 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Microcontroller and PC projects : power?
  Page 2 of 2 |
|||||
| Author | Message | ||||
sparkey Senior Member  Joined: 15/06/2011 Location: AustraliaPosts: 819 |
so therefore you are reducing the clock speed or the frequency that the chip runs at...is the 32Kz xtal inside the chip or is it physically fitted and slowing down the chip by that much i can see why it could use less power and yes i agree hex code would have to be added/changed to give that option ...was the 32Kz xtal intrduced as an extra that geoffs does not have... technicians do it with least resistance |
||||
| Olimex Senior Member Joined: 02/10/2011 Location: BulgariaPosts: 226 |
yes, original maximite do not have 32kHz crystal and as Geoff use one of the low frequency crystal port as VGA/composite selector this crystal can't be add on maximite |
||||
pcaffalldavis Senior Member Joined: 17/10/2011 Location: United StatesPosts: 187 |
I tried running my SM1 Dontronics on a clean, accurate 6 volt bench power supply and it will not boot. I have to have at least 8 volts before it will start up. I'm confused to read that I should be running it on 6 volts. Could that be the original Maximite instead of the DonTronics SM1 version? I looked all over the DonTronics web site and the schamatic for the voltage information, and there does not seem to be a voltage listed. Isn't the SM1 designed to run on 9 to 12 volts? Pete in Hyder We're all here 'cause we're not all there. |
||||
donmck Guru  Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
Not sure what direction you are heading Pete, but I think the standard 7805 input must be about 7.5V to about 20+ Volts. read: http://en.wikipedia.org/wiki/78xx for example. The SM1 uses a 7805 on the input. If you want 5V operation, then use the USB port for power. I am confused to read you should be running it on 6VDC, as Geoff's power schematic is almost identical to Richard's. The only difference being the SM1 uses some low voltage diodes, instead of a power selection link. Hope this helps, Cheers Don... https://www.dontronics.com |
||||
| pcaffalldavis Senior Member Joined: 17/10/2011 Location: United StatesPosts: 187 |
Thanks Don, I was going by what Sparkey said in an earlier post a few back in this thread. Seems two different ideas got crossed. I only said I did my first SM1 test using a 9 volt battery as I was interested in seeing how long it would run. You, and others I think, then said it was not designed really for battery usage. I knew that, but assumed everyone was talking about small batteries. Then when Sparkey suggested a 6 volt battery I was confused again. If it would run on a six volt battery (larger one) then I figured it should run on a 6 volt clean, regulated bench supply at 6 volts. I was just noting that my SM1 does not run on 6 volts. I only asked for clarification because I plan on powering the Maximite for the boiler from a large 12 volt CAT battery. I also read that it was suggested to another American that recently joined the group to obtain a 6 volt power supply for the SM1 he is awaiting deliver on. For my wood boiler I plan to run all the 110 volt items from an inverter off this same battery. It will be charged using a 90 Watt solar panel and a high quailty 110v to 12 volt line battery charger/conditioner. That should make the entire system fool proof when the power goes out... which is at least monthly. For example we have had about 8 power outages in the last month as winter gets under way here. Granted this is a lot of outages, but I just wanted to make sure I was not planning on powering the SM1 from a source that had too much voltage. These batteries often get up to 14 volts when the charger and solar panel are contributing. Is that too much voltage do you think? Pete in Hyder We're all here 'cause we're not all there. |
||||
| donmck Guru Joined: 09/06/2011 Location: AustraliaPosts: 1313 |
That's fine Pete, I would have to chase the 7805 specs, but I think they will handle up to 35VDC, but you would be asking for trouble at that voltage I would think. If you are talking about 14VDC (13.8VDC is considered normal in a vehicle charging circuit) then this will be fine for both the Maximite standard and SM1s. Cheers Don... https://www.dontronics.com |
||||
| pcaffalldavis Senior Member Joined: 17/10/2011 Location: United StatesPosts: 187 |
Thank you Don. That is what I needed to know. I'm a bit familiar with the LM317 but didn't know about the 7805. Do now! My solar controller runs up to 14.2 actually. I think the folks that made this solar controller possibly thought would most often be used on banks of 6V (paired in series for 12 Volts) golf cart batteries. Perhaps those systems work a bit differently? Anyway, my solar panel with its controller puts out 14.2 and my 110 VAC to 12 VDC charger/conditioner puts out 13.8, just like you said! Pete in Hyder Alaska We're all here 'cause we're not all there. |
||||
TassyJim Guru Joined: 07/08/2011 Location: AustraliaPosts: 6097 |
Don, If you run the Maxi off 14V be careful about the power dissipation in the 5V regulator. (14.2-5)*0.125=1.15 Watts. This is a bit much for the on-board regulator. Either put a 5 watt 33 ohm resistor in the power lead or an external 8 volt regulator to keep the internal power dissipation under control. Running 24/7 needs a lot of de-rating for reliability. Jim VK7JH MMedit MMBasic Help |
||||
| Page 2 of 2 |
|||||
 Print this page |
