Hi I have a project to complete for my university. I amdesigning a PDA controlled vending machine. I have made a program on Labview for the PDA. Now when the user opens the software and stands infront of the vending machine he will scan for vending machines.whatever he wants he then selects that vending machine. the vending machine will have buttons corresponding to 3 slections. When the user selects the button,the microcontroller in the venidng machine will send a signal to a computer that will also be connected to themicrocontroller. If the person has enough balance the microcontrollerwill turn the correspoind motor on so it can vend the item. the motor is24 VAC. the microcontroller also needs to be connected to a bluetoothtranceiver. My question is that I am looking for the rightmicrocontroller that can be able to turn on one of the desired motors. Iwill connect each motor to the microcontroller though a relay. could youplease guide me how to od it.
These relays have an opto isolator built in to the relay. The relays come in AC or DC. You need AC for the AC motor and DC control to connect to the microcontroller. There are relays with sensitive inputs (lower power), but you still might need an npn transistor to turn on the relay. The microcontroller is not critical, use whichever one you want to. The I/O pins need to be able to control the Solid State Relays (perhaps with a transistor).
I'd first put an opto-isolator between the output of your controller and the relay. You can probably find an opto-isolator / relay combination that will work with just one relay, or you might need two relays. Opto-22 makes output relay modules that might suit your need.
Use a relay triggered by an output pin on your uc. You might need to boost the current with a transistor amp enough to actuate the relay.
Since you have the relay isolating the motor current from the controller, it's trivial. Just use a transistor or Darlington junction to amplify the control signal to a large enough level to drive the relay, and you're done.
