H Bridges and Arduino programming - Preventing shorts.

Hello,

I am currently trying to build my first H-bridge consisting of four NPN IRF520 transistors and four 1N4001 diodes. So far, so good.

However I am somewhat worried regarding the possibility of causing a short if the H-bridge inputs are not correct.

I know Arduino sends some random values to the pins while its being programmed and can possibly cause damage to the circuit so I was wondering if there was a way to prevent that from happening?

Thanks !

I am currently trying to build my first H-bridge consisting of four NPN IRF520 transistors

How do you do the high-side switching with N-Channel MOSFETs?

I am somewhat worried regarding the possibility of causing a short if the H-bridge inputs are not correct.

Many commercial H-Bridge circuits use internal logic to prevent the high-side and low-side MOSFETs from turning on at the same time. For the Arduino, most of the pins default to INPUT so you can use pull-up and pull-down resistors to set default values. Be use to do digitalWrite() before pinMode(,OUTPUT).

You can but H-Bridge chips that connect to external MOSFETs of your choice.

Poster child discussion for DIY h-bridges.

johnwasser:

I am currently trying to build my first H-bridge consisting of four NPN IRF520 transistors

How do you do the high-side switching with N-Channel MOSFETs?

I am somewhat worried regarding the possibility of causing a short if the H-bridge inputs are not correct.

Many commercial H-Bridge circuits use internal logic to prevent the high-side and low-side MOSFETs from turning on at the same time. For the Arduino, most of the pins default to INPUT so you can use pull-up and pull-down resistors to set default values. Be use to do digitalWrite() before pinMode(,OUTPUT).

You can but H-Bridge chips that connect to external MOSFETs of your choice.

I assume I can connect them the other way around so I do not need a couple PNP ?

Also, what value should I set the pin to? Low?