Protecting circuit to IO card from surge

[ethan_oost]

Hi
I am new to electronics. I am building a simulator connecting switches to a computer via a microcontroller IO card (I use a pokeys card) So one wire goes to ground on the card and one to a free digital input port. It works well. The problem is this.. One switch has a built in solenoid to automatically flip the switch off. This solenoid requires a 5V charge and created a current of about half an amp to switch. The switch has only 2 pins, so it uses the same pins for the switch logic and the solenoid connection. This means that when I apply the 5v 0.5A charge to activate the solenoid, I am effectively connecting the digital input of my pokeys card to the same circuit. I don't think that is good. It will be only for a short time frame as the switch will automatically turn off when the solenoid fires. How can I protect the IO card from getting fried? Anybody has any ideas. Thank you
Ethan

 

[Arouse1973]

Can you supply a circuit diagram please so we can see what you intend to do. I understand it's difficult sometimes to explain what you want to do so a diagram lets everyone else understand fully what you might need.
Adam