I’m working on a controller for sequential stairs lighting. I’m sure You seen something like that, steps lighting up from first step to last then diming down and the same for going down the stairs.
I have the program part figured out and all elements (except LM7805) conected on breadboard but I need it to be more… durable.
So I’m using Arduino Nano; LM7805 to drop down the voltage from 12V to 5V to power the Arduino from LED power supply; TCL5940 to expand my PWM outputs, 16 of STP16NF06L to drive the LED strips (strip connected to +12V andit’s GND to the conector driven by transistor) and some minor elements (potentiometers, motion sensores, and simple elements).
I created diagram in Eagle, but I still have some questions and would like to someone with experience to look it over.
So I have following questions:
-I want to power the Nano with LM7805, drop by 7V is big, but after brief search this seems like the simplest/cheapest option. About securing the circuit I can see there is something simillar in : https://forum.arduino.cc/index.php?topic=604879.0, so I’ll keep my eye on it, but there is one thing. I’m going to use (on input and output) electrolytic capacitor 200uF and ceramic 100nF (saw it in some tutorial for powering Arduino). However Fesanand says he will use capacitors as the spreadsheet says, and my says 0.33uF on in and something more than 0.1 on out. Why then people are using something different? Is there a way (or rule) on choosing proper capacitance or just trials?
https://www.sparkfun.com/datasheets/Components/LM7805.pdf bottom of the 3rd page.
-I’m going to power arduino through +5V pin. Some people say it’s dangerous, because there is no regulator on it, but with protection on previous step it should be fine. Right?
-LED strips are going to be connected to +12V and theirs “-” to transistor to GND. Can and do I need to protect the circuit if someone provides +12V here? Like shortening the wires on LED strip?
-As per moving it from breadboard, like I said I tried Eagle free, but board allowed there is way to small. I can see on forum that there are alternatives to it, but still, Eagle said it’s about 300 connections and I have no idea where to start on placing elements. As the current/signal flows? Big elements with most connections first? Although I suppose there is no easy answer for that.
I’m aiming at prototyping board and making connections myself, but if design would require printing, I can get around that too.
Any other tips appreciated.