High Voltage DC Regulator

Discussion in 'Analog & Mixed-Signal Design' started by andrewjpas, Dec 7, 2017.

  1. andrewjpas

    Thread Starter New Member

    Dec 7, 2017
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    Good Morning

    I have been searching for a while now trying to locate a regulator that will accept a variable DC voltage from 10-120v and supply a constant output of 3v 50ma, having been unable to find anything to meet these requirements i thought i would ask here if anything like that is available or maybe someone can suggest another option

    It is basically to an give conformation via an LED than various DC motors we have built into a piece of equipment have a supply voltage as the kit in question is not easily accessible.

    kind regards

    Andrew
     
  2. dendad

    Distinguished Member

    Feb 20, 2016
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    Does the motor supplies vary that much, or are they PWM?
    What size are the motors? And do you actually just need an LED?
    What about something like this? You get a motor voltage reading.
    https://www.ebay.com.au/itm/Voltmet...855279?hash=item1ec8618d6f:g:nfMAAOSwCQZZLoc~
    You will need to add a supply, a 5V or 12V plug pack will do.

    It would help to supply a circuit of how the motors are wired and what drives them.
     
  3. andrewjpas

    Thread Starter New Member

    Dec 7, 2017
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    Hi, Thanks for the reply,

    There are 6 motors in total all controlled by DC Drives and each one by its own potentiometer, the voltages do vary completely through that range unfortunately, quite tempted to go with the idea you have suggested as we will get an indication of voltage as well.

    The idea was just to keep the unit very small as we wanted to mount it in the back of a connector housing, i have attached a small schematic but doubt it will be any use other than what i have explained

    many thanks

    Schematic.jpg
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    You might find a standard USB charger/adapter would work with that supply range. They're cheaply available, so worth a try. A single resistor per LED could then provide current limiting from the 5V output.
    Alternatively, use a USB charger/adapter from the mains as a 5V supply, then use the motor voltages to switch transistors which activate the LEDs, powered from 5V.
     
    Last edited: Dec 7, 2017
  5. dendad

    Distinguished Member

    Feb 20, 2016
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    If you just want an on/off indication, something like this could work.
    The LM399 has 4 x comparators so it could look at 4 motor signals.
    http://www.ti.com/lit/ds/symlink/lm2901.pdf
    VoltSense.jpg
    This is pretty rough but could be a start.
     
  6. andrewjpas

    Thread Starter New Member

    Dec 7, 2017
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    Excellent thanks very much for the replies, going to do a little bit of research and have a play
     
  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Here's how a USB source could power an indicator LED :-
    Indicator.PNG
     
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    ..... and to minimise components you could use a single LED to check that there is >~0.7V at all motors (providing the motors are of a type which present a low impedance when unpowered and don't mind ~1mA of current being fed into them via R1) :-
    Indicator2.PNG
     
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