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I am making a circuit to control a motor using an Arduino UNO and an H-bridge IC, but it's not working, rather something strange is happening.

Circuit's scheme: scheme for my circuit

When the motor is connected to pins 3 and 6 of the H-bridge nothing happens, but strangely when one of the motor's wires is connected to either 3 or 6 pins of the H-bridge, and the other wire of the motor is connected to ground the motor works! But I can't control it's speed with the potentiometer, neither control it's direction, or even it off using the push-buttons.

I suppose that the H-bridge deliver power to it's 3 and 6 pins because the motor works when connected to ground and one of them, but this shouldn't happen, one of the pins (3 and 6) should deliver power and the other should be ground, that's what I think.

How can I solve this problem?

Edit: For some reason the wires connecting Arduino pin 2 with H-bridge pin 7 won't deliver 5 power unless I was touching the wire with my finger, (this also happen in the wire between Arduino pin 3 and H-bridge pin 2) I've tried connecting the pins with other wires, but the same thing happens, also I've used an 220Ω resistor and the problem is still happening. this thing happens with all Arduino pins, not just 2 and 3, but in before this project they were working very well. O_o

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  • \$\begingroup\$ The L293D is an ancient, horribly lossy part and performance on a mere 5v supply will be absolutely terrible. You may well have an additional problem, but even when "working" the results will not be pleasing. You should 1) use a motor supply that is not the Arduino's 5v rail, 2) use an FET bridge not a darlington one like the L293/L298 and 3) verify that all connections are correct both theoretically and as actually built \$\endgroup\$ – Chris Stratton Jan 11 at 18:59
  • \$\begingroup\$ ... and then verify that the chip inputs and outputs are working. If you still have problems you will have to look at (1) the wiring between the microcontroller and the driver and (2) your code. \$\endgroup\$ – Transistor Jan 11 at 19:01
  • \$\begingroup\$ I made sure everything was working (except H-bridge internal connections), so the problem is absolutely from the H-bridge itself? \$\endgroup\$ – Azzam Alsharafi Jan 11 at 19:04
  • \$\begingroup\$ Or from the assumption that you can reasonably use this H-bridge chip at 5V. \$\endgroup\$ – Wouter van Ooijen Jan 11 at 19:25
  • \$\begingroup\$ @WoutervanOoijen what do you mean? Is 5V low or high for H-bridge? \$\endgroup\$ – Azzam Alsharafi Jan 11 at 19:27

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