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Forum Index : Microcontroller and PC projects : MM shutting down
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| jeffj Regular Member  Joined: 04/02/2012 Location: AustraliaPosts: 81 |
Colour maximite I have a MM in my shed . Every time I switch off the fluorescent lights the MM shuts down. By a process of elimination I found that a spike is coming down the line from the VGA screen. The MM is powered from a battery. The lights and power are on separate circuits . The screen is off the power circuit. Any ideas how to fix it would be welcome. Another question related to the above . I am logging my hydroponics installation using a modified version of “DATALOG” in the library. It stores the data on the SD card with an xcel .XLS extension. I have my spare laptop connected to it and communicate into the house using wifi to my desktop. My question is :- Is there any way I can read the xls file on the desk top. I want to manipulate the data so that I can draw graphs of the variables. At the moment I take the Sd card out and physically transfer the info . As soon as I do this the program generates an error as it can’t find the SD card and stops. Regards Jeff |
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TassyJim Guru  Joined: 07/08/2011 Location: AustraliaPosts: 5950 |
You can use Xmodem to transfer the data file but while that is happening, your program will not be logging. Alternatively, if the laptop is running all the time and connected to the MM, You can print the data readings out as they are ready and have the laptop store them. This should allow you to play with the data without interrupting the main acquisition program. That is the method I used to use. To reduce the interference issues, I would start with plenty of clip-on suppressors on all the leads. Jim VK7JH MMedit  MMBasic Help |
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Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3169 |
Almost certainly the resets are caused the capacitor connected to the Vcap pin of the PIC32. See the Maximite FAQ for more details (http://geoffg.net/MaximiteFAQ.html). Geoff Geoff Graham - http://geoffg.net |
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| jeffj Regular Member Joined: 04/02/2012 Location: AustraliaPosts: 81 |
Thanks for your comments Jim and Geoff. I tried a 275V MOV across the lighting circuit and then it only shut down now and again . I had a look at the caps. I already had 2 tantalums connected due to a previous problem you helped me with. I put a surge suppressor on the power supply to the screen and that fixed it. Thanks again. Fantastic forum. Jeff |
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redrok Senior Member  Joined: 15/09/2014 Location: United StatesPosts: 209 |
Hi Jeff;MOVs can sum times help but a better choice is to put a high voltage capacitor across the line. MOVs are not capacitors. They work by snubbing the voltage spikes which exceed their breakdown voltage. But there was still a voltage spike. A capacitor is always leveling out voltage spikes, even small ones. Sure, it's nice to have the MOV to prevent damage when a really big spike occurs but also have a capacitor across the line to prevent the noise. redrok |
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| jeffj Regular Member Joined: 04/02/2012 Location: AustraliaPosts: 81 |
Thanks Redrock I thought I had fixed it but still had occasional trips I connected an MOV across the switch and it was much better. I am going to have another go and try some snubbers as you say, They probably attack the fast rising spikes better or perhaps earlier. Jeff |
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| twofingers Guru Joined: 02/06/2014 Location: GermanyPosts: 1148 |
@Jeff Maybe you should replace your fluorescent lamps (inductive ballast) with some using a electronic ballast. Lamps with a inductive ballast destroyed in my house a lamp with a electronic ballast. Two times.  |
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| jeffj Regular Member Joined: 04/02/2012 Location: AustraliaPosts: 81 |
Fixed ! I connected a 275v 0.1 uF cap + 100ohm series resistor across the lighting cicuit at the distribution board. I left the Movs in . No further trips |
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| skylight Newbie  Joined: 10/01/2016 Location: United KingdomPosts: 23 |
@jeffj Usually the cap is placed within the fluorescent fitting across the input terminals which keeps it close to the ballast, I'm not so sure I'd want the energy from a high voltage spike running through the house lighting wiring as would happen with your setup with the cap at the dist board/consumer unit. Also I believe it may be an offence in your country modifying the electrics to a non standard form from reading other posts? Of course that comment assumes a non qualified mod and apologies if this is not the case. |
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| jimbotron Regular Member Joined: 27/11/2013 Location: AustraliaPosts: 46 |
Try putting some low value resistors (try 10 ohms) in series with the H-sync and V-Sync lines. These are attached directly to the MCU and without buffering the inbuilt clamping circuits on the chip might not be able to protect the power lines from the spikes. I had a similar problem with a motor speed controller feeding spikes via a mosfet to an output pin. I blew up a few devices before putting the resistor in. |
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| jeffj Regular Member Joined: 04/02/2012 Location: AustraliaPosts: 81 |
Thanks for yr comments. I connected the cap and resistor across the lighting circuit at the Sub distribution board in the garage not the house . I have not had a trip since. |
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