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Ive almost finished Xen now, and have been giving it a test run. Everything runs fine until I use the saw at the back, then the signal is lost. The problem is its run off a starter motor trigger by a solenoid. Unfortunatly, my attempts to get into the thing to clean it have been unsuccessful as the bolts refuse to budge. Admittedly, I havent fitted ANY suppression yet, although i will be doing tonight (will a 10,000pf capacitor across the terminals do it?) How do i suppress the spark inside the solenoid? and any other tips? All my sensative electronics are inside aluminium boxes.
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EMI !!!
btw, the starter motor is completely isolated from the shell and chassis as it is mounted on a non-electically-conductive material, and also how do I supress relay contacts too?
Many thanks in advance -
EMI !!!
http://www.technobots.co.uk/Technical/Guidance/EMI%20and%20how%20to%20deal%20with%20it.pdfhttp://www.technobots.co.uk/Technica...o%20deal%20wit h%20it.pdf
Try that.Comment
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EMI !!!
Cheers Ian
Ive also noticed that the supply to my electronic equiptment drops a bit when large motors are switched on. Could I use a capacitor across the supply terminals to my electronics to help relieve this problem, and if so what type and how big?
MattComment
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EMI !!!
Whats the problem, a relay not changing over? Generally what people do is put a 4.8volt receiver battery inline so as to up the voltage for the relay. THe will only need to be charged once in a blue moon.Comment
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EMI !!!
nope, the onboard computer crashes. It works fine up until i use the saw, so Im presuming the problem is due to either a supply voltage drop when running the saw or interference from it. Im planning to suppress all motors, solenoids and relays and fix the supply drop problem (although the supply does go through a regulator anyway) and hopefully that should sort it
Comment
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EMI !!!
http://homepages.which.net/~paul.hills/Emc/Emc.htmlhttp://homepages.which.net/~paul.hills/Emc/Emc.html
might be of helpComment
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EMI !!!
It might be worth a try to put in about 4.8volts extra. It may just solve that problem.Comment
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EMI !!!
hmm, maybe but i dont want to risk blowing the DC-DC that runs the PC.Comment
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EMI !!!
Heres an idea, i dont know how practical it is but I am assuming the computer requires little juice. WOuld it be possible to give it its own battery supply?Comment
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EMI !!!
yeh, the computer uses less than 50watts as theres no mechanical parts besides the cooling fan (which is connected directly to the battery anyway)... all drives etc are solid-state. Ill give it a go on its own seperate battery and see if it is just the voltage drop thats the problem, and if so ill try a capacitor across the supply to sort of even it out.Comment
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EMI !!!
The problem will be conducted interference. The large surge of current required by the starter motor causing the computers supply to disappear monetarily.
What fixes these problems nearly 100% of the time is to run your power (motors & weapons) on a separate battery entirtely to the control and radoi electronics. The electronics then controls the power stuff via opto-isolators. NEVER connect the two together electrically - they must be isolated.
This has been the solution to numerous people who have emailed me for help with this kind of problem. My site that gary cairns pointed to above contains information on how to achieve this, with links to sections on optoisolators.
Good luck!Comment
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EMI !!!
cheers guys...
Diodes fitted to all solenoids and relays, suppression capacitors fitted, no problems so far :S fingers crossed!Comment
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EMI !!!
btw, since the weapon motors use solenoids to trigger them and are not pulsed, could i fit extra suppression capacitors to them to provide more of a buffer? Its the starter motor im most concerned about.Comment
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EMI !!!
starter motors draw so much current that any other circuits will have its share of the battery leeched.
The best suppression for starter motors I found were the drive mechanism from a circuit breaker - if you take one apart there is a set of copper plates with air gaps - connect both motor contacts to the 2 outer plates.
Also, to diminish the amount of current the motor wants to take, allow the motor to rev in excess of 10,000rpm - by the use of gearing - and it will not only speed up very quickly but generate a lot of internal resistance, hence reducing current flow.
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