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O/T How can I control voltage output?

Discussion in 'Off Topic Threads' started by Shooting Jack, Jul 31, 2011.

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  1. Shooting Jack

    Shooting Jack Active Member

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    I have a motor that is also a generator but it puts out 17 volts and my stereo will not stay on due to the high voltage. I've gone to radio shack to try to find something to fix this problem but no one there has a clue. Any simple fix out there that you know of? The stereo works fine just off the battery or when the motor is idling but as soons as the generator revs up the stereo starts cutting out. Jackie B.
     
  2. wireguy

    wireguy TS Member

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    Not enough info about the unit. If it is intended to deliver 12 nominal volts it should have some kind of regulator in the output circuit.
     
  3. chipking

    chipking TS Member

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    Zener Diode regulator


    The Zener Diode Regulator

    Zener Diodes can be used to produce a stabilised voltage output with low ripple under varying load current conditions. By passing a small current through the diode from a voltage source, via a suitable current limiting resistor (RS), the zener diode will conduct sufficient current to maintain a voltage drop of Vout. We remember from the previous tutorials that the DC output voltage from the half or full-wave rectifiers contains ripple superimposed onto the DC voltage and that as the load value changes so to does the average output voltage. By connecting a simple zener stabiliser circuit as shown below across the output of the rectifier, a more stable output voltage can be produced.

    Zener Diode Regulator


    [​IMG]


    Use a 12V Zener Diode. Tell the folks at radio shack this is what you want (show them the picture if needed but good luck with clerks) or talk to a old time radio or ham guy or repair shop for help. This will give you a very stable output.

    OR Talk to your local antique car guy and get a external voltage regulator like all the 50's and 60's autos used.

    --- Chip King ---
     
  4. halfmile

    halfmile Well-Known Member

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    And put it on a heat sink.

    The 70's era Norton, Triumph and BSA Motorcycles had one under the tank. It had an aluminum plate to dissipate the heat from the excess current.

    It was also blessed with a very handy stud mount and a common type 1/4 inch tab connector.

    Find one of those beauties and you are home free.

    HM
     
  5. Hal1225

    Hal1225 Member

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    How about a variable transformer hooked to your out put and set to 12V.

    Harry
     
  6. trapperpg

    trapperpg Member

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    The motorcycle regulators are probably going to be your best bet. Something such as this regulator for HD sportster.


    http://www.debrix.com/Black-Anodized-12-Volt-10AMP-Regulator-Harley-XL-S-p/16250-m1.htm

    pg
     
  7. halfmile

    halfmile Well-Known Member

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    Some of the 70's Mopars had a solid state regulator on the firewall. El Cheapo at the salvage yard.

    HM
     
  8. Leo

    Leo Well-Known Member

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    Too bad radio shack only hires kids that play video games and talk on cell phones. Radio Shack does have a nice compact integrated circuit voltage regulator in their stock. As a matter of fact, they have a 5 volt and a 12 volt and are a convienient TO-220 case style. These are made to regulate an output, which is what you want. In addition to the 12 volts nominal need, you have to be concerned about the current (amps) also. Not all voltage regulator circuits can supply the needed amperage to power a stereo. Automotive regulators work by changing the stator input on the alternator to control the voltage on the Alternators output. That would not be a good application for your need. I don't have time now, but google "IC voltage regulator" and you will find more information.
     
  9. Leo

    Leo Well-Known Member

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    rjh, that looks like it will do it. At that price, it would not be worth buying the parts and making it yourself.
     
  10. Shooting Jack

    Shooting Jack Active Member

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    Thanks everyone. I contacted battery space for a regulator as it is exactly what I needed. I appreciate all of your responses. Jackie B.
     
  11. sliverbulletexpress

    sliverbulletexpress TS Member

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    Don't know about motorcycle regulators but old and new car regulators vary the field current in one way or another to limit the output of the generator/alternator, ain't gonna work for this application if you just try to put it inline to reduce the voltage. The old generator regulators had a set of points that sat there and vibrated to adjust the field current, newer ones use electronics.

    The battery space regulator on that page is rated for 4 amps, might not be enough for a kickin stereo.

    I would be looking into ways of adjusting the voltage at the generator. There should be a regulator of some kind on the generator. Is it military by any chance? Anything downstream that converts electricity into heat is very inefficient and will fail eventually.
     
  12. slic lee

    slic lee Active Member

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    Why spend money for a variable unless its just there, same for one with a diode, a plain solid 12 V for insurance a 13 volt bus fuse in front?
     
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