For some context, I want to create something like this. For now, until I change my chips (which I know I need to do as a plan to use a lower voltage Vcc2) I'm using the sn754410 h-bridge IC, 74HC595 Shift Register. I find that using two of these ICs (a total of 4 electromagnets) results in almost all of my digital I/O Arduino pins being in use. I'd like to use about 8+ of these h-bridge ICs (that would be 48+ I/O pins for the 8+ h-bridge ICs) but I don't know how I could do so while also maintaining a full duty cycle current (complete on 100%) at times needed.

My question would be what can I use to achieve this and still have the option to have a bunch of inputs on HIGH all at the same time (or really close to each other where they seem to have turned on all at the same time to humans)?

It seems like shift registers may have a PWM effect on the pins (clock?). Do shift registers have a PWM effect on the pins, therefore reducing the current going into the output of the h-bridge ICs?

  • \$\begingroup\$ I noticed that you'd not "officially" accepted an answer on your previous question here: electronics.stackexchange.com/questions/208720/… - now maybe you didn't understand my answer or maybe you didn't know that answers fulfill/explain things can be officially accepted. Anyway maybe you can let me know? \$\endgroup\$
    – Andy aka
    Jan 8, 2016 at 22:58
  • \$\begingroup\$ I will wait for the above to be sorted out before I attempt to answer this question \$\endgroup\$ Jan 8, 2016 at 23:09
  • \$\begingroup\$ @Andyaka I think I understand two things: The higher the current of the load, the more of a voltage drop is experienced from the output. Also, the minimum Vcc2 is 4.5V which means that the chip is terrible especially for low voltage applications and especially for when there is a need to drive 0.5A+ (you said 100mA, but I don't understand that part). I thought I did accept, but should be fixed. \$\endgroup\$ Jan 8, 2016 at 23:14
  • \$\begingroup\$ Have you considered using a haptic driver? \$\endgroup\$ Jan 8, 2016 at 23:30
  • \$\begingroup\$ @IgnacioVazquez-Abrams You mean instead of whatever I'm doing? I actually did not consider them/do not know anything about them. I did watch this video youtube.com/watch?v=y5nf-8N7J7g I'm assuming that the haptic driver is best with something like a screen? \$\endgroup\$ Jan 8, 2016 at 23:55

1 Answer 1


some serial in,parallel out shift registers eg:74HC595 have a latched output so that during updates there need be no flickering of the output, just load all the registers up and then pulse the latch clock.

one the latch pulse comes the outputs will stay the same until the next latch pulse.

  • \$\begingroup\$ I'll try out the circuit wiring again and get back to you. \$\endgroup\$ Jan 9, 2016 at 13:16

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