Please make corrections to my project schematic!

[thekyguy11]

I am building a device to replace the ignition switch on my car. I have already written the code for the PIC18f1320 (thanks to everyone who has helped me so far), and I have attached my schematic that I drew up on Express Schematic software. I'm kind of learning as I go, so I figure there has to be at least a few "Rules of thumb" that I am violating with this. Plus, there are a few values that I am not sure of. I also attached the LM2917 data sheet and the diagram I got the LM7805 setup from.

R4,R7- Inputs to PIC, from what I understand, its ok that its 12v, as long as there is a resistor... I just don't know what value this resistor should be.

C4- The LM2917 **broken link removed** (page 8, "Speed Switch) doesn't say anything about this capacitor in the picture.

C5,R9- I believe these control what input RPM will activate the output of the LM2917. I'm shooting for 350rpm, but thats just a guess. I'll need to do some testing to find out.

Also, Are the pins I chose to connect to on the PIC acceptable? Do I need to connect any more?

 

[be80be]

I use a voltage divider with a 10k and a 8 k your using it as input that would give 4.9 volts

 

[thekyguy11]

I'm not sure what you mean...

Here is an updated schematic.

 

[be80be]

A picture show you better
This gives you 1.2 Milliamps at 4.9volts on your

R4,R7- Inputs to PIC, from what I understand, its ok that its 12v, as long as there is a resistor.

 

[thekyguy11]

I get it, thanks. I will implement that. See any other problems? Do I need to use pull up/down resistors for the PIC inputs?

 

[be80be]

I would put some capacitors across the coils of your relays