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661  Using Arduino / General Electronics / Re: History of the 555! on: February 10, 2014, 09:25:12 pm
The opamp might be useful but the 555 is so much more versitile....
662  Using Arduino / General Electronics / History of the 555! on: February 10, 2014, 12:23:03 pm
http://semiconductormuseum.com/Transistors/LectureHall/Camenzind/Camenzind_Index.htm

Thought I'd share.....
663  Community / Exhibition / Gallery / Just to share... (5 x 10watt RGBs) no current regulation! on: February 10, 2014, 10:31:31 am


Using just 2n2222s and a 68ohm resistor on each of the base pin, it pulls just under 2 amps when cold.... and sadly even when warm, it still pulls around 2amps!  - i've only had it running for about an hour tops so hopefully it gets brighter as it gets hotter lol (68ohm resistors to the base, and no current limiting resistor either on the emitter or collector, they are all sinked via an NPN)

This was simply a test to see what happens if you supply rougly 120ma to each RGB segment of the LED and when it got hot, would it rise to say 200 or even 300ma?... sadly not and if did, it has 200ma of leeway.

either way, it's damn bright for 20watts and hopefully Mr Grumpy is right about high powered LEDs increasing in current when hot because it'll only get brighter and stay well within the 800ma spec limit of the 2n2222's .
664  Community / Exhibition / Gallery / Re: Simple Colour Change Lamp on: February 10, 2014, 10:24:44 am
I figured it's kinda pointless seeing it in daylight... so I just switched it on (it's 1am, plenty dark enough i suspect)



oh and just to explain... I'm using 2n2222's  smiley-grin   and no "current regulation"  each npn can deliver around 800ma, so I use a 68 ohm resistor to the base pin for each segment, this rougly supplies 120ma per color which is well within spec of the transistor... I purposely kept it low knowing that when the LED heats up, i expected the current to rise up to 200 maybe 300ma, in which case it's well within spec of the 800ma limit of the transistor AND within the 300ma per RGB channels from the 10 watt.

So, 120ma * 3 * 5 =  1.8amps or 21watts.

The multimeter reads 1.8 - 1.9 amps...

Now, because I have no current limiting resistor on the emitter/collector side of the LED, it relies just on the 68ohm resistor, I originally was going to use something like a 30-40ohm resistor and 1/4watt was not up to the job, so i stuck with the 68 ohm resistor and *hoped* that once the LED's warmed up, it would draw more current to get to the 300ma mark.

And (as I suspected) ... No.

The heatsink keeps the LED's cool and sadly (even in 45c / 100f+) heat, still no... maybe if i run it for a few hours instead of 30 - 40 minutes the current will slowly creep up? - good because I like bright.

next time i'll use 1/2watt resistors and push the 50watt boundy, as it is 21watts is bright enough.

665  Community / Exhibition / Gallery / Re: Simple Colour Change Lamp on: February 10, 2014, 09:47:31 am
Over the weekend, I finally got around to finishing a similar thing, except i used 5 of them... potentially it can supply over 50 watts of light but I decided to limit the current, it pulls around 2amps at 12v (or 24watts) and decided that's bright enough.



But i also did what you did using an attiny85 for the bedroom, they certainly beat 5mm LED mood lights you get from shops..
666  Community / Bar Sport / Re: A broken Arduino... on: February 10, 2014, 08:56:15 am
Probably not worth doing... but you could replace the voltage regulator and possibly one of the ceramic smd caps and bring it back to life...

i'm amazed it works at all, i've killed 2 clones after supplying just 12v! (with no load either)
667  Using Arduino / Project Guidance / Re: Forty-two Unos in a row on: February 10, 2014, 05:47:41 am
The nrf radio module might be an option, each one could listen and broadcast to everyone else, it should save you on running a lot of cable, and I guess more options when it comes to controlling them.

http://www.ebay.com.au/itm/2-PCS-NRF24L01-2-4GHz-RF-Wireless-Transceiver-Module-for-Arduino-/230791084009?pt=AU_B_I_Electrical_Test_Equipment&hash=item35bc3877e9&_uhb=1


Bulk buy, you should get them to around a dollar a module.
668  Using Arduino / Project Guidance / Re: Can I power my Arduino with a MintyBoost? on: February 10, 2014, 03:59:44 am
I doubt any harm will come... but it could do with some filtering to smooth out any voltage fluctuations.

669  Using Arduino / LEDs and Multiplexing / Re: Is it possible to control thousands of leds with arduino? on: February 08, 2014, 11:17:51 pm
Unless you design a pcb and use the tracks, prototyping one that uses just 100 leds would be a pain in the arse.

Take a look at addressable leds (which have the shift register embedded in the led)
670  Using Arduino / Project Guidance / Re: Controlling devices connected to arduino uno+bluetooth through android. on: February 08, 2014, 05:19:36 pm
Well yes, once you establish a connection to your arduino via a bt module,  you use uart via a hard/soft serial port, then it's a case of parsing the data..

Simplicity send 'A' from android

GetData .. serial.read. .
If (byte=='A')
  digitalWrite (pin, HIGH);

Etc
671  Community / Bar Sport / Re: Where to go to start developing apps? on: February 08, 2014, 07:05:06 am
Apple was first at what?...

I never said anything about being first!
672  Using Arduino / Project Guidance / Re: Controlling devices connected to arduino uno+bluetooth through android. on: February 08, 2014, 06:23:15 am
Bluetooth on android works via an intent, it's not newbie friendly. .

http://developer.android.com/guide/topics/connectivity/bluetooth.html

673  Using Arduino / Project Guidance / Re: How to read a square wave using arduino on: February 08, 2014, 06:16:14 am
By feeding it into an analog pin, then measuring the value you get...

Providing the 555 gives a voltage out less than 5v or use a voltage divider.
674  Using Arduino / Programming Questions / Re: Want Relay with Button and Time Limit, not sure if loop will work correctly... on: February 08, 2014, 05:53:08 am
The delay freezes the program.

The none delay works like someone using a stop watch, so you get the millisecond count and at some point you get it  again, you compare the two time stamps (oldtime-newtime) gives how long it's been running for, be 5 seconds or 5 hours.

But where's the code?
675  Community / Bar Sport / Re: A broken Arduino... on: February 08, 2014, 05:47:59 am
A badArduino?

Ooo a badassArduino (uno rev 6? )
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