Free 186 More Best Homemade Tools eBook:  
Get 2,000+ tool plans, full site access, and more.

User Tag List

Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 29

Thread: SCR Motor Speed Control made from salvaged parts

  1. #1
    Supporting Member Paul Jones's Avatar
    Join Date
    May 2014
    Location
    Del Mar, California
    Posts
    1,231
    Thanks
    5,810
    Thanked 1,440 Times in 655 Posts

    Paul Jones's Tools

    SCR Motor Speed Control made from salvaged parts

    I want to share some photos of a SCR motor speed control made from salvaged parts removed from surplus rack mounted electronics. In the early 1970’s my college roommate and I made several of these motor speed controls from surplus parts and aluminum used in rack mounted electronics we found in salvage yards. The one shown in the photos is still used in my home workshop (now controls my Unimat SL 1000 lathe (see http://www.homemadetools.net/forum/m...00-lathe-10111 )).

    The salvaged printed circuit boards (PCB) and aluminum rack fronts and chassis were sold by the pound with no guarantee that anything would work. De-soldering the parts was easy using low heat soldering irons and braided copper wicks (we didn’t have the spring loaded vacuum pumps). The surplus electronics came from salvage yards in Seattle and the equipment was usually left in piles out in the rain or open-walled sheds. We always had a list of part numbers so finding best preserved parts took a lot of searching. There were always several junk yard dogs but kept caged by day and free to roam after closing. I found the salvage yards fascinating.

    We saw an article in either “Radio Electronics” or “Popular Electronics” about making a 120VAC motor speed control using a 2N3669 SCR (Silicon Controlled Rectifier) rated for 16A at 200V. In the early 70’s SCR motor speed controllers were state-of-the-art so we had to have one. The most difficult salvaged component to find was the power resistor shown mounted on the right-hand side of the chassis in photo 3 (and better yet, this power resistor was adjustable). The aluminum box was cut from aluminum rack panels and chassis enclosures (hence some of the “extra” holes) and the stainless steel machine screws came from surplus rack components. We designed and etched our own printed circuit boards, and added an extra coat of solder to the copper foils. We thought it would be cool to have the PCB plug into an edge connector to make it easier to repair blown components (never needed). Even the blank PCB material was surplus.
    Attached Thumbnails Attached Thumbnails SCR Motor Speed Control made from salvaged parts-motor-speed-control-120vac-10a.jpg   SCR Motor Speed Control made from salvaged parts-motor-speed-control-120vac-10a-side-view.jpg   SCR Motor Speed Control made from salvaged parts-motor-speed-control-120vac-10a-inside-view.jpg   SCR Motor Speed Control made from salvaged parts-motor-speed-control-120vac-10a-pcb-top-view.jpg   SCR Motor Speed Control made from salvaged parts-motor-speed-control-120vac-10a-pcb-bottom-view.jpg  


    186 More Best Homemade Tools eBook
    Last edited by Paul Jones; May 6, 2018 at 03:36 AM. Reason: Added link to Unimat SL 1000 lathe project

  2. The Following 10 Users Say Thank You to Paul Jones For This Useful Post:

    Hotz (Jun 25, 2015), Jon (Jun 25, 2015), kbalch (Jun 25, 2015), kess (Apr 19, 2018), NortonDommi (Nov 25, 2017), old_toolmaker (Apr 26, 2022), PJs (Jun 28, 2015), proff11 (Jun 26, 2015), tooly (May 1, 2022), Vyacheslav.Nevolya (Mar 2, 2016)

  3. #2
    Supporting Member Hotz's Avatar
    Join Date
    Feb 2013
    Location
    South of Brazil.
    Posts
    360
    Thanks
    157
    Thanked 75 Times in 51 Posts

    Hotz's Tools
    Speak seriously!!!

    Because these guys with the name of Paul, are good ...

    Very nice work ...

    Paul Hotz ...


    2000 Tool Plans
    Sorry my mistakes in english.
    to share your tip >>> http://www.homemadetools.net/forum/tool-tips-tricks/ <<<

  4. The Following 2 Users Say Thank You to Hotz For This Useful Post:

    Paul Jones (Jun 25, 2015), Z2V (Apr 26, 2022)

  5. #3
    kbalch's Avatar
    Join Date
    Jun 2012
    Location
    Clermont, FL
    Posts
    5,034
    Thanks
    2,275
    Thanked 531 Times in 383 Posts
    Thanks Paul! I've added your SCR Motor Speed Control to our Electronics category, as well as to your builder page: Paul Jones' Homemade Tools. Your receipt:


  6. The Following User Says Thank You to kbalch For This Useful Post:

    Paul Jones (Jun 25, 2015)

  7. #4
    kbalch's Avatar
    Join Date
    Jun 2012
    Location
    Clermont, FL
    Posts
    5,034
    Thanks
    2,275
    Thanked 531 Times in 383 Posts
    This thread has been moved to the Must Read subforum. Congrats (and thanks) to Paul for making such a valuable contribution!

