How to put on fly-back diodes on Arduino and transistors revers able motor driver ?

Thread Starter

LAOADAM

Joined Nov 21, 2018
862
Attached drawing shown Arduino and transistors revers able motor driver, I put two fly-back diodes there but looks not feeling very well, is that the way should be? is it right to delay between two pins shift?
Thanks.

post100.JPG
 

cmartinez

Joined Jan 17, 2007
8,220
Attached drawing shown Arduino and transistors revers able motor driver, I put two fly-back diodes there but looks not feeling very well, is that the way should be? is it right to delay between two pins shift?
Thanks.

View attachment 181785
Are you trying to build a reversible motor driver? Because with the diodes arranged that way, the current will short circuit, damaging the transistors and quite possibly affect the power supply too. Plus the motor won't run.

What you need is an H-bridge configuration to drive the motor. Google it up.
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
862
Are you trying to build a reversible motor driver? Because with the diodes arranged that way, the current will short circuit, damaging the transistors and quite possibly affect the power supply too. Plus the motor won't run.

What you need is an H-bridge configuration to drive the motor. Google it up.
Thanks.
Yes, I am try to make a simple bridge, a small motor, i tried test without diodes, it's OK. can I just remove the diodes?
 

cmartinez

Joined Jan 17, 2007
8,220
Thanks.
Yes, I am try to make a simple bridge, a small motor, i tried test without diodes, it's OK. can I just remove the diodes?
You need to re-evaluate the entire circuit, as kubeek just said.

Here's the basic configuration of a basic H-bridge circuit, for your consideration:

Image00001.jpg
 

Thread Starter

LAOADAM

Joined Nov 21, 2018
862
Arduino-DC-Motor-Control-using-L298N-H-Bridge-using-Transistors.png
You need to re-evaluate the entire circuit, as kubeek just said.

Here's the basic configuration of a basic H-bridge circuit, for your consideration:

Thank you, I used the same circuit as your picture here, except D1 - D4, don't know why it draw too much current even without trig yet. I used two 7805 convert 12V to 5 V as power supply to the bridge that become very hot. I used two BD139 + two BD140.
 

MrAl

Joined Jun 17, 2014
11,389
You need to re-evaluate the entire circuit, as kubeek just said.

Here's the basic configuration of a basic H-bridge circuit, for your consideration:

Hello,

I might add that the power source line Vcc must have an impedance low enough to absorb the energy from the motor when the motor pushes current up through the top diodes. That recycles some energy, but if the Vcc supply impedance is too high it will force the voltage Vcc up too high and thus cause something else to burn out. Remember the motor inductance makes it look like a boost converter for some modes of operation.
Usually there is adequate capacitance on the Vcc to ground buss.
 

cmartinez

Joined Jan 17, 2007
8,220
Hello,

I might add that the power source line Vcc must have an impedance low enough to absorb the energy from the motor when the motor pushes current up through the top diodes. That recycles some energy, but if the Vcc supply impedance is too high it will force the voltage Vcc up too high and thus cause something else to burn out. Remember the motor inductance makes it look like a boost converter for some modes of operation.
Usually there is adequate capacitance on the Vcc to ground buss.
Oh, I'm aware of all those considerations. I'm only trying here to guide the OP through baby steps.

View attachment 181829

Thank you, I used the same circuit as your picture here, except D1 - D4, don't know why it draw too much current even without trig yet. I used two 7805 convert 12V to 5 V as power supply to the bridge that become very hot. I used two BD139 + two BD140.
What are the exact specs of the motor you're trying to run?
 

dendad

Joined Feb 20, 2016
4,451

This will only work if the A and B inputs swing to the full supply volts level. You cannot , for instance, run the motors off 12V and the driving signals between 0 and 5V. They must be 0 to 12V in that case.
 
Top