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916  Using Arduino / Project Guidance / Re: Snail-Mail box notifier on: August 25, 2012, 04:42:19 pm
Using the TX2 and RX2 you can use the ardunio at the receiver end, triggered by a VT from the HT12D,  or you could use an ardunio both ends with Virtualwire to send the data .
917  Using Arduino / Project Guidance / Re: Snail-Mail box notifier on: August 25, 2012, 04:19:05 pm
I think I saw you were in Denmark ?  you can get a TX2 and RX2 transmitter / receiver pair ( I use them for my scoreboards with 250m range )

Use a HT12E in the mailbox, with the TE pin being shorted to ground by the microswitch,   and  HT12D to decode , you can latch a LED  to  show  " youve got post " and you can connect a buzzer to the VT  ( valid transmission ) pin to sound an alarm.

Sorry Arduino, youre overkiil for this project :-)
918  Using Arduino / Project Guidance / Re: Snail-Mail box notifier on: August 25, 2012, 03:50:15 pm
You could use a pair of SIM20 transceivers ( you dont have to do anything to use one as a transmitter and one as a receiver if you want to keep it simple )

They reckon 1500m in free air, I have tested a pair over  150m  )( the length of my road ) and they were fine.

Hang a 170mm length of wire from the bottom of the mailbox as an antenna.

I don't know what trigger you will be using to detect a mail delivery, but it could bring the transmitter unit out of sleep, and send a code, and go back to sleep, so the battery should last a year or so?

I use Virtualwire for data transfer, and use the PTT output from the chip to power the transmitter ( it has plenty of warm up time bulit in )  so the only quiescent current is from the Arduino chip itself.

You could skip the Arduino ( scandal ) and use a HT12E chip, and just trigger the transmit enable pin , it will draw nanoamps in standby

919  Using Arduino / Project Guidance / Re: Controlling 70+ LEDs with UNO R3 on: August 25, 2012, 03:28:06 pm
You can use 9  TPIC6B595 driver latches, mounted on perf/vero board, with a resistor somewhere  in each led segment, and just 3 wires to the arduino, ( 4 wires if you want to dim the brightness )
I can post a schematic if you like
920  Community / Gigs and Collaborations / Re: Need basic programming and design help. WILLING TO PAY FOR EXPERT HELP on: August 25, 2012, 02:01:32 pm
I have just survived a " has to be working in 3 weeks project "  everyone told me it was impossible.

 OK it was a much bigger challenge than yours, but you know what ? 

Everyone was right, it took 5 weeks and a lot of blood pressure pills...
921  Community / Gigs and Collaborations / Re: Advice on very simple project for newbie please. on: August 25, 2012, 01:56:01 pm
@ Grumpy Mike and Awol,  well said.
922  Community / Gigs and Collaborations / Re: Fun and challenging product design project: Who will step up? on: August 25, 2012, 01:53:03 pm
I would like to help, I am in Cape Town, and while not a " programmer" , I can usally come up with simple lateral thinking solutions.

I already have a vague idea for simplifying the display.     PM me if I can help ( time is sometimes tight, I am also trying to help rhinos , and make a living :-)
923  Community / Gigs and Collaborations / Re: Need Basic Help w/ Project (Will Pay) on: August 25, 2012, 01:44:39 pm
In the old parts of the Empire, a switch ( sort of )  implies double throw, and a button momentary......
924  Community / Gigs and Collaborations / Re: Advice on very simple project for newbie please. on: August 25, 2012, 01:41:06 pm
Hi Scotty jnr

Try contacting Crossroads, his signature says he is available for design / manufacturer, and hes not a grumpy guy at all :-)
925  Using Arduino / Project Guidance / Re: newbie guidance with a simple project on: August 25, 2012, 01:37:09 pm
I think we are all curious about which day the LED must come on..   perhaps an " its my birthday badge for your kid/kids - various dates ?  "
926  Topics / Interactive Art / Re: Check out my new COOL project on: August 25, 2012, 01:27:59 pm
Hi ,
your candles look very cool, and I like the tapered cone at the top.