  8. The Following User Says Thank You to kbalch For This Useful Post:

    Paul Jones (Jun 26, 2015)

  9. #5
    Supporting Member Catfish's Avatar
    Join Date
    Oct 2013
    Location
    Mariposa, California
    Posts
    268
    Thanks
    55
    Thanked 414 Times in 156 Posts

    Catfish's Tools
    Nice build Paul. Randy

  10. The Following User Says Thank You to Catfish For This Useful Post:

    Paul Jones (Jun 26, 2015)

  11. #6
    Supporting Member rossbotics's Avatar
    Join Date
    Dec 2013
    Location
    Florida
    Posts
    730
    Thanks
    1,019
    Thanked 1,639 Times in 402 Posts

    rossbotics's Tools
    That's cool Paul, I have a need for something like that on a machine tool I'm building, Maybe I'll make one instead of buying one,
    Awesome build guy
    Comments are always welcome
    Doug

    Subscribe to my you tube channel

    https://www.youtube.com/channel/UCDD..._as=subscriber



    Tool Plans for Sale by rossbotics






  12. #7
    Supporting Member Paul Jones's Avatar
    Join Date
    May 2014
    Location
    Del Mar, California
    Posts
    1,231
    Thanks
    5,810
    Thanked 1,440 Times in 655 Posts

    Paul Jones's Tools
    Thanks Doug. I am amazed how long the electronics have lasted considering everything was from used parts. I should add a fine mess screen to the side air vents to prevent any shorts from chips. Paul

  13. #8
    PJs
    PJs is offline
    Supporting Member PJs's Avatar
    Join Date
    Sep 2014
    Location
    Northern CA
    Posts
    1,841
    Thanks
    8,333
    Thanked 1,118 Times in 718 Posts

    PJs's Tools
    Thanks Paul, great post. Enjoyed the "surpies" connection and that it still works. Something about the old school components that are built to last and you could push them pretty hard and would recover. The diodes and transistors look familiar but couldn't read the numbers...and etching boards was the Bom back then. The Surpies & penny a pound auctions at the Naval yards were the cheap and cheerful way back then, and probably where I got my attitude about it...doing so much with so little. I've used rack panels since then, even as an engineer, and love the versatility of them. Great build from 40+ years ago...Thanks for sharing your treasure! ~PJ

  14. The Following User Says Thank You to PJs For This Useful Post:

    Paul Jones (Jun 28, 2015)

  15. #9
    Supporting Member Paul Jones's Avatar
    Join Date
    May 2014
    Location
    Del Mar, California
    Posts
    1,231
    Thanks
    5,810
    Thanked 1,440 Times in 655 Posts

    Paul Jones's Tools
    PJ,
    I thought I could help you with the part numbers and pulled the board from its edge connector. Some of the transistor cans are too corroded to read all the printed markings. The big SCR is a 2N3669, the four diodes are 1N2860A, the three transistors are 2N3754 (middle right), 2N26?9 (lower left),and unknown in upper middle position.
    Paul
    Last edited by Paul Jones; Jun 28, 2015 at 09:54 PM.

  16. The Following User Says Thank You to Paul Jones For This Useful Post:

    PJs (Jun 30, 2015)

  17. #10
    Supporting Member Christophe Mineau's Avatar
    Join Date
    Jul 2014
    Location
    France, Brittany !
    Posts
    913
    Thanks
    825
    Thanked 1,687 Times in 481 Posts

    Christophe Mineau's Tools
    Hi Paul,
    This components were made for lasting, planned obsolescence was not yet a business strategy ...
    Just for my understanding, what is the principle ?
    Is it like chopping the mains sinusoid, triggering a thyristor at an adjustable phase ?
    Cheers !
    Christophe
    ________________________________________________________________
    Visit my Website : http://www.labellenote.fr/
    Facebook : La Belle Note
    All my personal works, unless explicitly specified, are released under
    Creative Commons BY-NC-SA license.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •