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Can I make voltage multipliers from several ULN2003A Darlington Array IC chips? tia sal2

Discussion in 'Electronic Basics' started by [email protected], Apr 27, 2006.

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  1. Guest

    Greetings All

    Can I make voltage multipliers from several ULN2003A Darlington Array IC
    chips?

    I'm trying to increase the voltage out my National Instruments usb-6008. I
    have several ULN2003A DARLINGTON ARRAYS I was wondering if I could use
    these as VOLTAGE MULTIPLIERS. I have 3v coming out my usb6008 and I'm
    trying to get to about 16v or would I need to use a different chip.

    Anyone have any examples with this chip? I'm using Multisim 9 to test
    different configurations out.

    Tia Sal2
     
  2. no_one

    no_one Guest

    it is AC? I don't believe that you can build a diode-capacitor voltage
    multiplier with DC.
     
  3. Chris

    Chris Guest

    Hi, Tia Sal. Your idea won't work. The input to a voltage multiplier
    needs to source *and* sink current -- the ULN2003 only sinks. Not only
    that, but the darlington output means the output voltage never goes
    below 1V, no matter how little current it's sinking. Once you subtract
    another diode drop, you'll need a lot of stages to get to 16V.

    Before anything else, though, it's odd you say you've got 3V. The spec
    sheet says you get 5V at 200mA max at the output I/O connector. This
    comes direct from the USB, I think.

    Now if you were on a desert island and a ULN2003 was all you had, or if
    an evil genie or professor were holding your feet to the fire, you
    might be able to get away with switching an inductor on and off without
    using the ULN2003 internal diode, and then use a diode, cap and zener
    to give you a very low current 16V supply like this (view in fixed font
    or M$ Notepad):

    |
    | VCC
    | +
    | |
    | C|
    | C| L
    | 1/7 C|
    | ULN2003 |
    | |\ |1N4148
    | -| >O---o->|-o----o----o
    | |/ +| |
    | 47uF --- /-/1N4745A
    | 35V --- ^ Vz=16V
    | | |
    | === ===
    | GND GND
    |
    (created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

    You need a good value inductor to give you the inductive kick, and it
    should have a DC resistance of at least 20 ohms (4V / .2A). If that's
    a problem, you might want to play with the duty cycle, and have a local
    supply for the inductor separated by a 20 ohm resistor and, say, a
    220uF cap like this:

    |
    | ___
    | VCC+o-|___|-o------.
    | 33 ohm +| |
    | 220uF--- |
    | 16V --- |
    | | C|
    | GND C| L
    | 1/7 C|
    | ULN2003 |
    | |\ |1N4148
    | -| >O---o->|-o----o----o
    | |/ +| |
    | 47uF --- /-/1N4745A
    | 35V --- ^ Vz=16V
    | | |
    | === ===
    | GND GND
    |
    (created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

    This will allow you to choose a DC coil resistance that keeps current
    as less than the max for the ULN2003. Again, you'll have to leave pin
    16 open (which might mess up your other plans with the ULN2003, if
    you're switching anything else inductive).

    If this is a real-world project, this is a little cheesy -- you
    definitely should use a DC-to-DC converter instead of this unless you
    only need a couple of mA and good regulation isn't a problem.

    Don't worry about having spare stuff left over when you're done with a
    project. It's not like the broccoli your mom served you. You should
    be crafty, but you don't have to use 'em all.

    And make sure to read the data sheets, sir. They're not printed
    because the manufacturers hate trees. And you can always get the .pdf
    file if you're concerned about the clutter of paper, or have
    environmental reservations.

    Go Aztecs!
    Chris
     
  4. Chris

    Chris Guest

    Hi, Tia Sal. Your idea won't work. The input to a voltage multiplier
    needs to source *and* sink current -- the ULN2003 only sinks. Not only
    that, but the darlington output means the output voltage never goes
    below 1V, no matter how little current it's sinking. Once you subtract
    another diode drop, you'll need a lot of stages to get to 16V.

