Motor

Forum 2005-2010 (read only) Hardware Interfacing
1

I need to run a motor, and my arduino can't provide the juice. So you say, a MOSFET! But I don't have any. (Shame on me) And I need it NOW!!!!
Can I do this to get more current?:

And by changing P2's state, I could have a transistor of sorts...?

2

  1. Motor runs fine off Arduino 5V and GND. I just want to control it.

  2. I do not have ANY transistors. I can buy some and they will be here by Thursday, but I want to do it now.

  3. I do have this:
    TC4069UBP_07 pdf, TC4069UBP_07 Description, TC4069UBP_07 Datasheet, TC4069UBP_07 view ::: ALLDATASHEET :::

What if I fed +9V into the inverter from a 9V battery, an then, If I left one of the inverters LOW, it would output 9V! There are transistors inside the inverters, so I can just use that.

3

In an ABSOLUTE pinch, I'd drive all six of the inverter input with one arduino output pin. Then attach the motor to +9v (or whatever your source for the motor is) and the other end to all six of the inverter outputs.

This may break the inverter but its safer than just driving it from the arduino and six outputs in parallel can sink more than one inverter can (but less than six, they wont load balance).

Also check the datasheet (i can't read the link you posted) to see if the inverter will run on 9v.

lastly for one of the reasons why your original circuit won't work see:

4

You have run the motor at 5vdc and it runs. Ok so now you/we need to know how much current the motor draws when running at 5vdc. Once we know that we can ponder possible solutions. However until you know the current value do not wire the motor directly to an Arduino output pin. I you don't have the time to wait for a transistor, you probably won't have the time to wait for a replacement AVR processor chip either?

So break out the old trusty digital multimeter. If you don't have one then before you order anything else, order a meter. They are pretty cheap and no one has any business building stuff with an Arduino without first getting and learning to use a multimeter.

Lefty

5

I do not have ANY transistors. I can buy some and they will be here by Thursday, but I want to do it now.

If you are in the US, go to radio shack and get a power transistor.

6

It's drawing 100mA from 5V/GND.
Would the inverter work?
Also, could I string multiple digital outs in parallel like this

Pin 2 Pin 3
| |
| |
_____________________(Motor)----GND

to get more current?

7

It's drawing 100mA from 5V/GND.
Would the inverter work?
Also, could I string multiple digital outs in parallel like this

Not at that current level. It would take 5 output pins operating each at 20ma each to work, but using the normal digitalWrite() commands wouldn't be fast enough to insure there isn't short circuit currents flowing between pins until they were all at the same output value. Also there are not enough pwm output pins to be able to share this current load, nor is the pwm analogWrite designed to use parallel output pins if you wished variable speed control for the motor.

There is no getting around requiring a transistor to perform the output switching for the motor. Don't forget the series base resistor required between the output pin and the base of the npn transistor.

Lefty

8

Would the inverter work? (string all 6 together to get a non-inverted output?)