i need diodes to protect the arduino and the relays of course..Diode branch is OFF (Not working)
why you need Diode?
- Don't pay attention to the pwm, consider it as a standard I/O ('1' or '0').Hi,
If you say it works, then that is good. I don't understand how the circuit operates.
What does each Arduino PWM pin do?
What does each relay pin do at forwards and at backwards?
How do the diodes protect the Arduino and the relays, placed where they are cathode to cathode around the motor?
Eventually will one diode or the other diode break down with the reverse motor current it must have to block every time the motor changes direction?
The two diodes you have do nothing since they are connected back-to-back and cannot conduct in either direction unless one of them breaks down. It would work if the two diodes were Zener types.
To protect the relays from back EMF for a reversing motor using standard diodes, you need two pairs of diodes in series.
Connect each pair between the supply V+ and V- (anode of the bottom diode to V-).
Connect the junction of one pair to the top of the motor and the junction of the other pair to the bottom of the motor.
are you sure that these are not TVS diodes , they look the same as normal diodes . what is their part number ?
A question:
What is the diode's part number?
I agree 100% with Crutschow: if they are normal rectifier diodes, they don't do anything. Ever. They are connected back to back and one will always block the opposite one.
Now, if they are breakdown diodes like zeners or Transorbs, that is another story. But we need to know the diode's part number.
I'm referring to whatever power supply is powering the motor through the relay.but the motor is not connected directly to V+ and V-..i think that i didn't understand what you mean very clearly..could you draw it for me on the circuit above?
In Post #5 he said he has a ULN2003 driver IC between the Arduino and the relay coils and it has suppression diodes in it.now i noticed something , there is no mension whether there are diodes on the coil of the relay ? these will affact the circuit more than those across the motor . provide a schematic or photo or the circuit , not just a block diagram
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