Killed my arduino with a bost converter?

Hello.

I was setting up a quick project and needed to power a cheap chinese Arduino nano with a 3.7V battery, so I got a cheap boost converter step-up. I adjusted its voltage to around 8V and connected it directly to the Vin Arduino pin.

I was also using an H-Bridge IC (L293D) for controlling a dc motor, which was also being powered by the 8V output.

The circuit worked fine until the motor started, which fried my Arduino. The L293D has protection diodes so I don't think it was related to EMF. (I've used this H-Bridge many times before and never had a problem).

I suspect that whenever there is a current peak on the boost converter, there is a voltage fluctuation (positive and negative) on its output, which is killing the voltage regulator and then the 328P. Since I don't have an oscilloscope, I can not confirm. Have any of you experienced something similar?

I thought maybe adding a large capacitor on the output could solve the problem, but I'm not willing to try since I'm not sure if that's the problem.

I found another topic with a very similar problem: https://forum.arduino.cc/index.php?topic=628916.0

Anyway, sorry if I said anything dumb, I'm still sort of a beginner on the topic.

Thank you and happy 2021!!

Before you think of anything else, get a digital volt ohm meter (DVM) so you can measure, not guess.

Paul

I adjusted its voltage to around 8V and connected it directly to the Vin Arduino pin.

That wastes about half the battery power. The on board regulator converts the 8V back to 5V by dumping heat.

It is much better to use a 5V boost converter, and power the Arduino through the 5V pin.

The L293D has protection diodes so I don't think it was related to EMF.

The destruction was certainly due to the electrical noise (EMF) generated by the motor. The voltage spikes get dumped into the motor power supply, which fries the Arduino on board voltage regulator, and possibly also the boost converter.

Always power motors and Arduinos separately, but don't forget to connect the grounds.

Guigosoldadinho:
The circuit worked fine until the motor started, which fried my Arduino. The L293D has protection diodes so I don't think it was related to EMF. (I've used this H-Bridge many times before and never had a problem).

I suspect that whenever there is a current peak on the boost converter, there is a voltage fluctuation (positive and negative) on its output, which is killing the voltage regulator and then the 328P.

Hard to say what exactly happened at the moment. Any specs associated with the motor you're using?

Hi,
Can you post a circuit diagram showing how you had your project connected?
Please include powersupply and gnd connections as well as the motor.
A picture of your project would help too.

Thanks.. Tom.. :slight_smile:

FYI, you are not supposed to power an L293 motor driver with the 5V power supply that powers the arduino.
(for many reasons)
What was the output voltage of the boost converter AFTER the alleged damage ?
Define 'fried'

The destruction was certainly due to the electrical noise (EMF) generated by the motor. The voltage spikes get dumped into the motor power supply, which fries the Arduino on board voltage regulator, and possibly also the boost converter.

I think the jury is still out on that. We haven't seen a schematic and it's possible it was a miswire.
(8V connected to 5V )
We haven't seen any FA data yet. I've used the L293 many times and as long as the motor power is separate
from the logic power there should be no problem. I seriously doubt motor spikes on the INPUT of a 5V regulator
would damage it. (for several reasons) although clearly using motor power for logic power regulator input is bad
practice.
FYI, not that it matters but it's 'BOOST' converter, not
'bost'.

Sorry for the ridiculous diagram, all I could do for now. I forgot to mention, I had a voltmeter hooked to the booster output all the time, but only notice a ~0.1V drop when turned the circuit on.

Define 'fried'

Arduino stopped responding, voltage regulator and 328P got burning hot. L293D and boost converter are still fine.

Edit:

Motor: 12V DC scavanged from an old printer. Its shaft had no load.

+5V comes from Arduino's regulator.

I had everything soldered, no protoboard. Double-checked continuity on every connection before turning on;

After killing it, the 5V regulator input and output are shorted.

Vcc 2 = Vmotor.

The project: I'm trying to build a box that corrects itself when thrown in the air with a reaction wheel and a gyroscope.

Guigosoldadinho:

Sorry for the ridiculous diagram, all I could do for now. I forgot to mention, I had a voltmeter hooked to the booster output all the time, but only notice a ~0.1V drop when turned the circuit on.

Don't ever apologize for a schematic. I will take this over a silly Fritzing picture anytime.

Are you driving a motor from the Arduino? That would be wrong and could fry the regulator on board.

Adafruit (and in this case, Simon Monk) show things as you have done.

The L293D uses Arduino 5V for housekeeping and so on. Its pin_8 is for V_motor.

RP ------ thanks for that link. If I were to have a word with Simon ..... (who I don't know heheh) ....... I'd tell him to provide at least some specs for the motor he used ------ and the parts list in his article says 'small 6V DC motor'.

Despite the spec of that board saying:-

Maximum Output Current: 2A

There is no way you can get anything approaching that sort of current from one. The maximum current you can get depends on the ratio of input voltage to output voltage.

In my experience I have never got more than 600mA output with a times two boost.
My guess is that the current was too high for the board and the output collapsed in some way, causing a reverse voltage to be applied to the Arduino. That is a very good way of making the 328P hot.

I thought maybe adding a large capacitor on the output could solve the problem, but I'm not willing to try since I'm not sure if that's the problem.

It can do no harm, but I would not use that boost converter, especially as you don't know the stall current of the motor. Find this out by measuring the winding resistance and using ohms law to calculate what the switch on current will be.