Ok, so first off I'd like to apologize if this has been answered before. I did my best to search the forum, but all I could find were the solutions that I couldn't use.
So my problem is one that has cropped up every other day, and that is that I need a 12V digital array. So I want the arduino 5V to turn on an external 12V logic. The problem is that every transistor switch I've seen really just switches in the return to the load.
I do not have access to the load. I am controlling an array of 8 logic pins which are in reference to case ground inside of the case. This means I need to have the switch drop in the +12, rather than having it be hot all the time. Simply put, I need the switch to be on the other side of the load - is this possible with a simple transistor switch?
Thank you for any assistance offered!
Yes, do a search on the term 'high-side switch'. This usually involves using P channel mosfet or PNP transistor to switch on and off a positive voltage wired to a ground based load.
Here is an article on using a PNP transistor circuit to implement high side switching from a uP digital output pin like an arduino output pin.http://www.w9xt.com/page_microdesign_pt8_pnp_switching.html
Of course a good old fashion relay can accomplish the same task.