July 4, 2010

Drive High Current

To let my new RFID reader drive one electric bolt (or more!) I need a circuit to handle relative high current when a valid fob is recognized (thus having a logic +12V output on a pin on the RFID board). Both the reader and the bolt work at 12V DC.

Here is a simple schematic circuit (with parts list):

Here is the physical layout of the main components from their datasheet:

Here is the breadbording (simulating logic input with a temporary switch):

Here is the realization schema on a stripboard:

And here is the board:

Probably the heat sink is useless, due to the typical current flow in the electric bolt (only very few seconds maximum, during unlocking), evenf if I plan to use it to contemporarily unlock a set of electric bolts on a large port (for enhanced security). By the way, it was laying around after some salvaging from old electronics...

Now my RFID Electric Bolt is completed.