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How to Build a Voltage Regulator for $3

Discussion in 'The Hokey Ass Message Board' started by 49 Custom, Feb 19, 2010.

  1. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,406

    Flat Ernie
    Tech Editor

    Done
     
  2. I also used the same LM7806 without the capacitors and it works just fine for the fuel gage on my 37 Chevy.
     
  3. daveismissing
    Joined: Nov 9, 2008
    Posts: 6

    daveismissing
    Member
    from north eh

    I'd be worried about tantalums surviving a load dump transient.
    The other caps mentioned would be preferrable IMHO.
    Dave
     
  4. Filter caps are not necessary in most pure DC applications. Additionally, the LM7806 has internal filters that provide 70+ dB of ripple rejection...every 6 dB of rejection cuts the voltage in half, so the internal filters will halve the tiny ripple voltage 12 times, rendering it irrellevant. It is true that the capacitors don't cost much, but they do provide another possible point of failure, and the classic capacitor failure mode is dialectic breakdown, which is essentially a short. In this circuit, that means a short to ground. I wouldn't use them in this application, but I am sure there are other engineers who would because redundancy seems to be a popular theme in the field.
     
  5. great thread! these vr's are really great and are small. last one i did i used old heat sink off computer fan.
     
  6. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 5,404

    Ebbsspeed
    ALLIANCE MEMBER

    Last edited: Feb 24, 2010
  7. farmalldan
    Joined: Sep 4, 2009
    Posts: 140

    farmalldan
    Member
    from Duncan, OK

    I just ordered 10 to see what I got. I had the same thoughts you expressed. I'll let everyone know how it turns out.
     
    41rodderz likes this.
  8. markjenks
    Joined: Aug 31, 2009
    Posts: 384

    markjenks
    Member

    For $4 with free shipping, considering they are probably made over there anyways, I'm not too worried about it.

    If I lose my $4, I'm not really going to worry about it. I'll just have to skip drinking a few beers on Friday night.
     
  9. gearhead1952
    Joined: Dec 17, 2006
    Posts: 306

    gearhead1952
    Member
    from Arvada, CO

    Ford used a resistor wire instead of an actual ballast resistor for coil circuits, sorry I don't have a part number. But I took one cut it in half and used it as the dropping resistor for a 6v ahooga horn on a 12v car. Maybe try a ballast resistor for the wipers.
    Great tech article.
     
  10. 1950ChevySuburban
    Joined: Dec 20, 2006
    Posts: 6,188

    1950ChevySuburban
    Member Emeritus
    from Tucson AZ


    I've been using Mopar starter relays for years for these horns with no failures! (And lots of usage):eek:


    Great post on the regs, I love stuff like this!
     
  11. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,406

    Flat Ernie
    Tech Editor

    A starter relay would definitely handle the current from a 6V horn on 12V. My comment was meant for the 12V horn relays used to replace the 6V horn relays in most applications - work fine with 12V horns, but not so well with 6V horns on 12V and double the current.:D
     
  12. jbrittonjr
    Joined: Sep 10, 2009
    Posts: 105

    jbrittonjr
    Member

    Great article!
    Thanks!
     
  13. BigChief
    Joined: Jan 14, 2003
    Posts: 2,084

    BigChief
    Member

    Excellent post!

    For those of you who don't want to or can't solder or want an OEM alternative solution here's a little pricier option. Pretty much every Ford vehicle up through at least well into the 1970s (probably into the 80's as well) used fuel/oil/water gauges that operated on 5-6 volts. They never changed them...probably not until quite recently.

    SO, what that means is that every single Ford from the 1930's up to who knows when had 6V gauges and when 12V negative ground systems came into play they also had a voltage regulator on the the gauge panel and/or in-line to help keep the gauges alive and happy at 5-6 volts ....this is also sometimes refered to as a 'voltage stabilizer' if your talking to some parts guys. The cars, truck, vans, etc from around 1960 through 1969 had an easy to adapt regulator that looked like the one here. All you need is a place to screw it down and just plug it in. The Motorcraft part number is/was SW6325. IF the kid running the computer needs an application because he doesn't know what a book/cataloge is then just ask for one for a '68 F100 or a '68 Mustang. I think NAPA still carries them, some of the better/older parts stores may carry them as well. The Ford restoration places all carry them. Just be sure to get one for a 1960-1968 Ford anything. Some 69's and most everything after 1970 had a similar design that 'snapped' into a flex circuit on the gauge panel....less user friendly for us hotrodders.

