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Thread: Cobra-matic : Retro Bakelite Phonograph

  1. #41
    Retrosmith Mach's Avatar
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    Default Re: Cobra-matic : Retro Bakelite Phonograph

    More like below. I'm shorting the contact because its a break before make switch. I didn't think that the motherboard sense wire (green wire) carried mains power. I'll put a multi-meter across it tonight.

    Pole 1
    1-1 OFF
    1-2 Green mother board sense wire
    1-3 Shorted to 1-2
    1-4 Shorted to 1-2

    Pole 2

    2-1 Empty
    2-2 Empty
    2-3 Motherboard header "On" with circuit described
    2-4 Motherboard header "Reset" with spring return so no circuit needed

    Does this make sense, more importantly do you see a problem? Thanks much for the input.

  2. #42
    SOB Fettler xmastree's Avatar
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    Default Re: Cobra-matic : Retro Bakelite Phonograph

    Quote Originally Posted by Mach View Post
    In a modding frenzy, the idea evolved that I could use the first position on the knob to replace the switch on the back of the power supply (which would have been hidden in the case). That means 115 volts through the center of the case attached to an antique radio switch.
    Quote Originally Posted by Mach View Post
    I didn't think that the motherboard sense wire (green wire) carried mains power.
    Now I'm confused as to what you are trying to achieve with this switch. The earlier post suggested you want to interrupt the mains, replacing the black switch on the back of the PSU.

    And why are you messing with the green wire at all?

    By far the simplest solution is to leave the mains alone, and just use the momentary switch to operate either the power or the reset. If you must turn off the mains too, it's still possible, but the switch needs to stay in two positions.

    I think the wiring would be:
    Pole 1 mains in
    1/1 NC
    1/2 mains out
    1/3 mains out (2-3 connected together so there's power in both positions)

    Pole 2 one side of pulse trigger
    2/1 NC
    2/2 other side of trigger
    2/3 other side of trigger (again, 2-3 connected)

    Pole 2 one side of mobo reset header
    2/1 NC
    2/2 NC
    2/3 other side of mobo reset header

    So, position 1, mains is off, nothing else matters.
    Position 2, mains on, power signal is pulsed
    Position 3, mains still on, power unaffected, reset is activated.

    It would be nice if the spring could make pos'n 3 spring back to pos'n 3

    Also, the switch needs to me make before break or you'll interrupt the power when going for the reset, and probably retrigger the power on pulser too.

    Personally, I wouldn't mix mains and low voltage on the same switch. I'd just go with the simple solution. Failing that, get a wafer switch and two wafers, one regular and one for the mains.

    Quote Originally Posted by aintnothang View Post
    Think of a way to simulate a real bullet hole, like shooting it.

  3. #43
    Religiously tolerant. Luke122's Avatar
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    Default Re: Cobra-matic : Retro Bakelite Phonograph

    I think the original plan was to jumper the green wire, then use the mains switch to power up the psu.

    He then realized that it wasnt a very safe idea, so removed the line to the mains switch, and instead wants now to use the green line on the 20pin connector to power up the board.

    Doing so *would* technically save you from having to add a power switch to the header pins on the mobo, so if you are really against having unnecessary cabling to the board, this option *should* work.

    HOWEVER.. xmastree's idea is better.

    \m/ d(-_-)b \m/

    R9 290X+Kraken+Corsair H90, Xeon 5649@4ghz, Asus P6T-WS Pro

  4. #44
    Retrosmith Mach's Avatar
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    Default Re: Cobra-matic : Retro Bakelite Phonograph

    Hmm, Luke122 has the general gist of it. Original plan was to move the mains power (but that didn't seem very safe). So xmastree the plan was to replace the toggle switch on the psu.

    Then I thought that I could in essence do the same thing by switching at the atx connector green wire instead of the toggle switch replacement. I thought this because the power supply doesn't work without the jumper on the green wire. I assumed that the power supply is dead if the green wire is not connected. I'm starting to believe that's wrong given the confusion. In other words, the psu is hot when plugged to mains with the toggle switch on and the atx connector not jumpered. Yes?

    As you mentioned, mains connection on same switch with low voltage is bad so I'll do as you suggest but with just the motherboard header. I can change the rotary swich to a make before break and a 3 position fairly easily with the spring back to position 3.

    So

    1/1 NC
    1/2 pulse circuit->MB header On
    1/3 MB header Reset with spring return to On with a solder bridge across the contact path from 2-3

    Any clearer? Thanks for the patience.

  5. #45
    SOB Fettler xmastree's Avatar
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    Default Re: Cobra-matic : Retro Bakelite Phonograph

    Quote Originally Posted by Mach View Post
    I assumed that the power supply is dead if the green wire is not connected.
    No, it's still live. Basically the motherboard makes or breaks that connection as necessary. There's really no need to touch it.

    1/1 NC
    1/2 pulse circuit->MB header On
    1/3 MB header Reset with spring return to On with a solder bridge across the contact path from 2-3
    You don't need the pulser either.

    Spring load the switch to pos'n 2. Then 1 - on, 3 = reset.

    That way you can also hold it in pos'n 1 to force a power down if necessary.

    Quote Originally Posted by aintnothang View Post
    Think of a way to simulate a real bullet hole, like shooting it.

  6. #46
    Retrosmith Mach's Avatar
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    Default Re: Cobra-matic : Retro Bakelite Phonograph

    Ok I think I understand. I'll give it a go this weekend. Thanks!!

  7. #47
    A big old Tease Apparently DonT-FeaR's Avatar
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    Default Re: Cobra-matic : Retro Bakelite Phonograph

    glad you do because i dont =) nice paint work
    Quote Originally Posted by Drum Thumper View Post
    you tease!

  8. #48
    SOB Fettler xmastree's Avatar
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    Default Re: Cobra-matic : Retro Bakelite Phonograph

    Quote Originally Posted by Mach View Post
    Ok I think I understand. I'll give it a go this weekend. Thanks!!
    Quote Originally Posted by DonT-FeaR View Post
    glad you do because i dont =) nice paint work
    Right, it seems that what's obvious to me may not be quite so obvious to non-electronic engineers, so here's a quick and dirty diagram.

    Most rotary switches are supplied in multiples of 12. So that's 1x12, 2x6, 3x4, 4x3, 6x1. Mach is using a 4 pole 3 way, so I've drawn that one.



    You'll see that it's normally in position 2. The four poles are labelled A-D to save confusion.

    The animation is pretty close to the actual construction of the switch.

    Power on is position 1, so connecting two wires, one to A and one to the 1 associated with A will short them together when the switch is turned to position 1. Releasing it back to the centre opens them again.

    The reset works similarly, but using position 3 so using a different pole, two wires again, same principle.

    Is it clear now?

    Quote Originally Posted by aintnothang View Post
    Think of a way to simulate a real bullet hole, like shooting it.

  9. #49
    A big old Tease Apparently DonT-FeaR's Avatar
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    Default Re: Cobra-matic : Retro Bakelite Phonograph

    you could of just said that i get it now sounds really cool
    Quote Originally Posted by Drum Thumper View Post
    you tease!

  10. #50
    Retrosmith Mach's Avatar
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    Default Re: Cobra-matic : Retro Bakelite Phonograph

    Thanks for the great diagram xmastree! That makes it much clearer. It's taken me a while to get my head around the interaction of the psu, MB, and switch. I'm having a good time with it though. The soldering iron is my new favorite tool.

    @DonT-Fear: Thanks! I was able to sneak some clear coat on this weekend. A run on the bezel that will need to be sanded out but it turned out much better than expected. I'm traveling this week in the UK so pics after I get back.

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