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Forum Index : Microcontroller and PC projects : 24 volt relays powered while MM boots
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bigmik Guru  Joined: 20/06/2011 Location: AustraliaPosts: 2914 |
I am wondering why they are pulled HIGH in the first place? I admit, I dont have much (read any) experience with MOSFETs but translating into PNP/NPN transistor terminology I would think that pulled LOW would be what you would want, providing you set the pins as DIGITAL out as you have mentioned you have. Great effort and a great project, well worth adding to TBS forums, I think you should publish your design somewhere. Regards, Mick Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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centrex Guru Joined: 13/11/2011 Location: AustraliaPosts: 320 |
The circuit that Peter has used is from the original maximite articles in Silicon Chip. He has had a steep learning curve, the water heater he has built himself. Cliff Cliff |
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pcaffalldavis Senior Member  Joined: 17/10/2011 Location: United StatesPosts: 187 |
I got the failsafe shut down "break the copper wire link" GOSUB routine added to the program today. Now if the boiler water temp ever gets up to or above 95 C the Air intake motor will turn for five seconds pulling away from the Air intake plate breaking the copper link. This allows the air intake plate to fall back and shut off the air flow to the firebox. I also added a test for this feature to the "hidden" TECH MENU so I can trick the MM into thinking the boiler water temp is too high and watch it do the failsafe shutdown routine. I tested it today. It works great. I also have it display 'TEND TO FIRE' and the program won't attempt to restart the fire again until it is done manually. 'Course you have to reconnect the copper link each time too. MUCH safer! I'm busy finishing my wifes kitchen (after she patiently waited for 9 years) so I won't get a chance to jumper the 10k resistors to ground instead of 5 volts for a few days. I'll report back on this later. I will share the full design, details and program, but not until after at least one season of real world testing. I would not want to share a design that might do something potentially dangerous, like the rogue reboot that left the air intake open while the MM thought it was closed a couple days ago. Oh, another good thing to report to those who may recall from my earlier posts. The firebox design is of the "new" stainless steel air intake tube type combustion design where the air intake tubes run across the top of the combustion chamber. I was hoping it would burn cleaner than a typical wood-fired boiler and boy it does. With the help of a recycled truck squirrel cage heater blower installed as a fire box blower, it fires up from a light whispy stream of smoke to a blazing hot almost invisible plume of hot gasses in about two minutes. I'm talking about how it appears at the top of the chimney. I have a security camera focused down on the chimney from the 3rd floor. This thing burns CLEAN and when the fire is shut down (about 80+% of the time) there is only a small steady whispy exhaust of smoke. This clean burning aspect is already a resounding success. All wood burners should incorporate this upper fire box air tube design. It burns very clean with or without the blower. I just use the blower 'cause it gets up to temp faster. Thank you everyone! We're all here 'cause we're not all there. |
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| centrex Guru Joined: 13/11/2011 Location: AustraliaPosts: 320 |
Hi Pete Did you ever overcome your relay problems with the boiler. Regards Cliff Cliff |
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