Arduino "DO NOT'S"?

Hi there,

I have my new Arduino Diecimila and want to know if there are any pins which should not be connected directly to each other?

For example the 5v pin with any of the I/O pins.

Thank you

usually you would not connect the pins directly to each other, but put something in between, like switches, resistors, potentiometers and so on.

If you want to read a switch, you would connect an i/o (i) pin to 5V but with a pull down (or up) resistor.

But it’s really a bad idea to connect the + 5 volt pin to the ground pins. It’s also a bad idea to try to source more than 40mA from any pin on the board by for instance trying to run a DC motor or relay directly from a pin.

If you are very new to Arduino and electronics i general Lady Ada’s tutorials come higly recomended.

oops, i think i ran a 5 or 12v motor on the ardion, connected to 5v and gnd, it looked like it drained the power cuz everything turned off after the motor ran for a few seconds, but i can reccomend any motor that uses more then like 3 volts tops, cuz it drains the power source!

Any inductive load (motors, relays and solenoids) should be connected through a darlington transistor like TIP 121 or similar.
And the load should have it’s own powersupply.

Even the smallest DC motor pull a lot of current when it starts up.

i was able to run a very small motor off pwm though, but the motor is smaller then the area of a quarter…

Well that would be the exception that confirms the rule :slight_smile:

There are probably very small motors that do not draw more than 40 mA. Maybe some of the little vibrating motors from pagers and cellfones fall in this category as well.