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Post by Deleted on Aug 30, 2008 19:06:16 GMT -8
A large solid copper CPU heat sink with fins makes a perfect heat sink for your PWM Mosfet chip. It even has a place for a fan on it. Don't skimp on the fan....buy a new one! Make sure your chip comes with an installation kit (mica insulator, screw w/it's insulator and a tube of Joint Compound.)
On mine I drilled and tapped four mounting holes around the face of the heat sink and one in the center for the chip. Be sure you deburr that hole so the chip makes good contact. Make a big hole in the pc board cabinet for the chip to slip down into when you mount the heat sink to it. Good luck, Ron.
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Post by Gary Lecomte on Aug 31, 2008 5:04:02 GMT -8
Another Tip:
If your using the PWM for generating HHO:
"Do NOT place your heatsink in the motor compartment".
The "Ambient temperature" in there is far to hot to allow the heatsink to cool properly. ESPECIALLY so, in a Warm Summer.
Also, Ideally your Heatsink should be mounted External to the Box that contains your electrionics. Mounted in FREE Air.
Gary
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Post by gracie on Sept 1, 2008 9:20:53 GMT -8
I also have a PWM, it's a Bactronics, so far I have good control. When startup the gen operates at 13V & 15amp. as it warms up I turn the PWM constantly to keep the amps at 15. The volts drop to 10 volts at about 50 miles. I did realize 8mg increace on the first 2 tanks (10gal) I think that I need to experiment with the oxy senser. This is a Smack II installed in a 1989 Toyota 2-wd pickup. I installed a v-meter & a amp-meter with the PWM, all is mounted in my dash for good control. I have an electric temp gauge comming that will mount in my dash for better control of the gen. I don't know at what temp will be the best without experimenting. (as we are all doing)
Can anyone reccomend a control for the oxy senser? This pickup has a 22re engine (efi) that is with a throttle body. Didn't think the oxy senser would be affected, but I think I should get a lot better mpg.
Gen was putting out 1 1/2 ltpm on the bench. thanks for any help---
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Post by Deleted on Sept 10, 2008 19:29:24 GMT -8
Before you spend big bucks for an efie, check out "dmbing" s articles on youtube. Thanks for post, Ron.
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Post by Deleted on Sept 19, 2008 15:02:37 GMT -8
Hi. I've since abandoned the afformentioned setup and have gone to the following; large heatsink out of an Apple computer, cut down to 3x3 inches. affixed to this is a "Super Fan" (my jargon) This is one of the Orange fans used on high performance IBM game machines. This thing is a friggin air pump. Comes with a thermistor that when affixed to the heatsink, provides whatever air you need. I ran my hho generator with it at 20 amps today for a couple of hours, mosfet (064) stayed just warm to the touch. Costly but with dual ball bearings and an estimated 50,000 hours usability, maybe cheap by comparison. More later, thanks, Ron.
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Post by Deleted on Sept 20, 2008 4:35:23 GMT -8
Finished the "Zero" PWM today. Only mod I did was to lengthed the .003 ohm resistor (R12). This allowed me to, when I wish, to plug in a 0-50ua meter and read current (meter now says 0-50 amps). The thing works great. Thanks for the help Gary! Now gotta start on the Efie..........
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Post by Gary Lecomte on Sept 20, 2008 6:23:17 GMT -8
Finished the "Zero" PWM today. Only mod I did was to lengthed the .003 ohm resistor (R12). This allowed me to, when I wish, to plug in a 0-50ua meter and read current (meter now says 0-50 amps). The thing works great. Thanks for the help Gary! Now gotta start on the Efie.......... Lengthing R12 increases its Resistance, but it also reduces the Maximum Current capability because of the increased voltage output into U1d. Probably you Can't get to 50 Amps now. R10 & R11 create a Gain of about 1000 in U1d. Depending on How Much you increased "R12's resistance", you could now SOMEWHAT "Decrease the Resistance of R11", to offset the increase in R12, so as to get back that lost current control. (EXAMPLE: If you Doubled R12's Resistance, Half the Resistance of R11.) Although this circuit works better than just normal PWM to control the current, it is NOT Very Efficient when it goes into the current foldback mode. This winter, Assuming I can get some SPARE TIME, I plan to create a much more efficient design to control these currents. Gary |
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