H-Bridge for polarized pulses. Components for 24V and 12V low voltage cutoff.

Discussion in 'General Electronics Chat' started by Johanpp, Jan 5, 2016.

  1. Johanpp

    Thread Starter New Member

    Jan 5, 2016
    11
    0
    I used parts of working schematics and adapted them for a new project. I am very new at electronics, but trying my best. I think I've made a new schematic which could work, but I have questions.

    This board receives a pulse from an Arduino Uno V3 board every 60 seconds and in turn supplies a polarized pulse to the slave of a Slave and Master clock in a tower.

    I would like the final board to work for either 12V or 24V, depending on the particular Slave's voltage. I will fit the correct components depending on voltage.

    2 Now, the 220uF 25V Cap works fine for 12V. Should the Cap be doubled for 24V?

    3. Where Batt is indicated it could be 12V or 24V.

    The polarized terminals T7 swap polarity for every 60 second pulse. The pulse is supplied by Arduino Uno V3 which in turn uses GPS as an accurate time base. Arduino will send the 60 second pulse alternatively to T6.1 or T6.2. Arduino receives 10V from U4, Terminal 5.

    The left side of the schematic is the H-Bridge with some switches T3 and T4 that will aid setting the correct time and

    some LED's to help setting up etc.

    The right side is to cut all power should the Lead Acid battery stop charging and voltage drops below a safe voltage.

    I attach the schematic. Maybe you can have a general look at the schematic to identify more problems.

    I sure will appreciate your help.

    Regards
    Johan
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,985
    745
    I would omit Q4,Q5 and input direct to Q1,Q2 also opamp U3, only needs one half and use it as a schmidt trigger by inputting at pin 3, and reference on pin 2, and putting hysteresis on it to prevent pulsing.

    What is the input battery voltage, because your already using 24v regulators?
     
  3. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    How does LD2 or LD3 ever illuminate?
    What is the dropout Voltage for U2?
    The H-Bridge can source/sink a max of ~100mA. Is that what you intended?
    What prevents the Arduino inputs 3,4,5,6 from being pulled above 5V?
     
  4. Johanpp

    Thread Starter New Member

    Jan 5, 2016
    11
    0
    Hi Dodgydave, sorry about the delay replying to you. My setup must be wrong as I did not receive notification of replies from anybody. I now found this reply by chance. Thanks for your interest.

    Yes, I could skip Q4 and Q5, will try that.

    You say "also opamp U3, only needs one half and use it as a schmidt trigger by inputting at pin 3, and reference on pin 2". I am not sure what you mean by this.


    I need 24V to trigger the slave of a public clock in a tower. LM7810 reduces the voltage to 10V to power Arduino V3 which will pulse Q4 and Q5 alternately to change the direction of the flow of power to achieve polarization. It is a 200ms pulse.

    Thanks again.
     
  5. Johanpp

    Thread Starter New Member

    Jan 5, 2016
    11
    0
    Sorry about the delay replying to you. My setup must be wrong as I did not receive notification of replies from anybody. I now found this reply by chance. Thanks for your interest.

    U2 will reduce the charger and battery voltage (at times as high as 30V) to protect the components on the main PCB and to reduce the heat generated by U4.

    The H-Bridge is part of a working PCB which energizes a coil drawing 1amp and in another application a DC motor, also 1amp, but starting current way above that.

    I have already discovered my problem with the unconnected pins and now use: As of Arduino 1.0.1, it is possible to enable the internal pullup resistors with the mode INPUT_PULLUP. Additionally, the INPUT mode explicitly disables the internal pullups. This seems to have sorted out that problem.

    Thanks again for your interest.
     
Loading...