This is part of an automotive timer (NOT a 555!) that we have at work. Because I'm extremely bored I'm challenging myself to understand how this one operates. I've spent about 1.5 weeks with tutorials, brushing up on my transistors, flip flops, electrostatics and such. My area is RF not power and this is extremely difficult for me. I tried as best as I could and it's keeping me up at night.
I know that a BJT needs to have a base voltage to turn on but this one's base is connected to the inputs of a NAND gate as featured in the pin out of the IC. (a CD 4011BC) There are a number of other connections but I haven't drawn them here to keep things simple. The emitter is connected directly to a relay coil and the approx measured voltages are listed on the paper. The collector gets +12V in and the base is connected to pins 13 and 12 which are inputs into a NAND gate on the IC.
I do not understand how this device is able to run. I don't have all the pin-outs drawn on this picture but I do have it elsewhere. I wanted to focus on how the bjt can even turn on if there's no (what I assume to be at least) base voltage or current. It does run though, and times correctly. From what I have learned it's in the active region of operation. Please help!
Editing to add another picture. Note that the drawing differs slightly from the picture due to connections running under the IC. The dot on the IC is at the top left, so the 1-7 pins are on the left side. I drew it the way I did to make it easier to visualize as, of course, traces are all over. I can redraw this if necessary. Also, the stuff on the caps is melted rubber band goo, not exploding cap goo.