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Thread: Voltage stabilizers

  1. #1
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    Default Voltage stabilizers

    I am looking to protect screen and computer electronics from noise on the accessories power rail.

    It seems there is noise to address as the screens speaker, intended for GPS use so stereo is not bound to silence while gps is in use, has a buzz that sounds like a ground loop/ ignition noise.

    Additionally, the netbook takes a 12V supply, but I am not comfortable wiring straight up to an accessories socket that would often be nearly 13.8V

    So I am looking for something to do one of the following :
    (a) regulate/stabilize the entire 12V accessories rail.
    (b) regulate/stabilize the supply feed I am taking from the accessories rail only.
    (c) regulate/stabilize the 12V vehicle supply as a whole

    I've seen various examples of these discussed around the traps, but I don't think we have a thread here yet.

    Anyone used or installed before, and suggestions or recommendations for products?

  2. #2

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    hey,

    unfortunately my knowledge of electronics is limited, but from what you are after, i would say that you should be looking into capacitors if you want to stabilise the voltage supply to whatever component you are powering

    by setting up a few resistors, probably ones with heatsinks, you can reduce the 13.8v supply to 12 volts, and then have some decent sized capacitors which would consistently supply whatever amperage required to your device at the required voltage.

    think of the capacitors like a battery, you supply them power to charge them, then they discharge at a consistent rate as long as they are being charged at the same time, otherwise the voltage will drop over time.

    hope that helps

  3. #3
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    Yes, I've been considering the pros and cons of different approaches.
    The voltage stabilizers are a capacitor bank that handles surge loads and so reduce the battery load.
    Good example of voltage stabilizer: RAIZIN

    I may make use of one of these yet.

    However this is not going to do everything I want; I am looking at how I can create an uninterruptible auxiliary 12V power rail. This will require one maybe two small additional batteries and a battery isolator. This makes sure that the main cranking battery is not drained by the aux battery and circuit load and controls charging of the second battery.

    For this I am looking at a CTEK D250S as an all in one solution....it's an intelligent 12V 20 Amp DC/DC isolator/charger/supply.



    ---------- Post added at 07:27 PM ---------- Previous post was at 05:48 PM ----------

    Quote Originally Posted by kagerou View Post
    hey,

    unfortunately my knowledge of electronics is limited, but from what you are after, i would say that you should be looking into capacitors if you want to stabilise the voltage supply to whatever component you are powering

    by setting up a few resistors, probably ones with heatsinks, you can reduce the 13.8v supply to 12 volts, and then have some decent sized capacitors which would consistently supply whatever amperage required to your device at the required voltage.

    think of the capacitors like a battery, you supply them power to charge them, then they discharge at a consistent rate as long as they are being charged at the same time, otherwise the voltage will drop over time.

    hope that helps
    This would be a good solution for pulling power from cig plug and wanting to give it a surge buffer. Make the buffer big enough and it could survive cold crank if you gave it a few moments to charge before starting up. On the other hand it drains battery just when you don't really want to be pulling significant accessory amps.

    It's a solution, but I'm thinking something more complete now.

  4. #4

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    When I built my carpc I just used a M3 ATX powersupply like this M3-ATX, intelligent ATX automotive power supply, 12/24V - power your PC in a car and found it worked brilliantly. The computer had no issues with being on while I turned the engine on. There are a bunch of other ones that would be better for your specific system. I didn't bother with using a netbook, as I figured I could make a faster mini ITX based system for cheaper.

    As for noise you are going to have a lot of fun with that. I assume you have done the normal shortest and best earthing possible, run power wires as far from signal wires as possible etc? Does the pitch of the noise increase as the rpm goes up? I suffered that for ages, in the end it was because I ran signal wire within 1m or so of the alternator. It was normal conversation level whine, horrific.

    I toyed around with a few filtering style things and they were all totally useless, not to say they are in all circumstances but this looks like a lot of money invested in something which may give you no noticeable improvement.

  5. #5
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    Longer term a mini-ITX PC is the end intention. For the time being the netbook is good enough and if I can find a neat docking solution that I am happy with as a permanent solution, I'll stick with it.

