Hi all, I am working on a Engine - compressor based crawler machine. having 24v DC system. One microcontroller is used on the m/c for measurement of revolutions of gear motor. Problem:- Due to some 10-12 solenoid valves are also operated from the same 24V DC source facing a problem of surges causing failure of controller. we tried to use diodes & capacitor combination across each solenoid to suppress surges still the problem persist.
Please advise what modification can be done.
Maybe a Varisitor? Is the power supply to the microcontrollers regulated?
A quick search in google returned
To suppress a coil operated from dc, a reverse diode across the coil with no capacitor is usually all that is required.
When faced with this type of problem the whole system needs to be reviewed for ways that the noise is getting to the ucontroller. including wire routing, location of parts, filtering of power supply, filtering on the ucontroller board, filtering of incoming and outgoing signals, grounding etc. - this often takes experience and detective work to solve. (Solving these problems is one way to gain experience)
Dan
-- Dan Hollands 1120 S Creek Dr Webster NY 14580 585-872-2606 dan.hollands@gmail.com www.QuickScoreRace.com
I barely know where to start. You've clearly got yourselves into a mess through a failure to understand basic good design practice.
You probably have EMI problems - maybe also 'dirty grounds'. Without a detailed knowledge of the product it's hard to say.
As the Irish would say " If I wanted to get there, I wouldn't start from here " !
Graham
Yes.
In short you need an expert. Something that was likely missing from the original design team.
Graham
It might be sags, not surges, if those solenoids draw a lot of current. You could feed the 24V through a diode to a big cap on the input of the voltage regulator that powers the controller. When the solenoids operate, they can't suck the charge off the cap due to the diode, so the controller Vcc won't see the sag, if it exists.
Ed
It could be *almost anything* given the vagueness of the OP's post.
One would hope that they have at least used clamp diodes across the solenoid coils.
I think we can safely assume that his uC isn't powered directly from the 24V though. Since it'll be powered by some voltage regulator somewhere a good question would be to enquire if the regulation is/isn't local and.or whether it shares any current paths with the load(s) - look for 'ground noise'.
I'd also look very closely at trace loop areas to see if there's some electromagnetic coupling between the solenoids' magnetic fields and the uC inputs.
Graham
Separate the power leads at the battery, so that the solenoids and the uP regulator have separate power/ground loops; optoisolate the processor; ideally, use a separate battery for the uP.
Good Luck! Rich
solenoid to
You mean like this product?
This product looks expensive. But by using an extra isolated battery just for the controller would be much more cost effective. The question is how to separate the two power source once the 10-12 solenoid valves begin to operate? I have about the same dilemma as the OP for my car alarm that goes off during driving when it's on the same battery as the car.
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