Pulsed Output From 8 Data Lines To Drive A Solenoid

Discussion in 'General Electronics Chat' started by JohnnySH, Jul 17, 2014.

  1. JohnnySH

    Thread Starter New Member

    Jul 17, 2014
    1
    0
    Hello

    Ok so I have 8 x 5 volt data lines that each line can either go between either 0-5v and 5-0v

    I would like to drive 8 solenoid coils from my 8 data lines. My requirement are as follows

    1) High current drive, Approx 500 milli amps
    2) High voltage, above TTL logic, Approx 14 Volts DC
    3) When Data Bus levels goes from low (0v) to High (5V) Solenoid Coil is engendered for about 500msec
    4) Minimal components used, thus keeping cost and size of PCB low and small sized

    I hoping someone can suggest the best practice to achieve my above requirements, I want to drive 8 12volt solenoids from a data bus, and energize each solenoid when each data bus line level goes from low to high, for about 500ms using the very least amount of components.

    I am planing to use a darlington 8 channel driver IC in between the data bus and the solenoids, this gets over the high 14 volt and 500 ma per channel, It also has internal protection diodes to prevent damage from back emf high voltages from the solenoid coils. So most of the problems have been solved from this IC.

    The only problems I see is being able to generate for each of the 8 data bus channels a pulsed output drive to energize the solenoid coils, obviously if I leave the drive to the coil permanently, I may end up burning out the coil and pulling lots of unnecessary current. So a pulsed drive of about 500ms - 1 Sec should be fine.

    Would just like to find the least complicated and least expensive way to achieve this using components, (NO Micro)

    Maybe a CR network, or they may even be some 8 channel timer IC to do what I want, any advice will be very much appreciated.

    I am not interested in the signal going from High to Low, I don't care about that, Only From Low to High and staying high for (X) amount of time for each of the 8 data lines.

    any help in this quest as always is much appreciated in advance

    Regards

    John
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,979
    3,704
    Why will the coil burn out? Why not get a solenoid that can handle the power? ... Or, more importantly, dump the heat... Or, has higher DC resistance.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,498
    2,364
    ULN2803 all though the current is at the limit, they do also have internal BEMF diodes.
    If these are pulsed solenoids, it sounds like the magnetic latching types?
    Generally these are not harmed if the current remains.
    What is the type of control used to pulse them?
    Max.
     
  4. crutschow

    Expert

    Mar 14, 2008
    12,974
    3,220
    You could probably use an RC circuit to give the one-shot pulse signal.

    What is the 8-channel driver IC you plan on using?

    What is the repetition rate of the signals?
     
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