    It's not so much the PC that is a power issue; the netbook has it's own battery after all, but rather communications interfaces stalling and the screen powering off and needing a manual power-on in various "I just added a load" scenarios such as winding a window up and now, or plugging the netbook power in when it's batteries are down and it's pulling its maximum amps...these are things it does outside of starting too. The windows can turn the screen off engine running at idle.

    Have everything plugged in, crank the engine and start works fine. Don't fiddle with the windows though. Don't stall or almost stall it. Screen turns off when ignition is turned off but accessories still on.

    I'm thinking beyond just a PC install.

    An uninterruptible rail will give me a clean non-stop power source for any and all auxiliary periherals. screen, computer, portable printer, power invertor, or fridge and I can operate it all with the keys out of the ignition and not drain the main battery for as long as the second battery can provide power.

    I'll not be doing fridges often, but having an auxiliary power source that keeps it powered for a couple of hours with the vehicle off has got to be handy.

    The UPS 12V auxiliary power/charging rail will be good for roadtrips with small fold-out camper trailer - can be used to charge a battery bank on the trailer while travelling. And do it properly looking after the batteries with proper charge cycles.

    The auxiliary batteries will allow emergency jumping of the main supply...that's an advantage.

    It's very flexible and broad application and that's why I'm considering it because I will want more from it than just stable computer interfaces and screen. I could manage with less, but will get more out of doing the full auxiliary battery.

    Quote Originally Posted by Nepharius View Post
    When I built my carpc I just used a M3 ATX powersupply like this M3-ATX, intelligent ATX automotive power supply, 12/24V - power your PC in a car and found it worked brilliantly. The computer had no issues with being on while I turned the engine on. There are a bunch of other ones that would be better for your specific system. I didn't bother with using a netbook, as I figured I could make a faster mini ITX based system for cheaper.

    As for noise you are going to have a lot of fun with that. I assume you have done the normal shortest and best earthing possible, run power wires as far from signal wires as possible etc? Does the pitch of the noise increase as the rpm goes up? I suffered that for ages, in the end it was because I ran signal wire within 1m or so of the alternator. It was normal conversation level whine, horrific.

    I toyed around with a few filtering style things and they were all totally useless, not to say they are in all circumstances but this looks like a lot of money invested in something which may give you no noticeable improvement.


    ---------- Post added 30-11-2009 at 12:48 AM ---------- Previous post was 29-11-2009 at 10:13 PM ----------

    Quote Originally Posted by Nepharius View Post
    ... I toyed around with a few filtering style things and they were all totally useless, not to say they are in all circumstances but this looks like a lot of money invested in something which may give you no noticeable improvement.
    Not so much money - a few hundred dollars, and that will be a solution that will serve brilliantly for the PC and extra electronics, and give a reserve power source and emergency jump battery as well at the throw of a switch.

    Granted, not a huge amount of power considering I want small batteries to fit the space with the spare tyre and also weight considerations. The only sane place for a 30Kg battery is on a trailer.

    Regarding noise - that is another matter again from power as such. I would expect an isolated 12V supply should show far less noise that one with an alternator generating charge. I think there's a real possibility that the solution will kill two birds with one stone.

  6. #6
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    Looking at the specs of the M3 ATX supply - the problem is apparent when you look at the load - 120W.

    120W is the auxiliary rail maximum. So there's no headroom on the auxiliary rail when you hook up computer, screen and then other devices as well, and the overloaded supply becomes noisier...

    You may not be blowing fuses but it's pushing it to power all these things from aux. Yes you can tap the battery directly and as long as your M3 works properly it won't drain it. Screen? it will happily trickle drain the battery when off.

    Since I may well end up with a fairly elaborate electronics install, I think the second battery and supply is the way to go. Avoids overloading anything on the stock loom or battery capacity, and is a permanent solution for any and all future 12V power requirements I might have in the vehicle. As a bonus it should minimize or eliminate power rail noise.

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    Winding window effects _should_ be resolved by a voltage stabilizer alone.

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