Is this simple schematic electrically correct?

[sccoupe]

Is the attached schematic electrically correct for an automotive environment? Press the switch and the LED comes on. Im doing some testing and this works but is it correct? Anything out of wack or incorrectly done?


Thanks all.


It appears that this should be moved to the schematics section of the forum.

Thanks

[Charles Linquis]

No, There are at least three mistakes:

#1. You need some capacitance across the the power supply leads of the PIC and at the output of the regulator. I recommend a 10uf and a .1uf in parallel.

#2. Pin 4 will never go LOW. Connect the "bottom" of the switch to a 10K resistor. Connect the other end of that resistor to GND. Connect the junction of the switch and the resistor to pin 4.

#3. The LED will not be bright enough with a 10K resistor in series. Try a 1K instead.

[sccoupe]

Thanks Charles. Here is the correct schematic. The first one was misdrawn from what I wired. Does this correctly address #2? On issue #1, do I need two seperate sets of caps for the regulator and the pic or will one set do? Also are there small SMD caps available in those values? I've looked in the past and it seems that the 10uf caps are big metal button types or the non-smd electrolytics.


Thanks again for the info.

Jason

[sccoupe]

Will these do for the capacitor situation?

Cap 10uf

Cap .1uf


If these are not used at all, how does that effect a pic that is being used to count rpm pulses?

Thanks

[BobEdge]

Yes those caps will be fine, without them the circuit will be vunerable to electrical noise & may give unexpected results.

Also for the led resistor I would use around 270 ohms.

Regards
Bob...