    Enjoy!

    -Bigchief.
     

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  14. brigrat
    Joined: Nov 9, 2007
    Posts: 5,355

    brigrat
    Member
    from Wa.St.

    It just gets better and better, thanks!
     
  15. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,406

    Flat Ernie
    Tech Editor

    BigChief - aren't those just chopper circuits? Not that it would matter much with early Ford gauges...
     
  16. bikeguydave
    Joined: Aug 16, 2009
    Posts: 226

    bikeguydave
    Member
    from Kentucky

    Please school me, will one still be needed for each gauge? Thanks, Dave
     
  17. thunderbirdesq
    Joined: Feb 15, 2006
    Posts: 6,940

    thunderbirdesq
    Member

    Nope, one for the whole sha-bang!
     
  18. bikeguydave
    Joined: Aug 16, 2009
    Posts: 226

    bikeguydave
    Member
    from Kentucky

    Thanks thunderbirdesq!
     
  19. Thanks for that info. I have an old 6v swoop tacho that goes to 6000rpm I want to run in my dodge, problem now solved.
    Cheers.
     
  20. bikeguydave
    Joined: Aug 16, 2009
    Posts: 226

    bikeguydave
    Member
    from Kentucky

    FWIW, Motorcraft # SW6325 crosses to Ford # 6L2Z13D730BAA, Napa and Autozone can't cross this number, dealer only item?, retail price at local dealership, $103.56, ouch!, 4 runtz type...$60.00...Dave
     
  21. Kan Kustom
    Joined: Jul 20, 2009
    Posts: 2,665

    Kan Kustom
    Member

  22. 1950ChevySuburban
    Joined: Dec 20, 2006
    Posts: 6,188

    1950ChevySuburban
    Member Emeritus
    from Tucson AZ


    NAPA still has these, around 9-12 bucks. Called an IVR. Used into the '90s on large box trucks, maybe others...

    Also, those snap fittings are the same as 9v battery ones.
     
  23. bikeguydave
    Joined: Aug 16, 2009
    Posts: 226

    bikeguydave
    Member
    from Kentucky

    Hey 50chevy, you wouldn't have a NAPA number would ya?, IVR stand for instrument voltage regulator?...Dave
     
  24. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,406

    Flat Ernie
    Tech Editor

    And $0.10 for an L7806 CVR...
     
  25. Kramer
    Joined: Mar 19, 2007
    Posts: 911

    Kramer
    Member

    Cool idea. I don't have gauges I need to reduce the voltage on, but I was wondering how much power/amps a power transistor in the circuit would handle? I have a 6V ah-oo-gah horn I want to use on my 12v system.

    Oops! Just finished reading the rest of the posts, should have before I posted. I will not run by 6v Ah-0oo-gah horn on 12v however as it is not a regular horn and I do not want to burn it up. I will look into a ceramic resistor type.
     
    Last edited: Feb 25, 2010
  26. I wanna see MORE of the bike in your avatar
     
  27. Kramer
    Joined: Mar 19, 2007
    Posts: 911

    Kramer
    Member

    Napa number is ECH IR1
     
  28. 49 Custom
    Joined: Apr 17, 2009
    Posts: 282

    49 Custom
    Member

    I definitely looked into other solutions such as the IR1; what I liked about the separate LM7806's was that it made it easier to sort problems by segragating each circuit and much more cheaply. For those who are curious, the "old" Ford component mentioned above is electomechanical and works in a similar fashion to a points system. If you manage to find one on a junked 60's-70's Ford, it should be just fine. (I also own a '66 Mustang, so I can vouch for their durability!)

    Someone else also asked about using a power transistor to increase the usable current on an LM7806; it definitely can be done and uses only one IC. Downside is that it requires a much larger heatsink and a safe place to mount it. (There were a couple of posts that mentioned that a heatsink wasn't necessary at all for the LM7806; naturally it depends upon the draw from your gauges. I suggested it to be on the safe side and meet everyone's needs.)

    Thanks for all the comments, folks!

    -Stefan
     
  29. Frank K
    Joined: Dec 9, 2005
    Posts: 186

    Frank K
    Member

    Thanks, how do you convert an ammeter to a voltmeter? Frank Kunkel
     
  30. Do you have a RS part no. for the heatsink?

    Thanks
     

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