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[on:]

Hi,

I need to get this project done as soon as possible (it's part of a bigger project for university), so any help is much much appreciated! Everything works with 1 LED as well as 8 LEDs (on a breadboard using 330 ohm resistors), however I would like to use the LED cluster I bought instead of just 1 LED or 8 LEDs. Also, if you have an ideas for increasing the sensitivity of a sound sensor, please let me know

I have the following LED Cluster from Maplin: http://images.maplin.co.uk/300/pd01b.jpg
How would I go about connecting this LED cluster to the Arduino? (Please bear in mind I am a total newbie in electronics).

Code:

int sensorPin = 4;
// Setting the input pin for the sound sensor
int ledPin = 13;
// Setting the output pin for the light emitting diode
int val = 2;
// Variable to store the value coming from the sensor

void setup() {
pinMode(ledPin, OUTPUT);
// Setting ledPin as the output
Serial.begin(9600);
// Initialising serial communication with computer
}

void loop(){
val = analogRead(sensorPin);
// Reading the analogue value from the sensor
Serial.println(val);
// Sending the signal to the computer in the form of ASCII digits

if (val > 3) {
// If the signal value received from the sensor is higher than 460
digitalWrite(ledPin, HIGH);
// Then turn the LED on
}
else {
// Otherwise
digitalWrite(ledPin, LOW);
// Turn the LED off
}
delay(30);
}

LED Cluster details:

Specifications (IF=200mA)                                 
Maximum luminous intensity:   23000mcd                              
Viewing angle:   40°                              
Typical forward voltage:   9.6V (11.2V)                              
Peak wavelength:   660nm                              
Maximum reverse current:   100µA @ VR=18V                              
Power dissipation:   2.5W max.                              
DC forward current:   250mA max.                              
Reverse voltage:   5V max.                              
Operating temperature range:   -5°C to +65°C


As I said before, this is for uni, so I am stressing a lot right now, any help is appreciated

[Reply #1 on:]

There's more than one way to go about this.
The attachment is but one of many.
(It features a "logic-level" MOSFET.)

[Reply #2 on:]

Hi thanks for your reply. My problem is also I don't really understand most technical schematics :/ The only thing I recognise are the resistors 
I have a 9v battery box the cluster can run off by itself (if attached directly). Would I be able to use this as power for the Arduino, that will then power the LEDs?

[Reply #3 on:]

Hi thanks for your reply. My problem is also I don't really understand most technical schematics :/ The only thing I recognise are the resistors 
The LED cluster is represented by the diode inside the big circle, you get the resistors, so all what's left is the MOSFET.  You can do a little "googling" on that much, mate.

I have a 9v battery box the cluster can run off by itself (if attached directly). Would I be able to use this as power for the Arduino, that will then power the LEDs?
9V is not enough.  The name of the game for the LED circuit is: "12V Or Bust".  The Arduino should be OK with 12V as "V_in".

[Reply #4 on:]

Is there any way of doing the same with one of the products Maplin offers? (They're open on Sundays, so I can go and buy it tomorrow.)
http://www.maplin.co.uk/search?criteria=MOSFET+op-amp

[Reply #5 on:]

Why search for op amps?
You want a logic level FET and a 12 V supply, a 9V battery pack is not sufficient.

[Reply #6 on:]

Maplin doesn't have a lot in the way of MOSFETS, two actually.
They have an IRF540, but it will require an NPN in front of it, to switch the gate voltage (5V not enough.)

http://arduino.cc/forum/index.php?action=dlattach;topic=101169.0;attach=16753;image

In that schematic, the LED cluster and those 33Ω resistors is/are the block labelled "Load".
It's "On" when the Arduino output is LOW and it's "Off" when the Arduino output is HIGH.

* * * I know that there are NPNs good with getting > 200mA and more stuffed down them, but I was thinking how 1 cluster turns into 2, turns into 4...  
Anyway, I don't know what's "ideal", but this'll get the job done.  It's not beta-dependent and V_ce isn't an issue either. * * *

[Reply #7 on:]

I only need that one cluster and I want to use the simplest way possible. Would that be by using the Logic Level Mosfet you described in the first post?
I have ordered one off eBay, hope it arrives soon...

[Reply #8 on:]

Well you could get the NPN transistor and the FET from Maplins today, it will do the same job as the logic level FET.

[Reply #9 on:]

Thanks for helping everyone. Just to make sure are these all the things I need?

http://www.maplin.co.uk/480-piece-e3-resistor-starter-pack-42453
for one 4K7ohm resistor.

http://www.maplin.co.uk/mos-fet-transistors-33843
one IRF540A MOS-FET transistor.

http://www.maplin.co.uk/33andohm-to-91andohmmetal-film-0.6w-resistors-341561
three 33ohm resistors

As I said, I am a total newbie in electronics, still kind of clueless (see illustration of my cluelessness below)  

[Reply #10 on:]

I would go for a 10 ohm 10 Watt resistor in place of the three 33R resistors the catalog number is H22R

[Reply #11 on:]

Hi thanks, I have now reserved these items:

H22R - 10W W/W 22R1
N63BH - E3 Resistor Pack1 (for the 4K7 ohm resistor)
N10AH - IRF540A

Is there anything else I need? Could someone please have a look at the image I posted, I don't understand it completely. What's 2k? Another resistor? And why are there two 12v inputs?
Again, thank you so much for helping out 

[Reply #12 on:]

What's 2k? Another resistor?

Yes but you could use the 4K7 to save you getting another value.

And why are there two 12v inputs?

Just connect them to the same place.

You might want some strip board to build it on.

[Reply #13 on:]

I would go for a 10 ohm 10 Watt resistor in place of the three 33R resistors the catalog number is H22R

The big, fat leads of those guys are hard to cram into breadboards.

cschmeer,
Are you an adept solderer?

[Reply #14 on:]

I made you a pictorial - I'm in an unusually good mood this morning.
I'm an atavism, an unapologetic fossil, a techno-coelacanth who puts pen to paper and uploads a picture of same.  (I don't/won't do the "fritzing" thing).

That cluster/module has a red lead and a white lead, but I didn't see anything in their info as to which is which, so I'm going with the "red=positive" assumption.  You may want to get some guidance from the good people at Maplin (who are anxiously awaiting your call.) 

[I have some similar devices which have red & green LEDs. Their lead out is White (CA), Red (reds K), Green (greens K).]