Why so difficult to find 50V supply!!

Discussion in 'General Electronics Chat' started by MarkUK, Apr 3, 2015.

  1. MarkUK

    Thread Starter New Member

    Mar 19, 2015
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    Hi

    I work with old electro mechanical Amusement slot machines from the 60s and 70s, and it's a pain that they use pay out solenoids rated at 50 Volts - Why they ever made them like this is beyond me!!!! The whole country had 240V, USA had 110V so why on earth make these little beasts 50V???

    As you can tell, I'm having a bad day trying to buy replacement solenoids. If anyone can point me in the right direction I'd be grateful. I think I have a couple of options... try and find a push bar solenoid rated at 240v (I wish), or find a PSU that has an input of 240V but outputs 50V. (as some of these machines are not worth too much, I don't want an expensive option... any suggestions?

    Oh one more thing (sounding like Columbo now!) if I have a solenoid without any info on it, how do I know how much voltage it is.. and if its AC or DC?
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    Not sure about 50V, but you sure will be able to find a PSU that makes 48V, which is basically the same as 50.
     
  3. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    can you not replace them for 24v solenoids, there are 50v solenoids on Ebay, and 50v dc laptop psu as well, are you in UK..
     
  4. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Most 48 volt DC SMPS units can be adjusted to put out more than 50 volts so I am not seeing where this voltage requirement is a problem.
     
  5. MarkUK

    Thread Starter New Member

    Mar 19, 2015
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    thanks. I did look on ebay, Im in UK. Could not see any 50V PSU for laptops otherwise i'd buy those. I'll do some more searching I think.
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    As a side note: the reason they fail so often is if they are AC solenoids. Around that time Europe was going over to mainly DC versions, which have a lower failure rate, not to mention more efficient.
    When you say power supply, I assume you mean 50vac?
    The resistance will be a good indication if it is AC or DC, with AC being much lower.
    If looking for alternatives, you would be ahead looking for 24vdc/48vdc solenoid versions.
    Max.
     
  7. MarkUK

    Thread Starter New Member

    Mar 19, 2015
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    I had a look at RS and they have this supply
    RS 50VA 2 Output Chassis Mounting Transformer, 24 V ac
    not sure if its what I could use. Sorry I'm new to electrics and stuff and find it confusing . I know this is a silly question, but I'll ask anyway. When I see things on ebay advertised as 50VA I take it thats not the Voltage?

     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Va is the 'wattage' rating of the transformer, the max current it will supply at the rated voltage, I x V=Va.
    Did you confirm if they are AC solenoids?
     
  9. alfacliff

    Well-Known Member

    Dec 13, 2013
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    on the pinballs I used to work on, all but the strongest solenoids were 24 vdc. the flippers and such used 70 vdc, with a switch to reduce current when pulled in. there are some game part supliers around, but I havnt seen many 50 volt coils for sale. ac solenoids have a thin copper ring to keep down buzzing, not to be confused with the stacks of thick copper rings used on the older electromechanical pinball machines as release delays.
     
  10. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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  11. MaxHeadRoom

    Expert

    Jul 18, 2013
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    They all appear to be DC?
    Max.
     
  12. alfacliff

    Well-Known Member

    Dec 13, 2013
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    all our cisco internet phones use a 48 volt dc switching supply.
     
  13. Dodgydave

    Distinguished Member

    Jun 22, 2012
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  14. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The OP has not confirmed so far if the solenoids are AC or DC??:(
    No point suggesting supplies until this is known!
    Put a bridge and caps on a 50v supply and you end up with 70vdc.
    Max.
     
  15. ian field

    Distinguished Member

    Oct 27, 2012
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    The 48V PSUs are faily common as they're used in telecoms equipment.

    An open frame switcher most likely has an adjustment pot on the PCB somewhere, but its pretty unlikely the solenoids on the PO's slot machines are that fussy.
     
  16. MaxHeadRoom

    Expert

    Jul 18, 2013
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    How come everyone is assuming DC solenoids, am I missing something?:confused:
    Max.
     
  17. MarkUK

    Thread Starter New Member

    Mar 19, 2015
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    Thanks for all these suggestions. I'm impressed with the technical knowledge you guys have! Here's the deal... The machine had a 240v AC solenoid fitted, but it burnt out, so I had a similar sized one with no markings on it anywhere (this I bought a few years ago from ebay). So I don't know if its AC or DC, or how many volts. However, I did fit it, and it appears to work (but fires SO FIERCE like its getting too much power, but what do I know!!!!). So I'm guessing 240volts is too much for it which is why it fires so rapid. Question is, if this was DC would it have burned out immediatelt, or just not work at all? Also how do I know the voltage? If, because I dont know, If it is 50V, would it have blown immediately when I powered 240v through it?
    By the way, it only receives a short burst of power from a micro switch to fire it and push a coin out.
     
  18. MaxHeadRoom

    Expert

    Jul 18, 2013
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    So apparently they are AC solenoids.
    You obviously miss sized the replacement I would imagine.
    Your best bet IMO is to do a little re-engineering, if you can find a suitable DC solenoid, which unless it is really odd ball, should be relatively easy, and then come up with a simple power supply for them.
    If using a simple 24vac or 48vac transformer you can just wire a bridge directly across the output, you do not need a capacitor.
    The alternative is to use an off the shelf DC supply, which could be a little more expensive.
    You need to calculate your total current required, this depends on your solenoids selected and the number on at one time.
    Max.
     
  19. ian field

    Distinguished Member

    Oct 27, 2012
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    Feeding AC into DC solenoids would let the magic smoke out - Feeding DC to AC solenoids carries a slight risk of core magnetisation and maybe failure to release, that isn't unsurmountable.

    Most people probably assumed that since transformers with 50V secondaries aren't all that hard to come by, the OP probably wanted a DC power supply.
     
  20. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Sorry that is wrong way around, feeding AC solenoid with DC will result in a burn out (using the same rated voltage).
    The (DC) resistance of AC solenoids are very low compared to their DC counterparts of the same voltage rating.
    There was no mention of DC required anywhere in the posts?
    Max.
     
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