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Thread: Heathkit Darkroom timer revealed glory!

  1. #21
    ic-racer's Avatar
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    Re: Heathkit Darkroom timer revealed glory!

    Randy, you always have cool stuff to post. This is the schematic. The tube (0A2) is a voltage regulator to ensure consistent times. There is a single silicone component (SCR, the black device that looks like a transistor). I repaired an OMEGA timer that was all analog, like this unit, and the only bad component was the SCR.

  2. #22
    ic-racer's Avatar
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    Re: Heathkit Darkroom timer revealed glory!

    When I was younger, I could not afford the fancy Heathkit timer, so I made mine from RadioShack parts using an article in Popular Electronics. Mine used the digital 555 timer chip that had just come out and a 'modern' TO-220 type voltage regulator.

  3. #23
    Tin Can's Avatar
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    Re: Heathkit Darkroom timer revealed glory!

    Quote Originally Posted by ic-racer View Post
    Randy, you always have cool stuff to post. This is the schematic. The tube (0A2) is a voltage regulator to ensure consistent times. There is a single silicone component (SCR, the black device that looks like a transistor). I repaired an OMEGA timer that was all analog, like this unit, and the only bad component was the SCR.
    Thanks!

    And double thanks for the schematic!
    Tin Can

  4. #24

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    Re: Heathkit Darkroom timer revealed glory!

    That Heathkit is a really clean build--beautiful work. You lucked out with the quality. I recently built a headphone amplifier kit and really enjoyed the process. I'll be starting a second "kit" soon--more like a bag o' parts, so I'll have to do some homework to test the circuit voltages.




  5. #25
    Tin Can's Avatar
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    Re: Heathkit Darkroom timer revealed glory!

    Yes the audio guys still want TUBES!

    Great project Barry.
    Tin Can

  6. #26

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    Re: Heathkit Darkroom timer revealed glory!

    Thanks Randy. Yes, tubes are very big in the enthusiast audio world. You wouldn't believe the prices of some of the NOS tubes--they're insane.

    Quote Originally Posted by Randy Moe View Post
    Yes the audio guys still want TUBES!

    Great project Barry.

  7. #27

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    Re: Heathkit Darkroom timer revealed glory!

    Quote Originally Posted by BarryS View Post
    ... I recently built a headphone amplifier kit and really enjoyed the process...
    ___

    Barry... You did a very nice job with your Bottlehead Crack OTL Headhone Amplifier Kit.
    Congratulations!

    Are you perhaps thinking... Of doing the 'Speedball' Upgrade? (*You really should)...
    --
    Best regards,

    Tim.
    _________

  8. #28
    Corran's Avatar
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    Re: Heathkit Darkroom timer revealed glory!

    Quote Originally Posted by ic-racer View Post
    so I made mine from RadioShack parts
    Nice. Too bad RS is mostly cell phones and cheap junk these days. And in bankruptcy too. No surprise.
    Bryan | Blog | YouTube | Instagram | Portfolio
    All comments and thoughtful critique welcome

  9. #29
    2 Bit Hack
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    Re: Heathkit Darkroom timer revealed glory!

    Quote Originally Posted by BarryS View Post
    Thanks Randy. Yes, tubes are very big in the enthusiast audio world. You wouldn't believe the prices of some of the NOS tubes--they're insane.
    You should see the prices for tube type guitar amps.
    Regards

    Marty

  10. #30
    Tin Can's Avatar
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    Re: Heathkit Darkroom timer revealed glory!

    I have a high end audio store near me. I checked out their low end $2000 tube system, all hooked up and playing my type of music, not rock and roll. Very nice, but I won't spend that much on audio.

    My hearing is not that good, sure I can discern differences, but I am more visually aligned than auditory. Tinnitus requires masking sounds.

    My 20 year old Aiwa system is good enough for my space, it never is off.
    Tin Can

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