L298N board on 24V blows connected arduino Uno. Work on 12V

Other Hardware Motors, Mechanics, Power and CNC
1

I have a L298N based H-Bridge from Ebay. It is a China produced "widget".
http://www.ebay.com/itm/Dual-H-Bridge-DC-Stepper-Motor-Drive-Controller-Board-Module-L298N-for-arduino-/400352973895?pt=LH_DefaultDomain_0&hash=item5d36e59447

I wire the L298N board the same way as the http://arduino.cc/en/Main/ArduinoMotorShieldR3.

When I operate the L298N board with 12V everything is working. I made a testprogram that makes my robot do a squere from speed 0 to Speed High using PWM turning both clockwise and anti-clockwise
.
The PWM is connected to pin D3/D11.

When I connect to 24 V everything is working to start with.. After a while the L298N gows BANG!!! Smoke and Fire!! The problem is that it also blows tha Arduino Uno.

Looking at the diodes they only say "M7".. Looking at "M7" the only thing I find is IN4007.. This is far away from the fast recovery diodes needed for L298N to take care on the inductans created from the motor. Could it be the PWM and the switching loosses that Fries the L298N or is it the diodes that is could be the blame.

Could it be a PCB board design and diode selection to only create forward and backvard motion without PWM? The result of just doing Forward/Backward with fullSpeed will just create one inductans pulse on each direction change.

I have blow 2 Arduino Uno :frowning: and wants to know why

2

Did you read the notice in the link you posted?

2.This module can use built-in 78M05 for electric work via a driving power supply part.But to avoid the damage
of the voltage stabilizing chip,please use an external 5V logic supply when using more than 12V driving voltage.

Lefty