I'm looking to buy a small device that does a simple task. When this device gets the signal is rotates to a set position. So what I've been told is that something called a servo does the trick, but looking into it it seems that a servo might do a little more then what I need. What I need is a device the only rotates to 2 positions an OFF default position and an ON set position. A servo seems to be able to rotate to any degree I wish, which i believe might add some bulk to the device. Trying to keep this device small so hoping maybe there's a better device for my issue.
Sorry for my lack of grammar in this field, I can understand that it could be frustrating, but I'm trying and learning:) If I'm not being clear or you have any questions I's be more then happy to answer.
Servos are one of the easiest things to control with an Arduino. With a solenoid you will almost certainly need to add a transistor and some resistors to link it to the Arduino.
Some of the servos are very small - and cheap. I have some that measure 22x30x12 mm and you can get them much smaller than that. Have a look on the HobbyKing website.
Well a small servo is probably easier to use, but it will not have a 'default position' that it moves to when you power it off, you have to command it to every position required before removing power. A solenoid has a internal spring to establish it's 'default position'. A solenoid however does require you use a switching transistor to supply the current it requires as it's more then a output pin can provide.
I need this to create a physical locking mechanism. So a simple example would be when the device is rotated to 0 degrees then the machine is unlocked physically, when the device is rotated to 90 degrees then the machine is locked. Id like it to be able to switch between the two pretty quickly. Also what I'm building needs the device to be pretty small and mobile. The smaller the better but I'll take what I can get.
A small servo should be very suitable. If you need a physically strong lock you could perhaps use a standard metal bolt (brass or steel) that is moved by the servo.
How will your device be powered? If you use batteries you may need an arrangment to cut power to the servo (the positive connection, I believe) when it is not actually required to move. A small transistor controlled by the Arduino should make a suitable power switch.
I was hoping it would be powered by USB, although I will need 5 of them on one device, so not sure if that will work. Im still very new to creating physical output devices, so it will be a long road ahead. Any words of wisdom?
You can't power even one motor (servo or any other) through the USB connection - it will draw too much current and may damage something. The motors will need a separate power supply that can provide the amount of current required by the motors. Servos generally need 5v or 6v and you should allow about 1 amp for each servo.