Hello,
I want to make an stairway lightning with RGB Ledstrip.
I have 12 steps, I want to use 1 strip for every step.
It is an 24V Liniled from Osram. 1 piece is 80cm, and uses 166mA max.
I want to control evey strip seperate, and even control the brightness with an Arduino Uno.
When i have 12 steps and with each 3 colors, i think i need 36 outputs
The Arduino doesn't have that much outputs.
I was thinking of using some shiftregisters 74HC595 in combination with an ULN2003
My question is: Is this possible?
And have somebody some information about this?
Yes, 74HC595 shift registers + ULN2803A + ShiftPWM software would be a good solution. With all that power being switched, you are going to need a very good ground connection between the chips, and good decoupling.
You could use something like these RGB LEDs from adafruit. They're linked with a serial bus so you only need two pins on the arduino to control as many as you need.
You could use something like these RGB LEDs from adafruit. They're linked with a serial bus so you only need two pins on the arduino to control as many as you need.
I don't know if this works for me, this are digital leds with an adress. The ledstrip i use is an analog strip, it is not possible to control each led.
Yes, 74HC595 shift registers + ULN2803A + ShiftPWM software would be a good solution. With all that power being switched, you are going to need a very good ground connection between the chips, and good decoupling.
I have made a schematic of this. i send it as an attachment.
I don't have an ULN2803A but instead i want to use an ULN2003, it is almost the same.
And this al in combination with ShiftPWM. i have made an example for 4 RGB strips, but i want to extend it for 12 RGB strips.
Is The schematic alright in your opinion?
Or do i have to do more.
Add a decoupling capacitor between pins 8 and 16 of each 74HC595, as close to the 74HC595 as possible. 0.1uF ceramic will do. Also a decoupling capacitor between the +24v supply to each LCD strip (or pair of strips) and pin 8 of the ULN2003 driving it/them. For this decoupling capacitor I suggest 0.1uF ceramic in parallel with 10uF or greater electrolytic. Otherwise it looks OK to me, provided that the LED strips already contain series resistors so that they can be connected direct to 24v.
Yes, that's right. Make sure the capacitors are located close to the respective ICs and the leads to them are as short as reasonably possible (you can't really show that on a schematic).
