I'm going to create a Word Clock after being inspired by the Biegert and Funk Qlocktwo, so after some googling I have found some guides on how to do it. But the problem is that most of them is made by creating their own arduino board and I decided to not do that but instead buy a Arduino Uno. So now I need help to check if I have understood the original schematics correctly when I redid it for a real Arduino. I can also add that this is my first ever project using an Arduino.
Also concerning the LEDs I'm not quite sure which resistors to use, so if anyone could tell me which ones to use/calculate which ones to use it would be much appreciated. I think I will power everything with either 9v/12v not sure which one would be most suitable for this project.
The LEDs are
Forward Voltage: 3.2-3.4V
Current: Not sure since the package didn't say anything. But my guess would be 20mA
As far as I have understood I calculate the resistor value like this:
(Power Supply Voltage - LED Voltage)/LED Current
But I'm not sure how to calculate if there is more than 1 LED.
They will be connected like this:
I would assume that it wouldn't change considering they are connected parallel. As I said previously it would be much appreciated if someone could tell me if this is correct or wrong.
Click Reply, then Additional Options, Browse to your diagrams/whatever and Attach them.
I can't get to gyazo.com.
Your formula for LED current limit resistor is correct. If you have them wired in series, then:
(Power Supply Voltage - LED Voltage - LED Voltage -LED Voltage -)/LED Current
for 3 in series from a 12V supply. You will also have a transistor at the bottom of the string, you could subtract another 0.7V for say an NPN transistors Vce, or (Rds x LED current) for a Logic level P-channel MOSFET.
Otherwise, your original formula for each LED in parallel - each needs its own resistor too.
TPIC6B595 is a good shift register for controlling strings of LEDs. Output is rated to 50V, can continuously sink 150mA per output channel. I use up to 12 of them on this board for controlling 7-segment displays: http://www.crossroadsfencing.com/BobuinoRev17/
You can see the Arduino functionality at the lower left, Serial programming is done via an off-board USB/Serial adapter.
Some use pin 10 Q'S for output to next D.
Others use pin 9 QS for output to next D.
I have used pin 10 in the past, but I noticed that you use pin 9.
What is the difference ?
According to the datasheet: "Two serial outputs are available for cascading a number of CD4094BMS devices. Data is available at the QS serial output terminal on positive clock edges to allow for high-speed operation in cascaded systems in which the clock rise time is fast. The same serial information, available at the Q’S terminal on the next negative clock edge, provides a means for cascading CD4094BMS devices when the clock rise time is slow."
But I still don't understand what is better.