    Before anything else, though, it's odd you say you've got 3V. The spec
    sheet says you get 5V at 200mA max at the output I/O connector. This
    comes direct from the USB, I think.

    Now if you were on a desert island and a ULN2003 was all you had, or if
    an evil genie or professor were holding your feet to the fire, you
    might be able to get away with switching an inductor on and off without
    using the ULN2003 internal diode, and then use a diode, cap and zener
    to give you a very low current 16V supply like this (view in fixed font
    or M$ Notepad):

    |
    | VCC
    | +
    | |
    | C|
    | C| L
    | 1/7 C|
    | ULN2003 |
    | |\ |1N4148
    | -| >O---o->|-o----o----o
    | |/ +| |
    | 47uF --- /-/1N4745A
    | 35V --- ^ Vz=16V
    | | |
    | === ===
    | GND GND
    |
    (created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

    You need a good value inductor to give you the inductive kick, and it
    should have a DC resistance of at least 20 ohms (4V / .2A). If that's
    a problem, you might want to play with the duty cycle, and have a local
    supply for the inductor separated by a 20 ohm resistor and, say, a
    220uF cap like this:

    |
    | ___
    | VCC+o-|___|-o------.
    | 33 ohm +| |
    | 220uF--- |
    | 16V --- |
    | | C|
    | GND C| L
    | 1/7 C|
    | ULN2003 |
    | |\ |1N4148
    | -| >O---o->|-o----o----o
    | |/ +| |
    | 47uF --- /-/1N4745A
    | 35V --- ^ Vz=16V
    | | |
    | === ===
    | GND GND
    |
    (created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

    This will allow you to choose a DC coil resistance that keeps current
    as less than the max for the ULN2003. Again, you'll have to leave pin
    16 open (which might mess up your other plans with the ULN2003, if
    you're switching anything else inductive).

    If this is a real-world project, this is a little cheesy -- you
    definitely should use a DC-to-DC converter instead of this unless you
    only need a couple of mA and good regulation isn't a problem.

    Don't worry about having spare stuff left over when you're done with a
    project. It's not like the broccoli your mom served you. You should
    be crafty, but you don't have to use 'em all.

    And make sure to read the data sheets, sir. They're not printed
    because the manufacturers hate trees. And you can always get the .pdf
    file if you're concerned about the clutter of paper, or have
    environmental reservations.

    Go Aztecs!
    Chris
     
  5. Jasen Betts

    Jasen Betts Guest

    what's a voltage multiplier?
    that could work. the ULN2003 can switch voltages in that range and only
    needs a small control input. you will need an "about 16V" power supply.
    I bet there's a heap of examples in the data sheet.
     
  6. jack

    jack Guest

    You set up the transistor array as a multivibrator -- use this to drive a
    coil and capacitor in "boost" configuration -- or as a classic push-pull
    switching supply.

    fwiw, I have an ancient Genrad sound level meter which uses discrete
    transistors and a torroidal transformer (about the size of your pinkie
    fingernail) to drive all the electronics from a couple "C" batteries.

    It's much less expensive, much less noise generating to use an off-the-shelf
    switching regulator chip -- and these are almost as inexpensive as a
    ULN2003.
     
  7. Erwin Thomas

    Erwin Thomas Guest

    How much voltage would you like..16V. Other considerations would be
    regulation, power, ripple. Yes you can make multipliers from just about
    anything that produces a changing voltage. Transformers are a popular
    method, series or parallel multipliers using capacitors are another. The
    ULN2003 configured for parallel multiplier that provide lower ripple and
    output impedance. To reduce ripple even more some phase shifts would be
    necessary, regulation could be improved by a adjustable regulator. The
    series multiplier easier to construct may be the way to go, since you could
    tie ULN2003 outputs together to drive. All of these circuits can be found on
    the internet, but must be adapted.

    Good luck
     
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