Hi,
I am really new to all of this and I would love some help.
I am trying to build a 14x14 matrix of lightbulbs. (220ohm resistors would work)
I thought to use 4 shift registers SN74HC595 that control 28 darlington ULN2803A.
I have some questions about this:
Would this setup be good or is there any better solution?
I am trying to find some code to start experimenting with this setup.
I managed to use the shift register example on the arduino.cc and it works but I can't manage to control the darlington with the register.
lightbulbs matrix shift registers and darlington...
... (220ohm resistors would work)
You mean LEDs, right? 220 Ohm resistors are for "standard" LEDs, not light bulbs or high-power LEDs.
I thought to use 4 shift registers SN74HC595 that control 28 darlington ULN2803A.
I have some questions about this:
Would this setup be good or is there any better solution?
I am trying to find some code to start experimenting with this setup.
That sounds fine. Note that the ULN2803 is an inverting device. A high on the input "pulls down" the output, turning-on the LED.
Power -> Resistor -> LED -> ULN2803 -> Ground.
I managed to use the shift register example on the arduino.cc and it works but I can't manage to control the Darlington with the register.
You can test the ULN2003 and LED part of the circuit by applying 5V to an input. That should turn-on the LED. (Do this without the shift register connected.)
DVDdoug:
You mean LEDs, right? 220 Ohm resistors are for "standard" LEDs, not light bulbs or high-power LEDs.
I meant microbulbs. What I really need tu use would be resistors as I have to produce heat.
a small amount of heat. And I also need to understand how much, to be honest.
That sounds fine. Note that the ULN2803 is an inverting device. A high on the input "pulls down" the output, turning-on the LED.
That's a good hint. I will have a look into it. Today I did some experiment but There was some weird behaviour.
Power -> Resistor -> LED -> ULN2803 -> Ground.
You can test the ULN2003 and LED part of the circuit by applying 5V to an input. That should turn-on the LED. (Do this without the shift register connected.)
TomGeorge:
Hi, are you trying to make a programmable array or display that is only IR visible.
Or are you making a variable output heater?
I think we need some application info now?
Tom.....
Hi Tom, sure I can give more info.
I am not sure what is the difference between your two options, however I think both could be cool projects!
I am trying to create a sort of programmable matrix of resistors controlled by a camera input ( I have a lot of questions about that issue as well which I posted on another section, btw).
So ideally it would work exactly like a LED matrix that receives inputs from a camera (brightness threshold signal i.e., black an white on and off) This will react with a thermochromic surface. This is the project.
You will need a much lower resistor and hence much more current to see any effect.
Try it with just one resistor first.
Also it would be good to use surface mount resistors to get the "pixel" size down.
As it is thermal then your refresh rate only needs to be very slow to get the effect you are looking for.
I recall some one was asking about a project like this a couple of years ago.
