOTE: If you have two different metals in the HHO generator then it may act like a battery. Think penny and nail in a lemon trick.