Possible Supply from Old Phone System

Discussion in 'General Electronics Chat' started by CoachKalk, Oct 14, 2011.

  1. CoachKalk

    Thread Starter Member

    Sep 20, 2011
    139
    2
    I have had some sort of old phone system that came with a building we bought several years ago. Actually, my brother-in-law thought he could sell it. Anyway, 2+ years later, it still sits in a back closet.

    I opened it up to see if it may be of use to me. I am working on a dark sensor/counter set-up that I had planned just using a wall wart for.

    But, I have also ordered some jumbo 5" 7-seg LED displays that elec mech says need approx. 18V. Perhaps a wall wart is still the best option, but I snapped a few pictures of what I have and would like any input/suggestions on what you see.

    Is it a feasible option? Or run as fast as I can away from it? I also included a pic of the "board" portion as well - just to show how much "stuff" this thing has. I have no idea what it does other than it handled the phones - but it's gianormous!

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    And the board ...
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  2. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
    1,222
    I think you will be better of with some sort of cheap switchmode power supply for your application. Also from a safety aspect. Remember that the power supply must also meat the current need for your project. Not only voltage
     
  3. K7GUH

    Member

    Jan 28, 2011
    191
    23
    If you own a boat, use it for an anchor. Otherwise, strip the unit for whatever parts you can salvage and use, then toss the rest. Just one curmudgeon's opinion, you understand.
     
  4. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    yeah, if you are gonna need atleast 18v to power the LED's, this only has unregulated 15V at most, by the time you regulate it and all, you will loose a couple more volts, but as K7GUH said, strip what you can from it (if there is even anything salvageable from it, considering the age of it, the caps are probably nearly dried out, and most IC's are most likely obsolete) and use the rest for an anchor :)
     
  5. #12

    Expert

    Nov 30, 2010
    16,298
    6,809
    Save the transformer, the large transistors and their heat sinks, and maybe the power input panel with filter.
     
  6. iONic

    AAC Fanatic!

    Nov 16, 2007
    1,420
    68
    As stated above, the best option for your applications needs is a SMPS with the proper voltage/current specifications. Otherwise, the unit, whatever it is, is not in bad shape and there are some part that could come in handy, the heat-sinks for one.

    I'm not a big fan of wall-warts and especially of titanic-sized transformers. your house will implode with the wasted energy they suck up.:eek:
    On the other hand they may reduce your heating bill substantially at the cost of increasing your electric bill!

    I'd pull parts and scrap the rest, but maybe someone else knows what it is and could suggest what it could be used for aside from an electric BBQ.:confused:
     
  7. CoachKalk

    Thread Starter Member

    Sep 20, 2011
    139
    2

    It looks like this is better suited for the junk pile and my limited experience/knowledge had my next step being wall warts. I have now looked into the SMPS option (until you mentioned it, I had no idea of their existence) and I have a newbie stupid question. I looked at the Mouser website and found a Mean Well PD45B 2 channel SMPS CH1 - 5V, CH2 - 24V. I haven't looked at the specs in great detail yet, but my stupid question is this - do these components provide both voltages at the same time? Meaning I can use the smaller voltage to power my clock circuit and the larger voltage to my 5" LED's? Or do they provide 1 or the other, not both to separate circuits?
     
  8. tgotwalt1158

    Member

    Feb 28, 2011
    111
    18
    The +/- 5V on your power supply section of equipment shows, it is using older digital circuitry, while +/- 15V availability is the indication of using op-amp. The last pic is quite mouth watering, since you could desolder lot of components from there and may use. The size of transformer gives the idea that its a series power supply not an SMPS. Even then you could use it in your project by placing suitable voltage regulator IC's in its out put as per your required out put voltages viz. +/- 5V, +/- 9V, +/- 12V etc., provided the current output of this supply is at least equal or greater than your required consumption at suitable output voltages.
     
    Last edited: Oct 15, 2011
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