With respect, I think you might be losing out on one of Arduinos options,  the pwm outputs on say pins 9,10,and 11.

With just a little code, you can have the option of the colours gradually changing through ( nearly ) the whole spectrum of colours. *

You could have a remote button to start it changing, and another to  "freeze" the ramp, to match the restaurants colours for example...

You could also make the flicker a more gentle candle flicker by ramping it on and off.

*  I used to make an LED mood light with just 2 quad op amp chips that controlled up to 16  lamps, and it gradually changed colour with no "steps" that you get with the normal micro mood lights.  By connecting the various lamps differently you could get an infinate number of different colours gradually changing in different parts of the garden / restaurant
927  Using Arduino / Project Guidance / Re: Arduino MEGA current draw predicament on: August 25, 2012, 01:07:42 pm


I would use 6 TPIC6B595 latch/drivers...
I was looking at those, but there were two problems I thought I may have with them.
First of all, I can't seem to find any decent tutorials for these 595s. They are fairly new to me and I would have to figure out how to convert a numerical value to a specific pattern of I/O to drive each of the relays. I also already have the code figured out for my original idea that didn't require these 595s.
Another issue I just thought of was that I'm using a ChronoDot for the time keeping, and it uses those same clock and latch pins that these 595s would otherwise seem to use and I'm not sure if they would like to share with the ChronoDot.

The TPIC6B595 is the same as a 595 serial register, but has a built in LED/relay driver ( like a ULN2003 )

You can use any 3 pins to drive them, using Shiftout,  and to set up the segment pattern I define a lookup table ( before the setup ) which looks like this for the pin connections I use from the TPIC to the segment :-

#define latchPin 11  // rck  the pin you choose to go to the latch input of the TPIC
#define clockPin 10  // sck   the pin you choose to go to the clock input of the TPIC
#define dataPin 13  // ser in   the pin you choose to go to the serial  input of the TPIC

const byte digitTable [10] = { // the patterns of segments for numbers 0 to 9 
 B11101110, B00101000, B10110110, B10111100, B01111000, 
 B11011100, B11011110, B10101000, B11111110, B11111100};

// and then at the end of the sketch when you want to display the data you just send something like :-

 digitalWrite(latchPin, LOW); 
 delay ( 50 );

  shiftOut(dataPin, clockPin, MSBFIRST, digitTable [ mintens ] );  // you can also have seconds if you like,
  shiftOut(dataPin, clockPin, MSBFIRST, digitTable [ minunits ] );
  shiftOut(dataPin, clockPin, MSBFIRST, digitTable [ hourtens ] );
 shiftOut(dataPin, clockPin, MSBFIRST, digitTable [ hourunits ] );

 digitalWrite(latchPin, HIGH);
  delay ( 50 );

The TPIC has a latch, so you dont have to refresh the display ( and you can take a video of the display without the scrolling bands moving down )
928  Using Arduino / Project Guidance / Re: Countdown Clock on: August 23, 2012, 02:35:44 am
Welcome to Arduino.

Do a search ( within arduinos search engine top right )  on "countdown days" or " days left " and so on, I am sure I have seen similar projects.
And have a look at the " time" library, I think there is a function to give the days. ( or seconds ) from y2k ( remember that abreviation ?, and all the fears it bought :-)

Try putting a sketch together, and post it (   select your actual code part of the sketch and click on the hash ( insrt code ) symbol above the text panel , this will keep the posting  shorter )  and there are thousands of guys who can help, and dont worry about silly mistakes, nobody will laugh, we all did it !
929  Using Arduino / Project Guidance / Re: Arduino MEGA current draw predicament on: August 23, 2012, 02:22:21 am
I would use 6   TPIC6B595  latch/drivers, you only need 3 pins of the Arduino , and it will give you 48 high power 500mA sink outputs to switch your relays ( it has the 50 volt voltage clamp diodes built in )
The relays will give you the isolation you  need.

I use this arangement for LED displays with up to 20    7 seg numbers.
930  Using Arduino / Project Guidance / Re: Pyro Firing system... Looking for a starting point on: August 22, 2012, 01:46:30 pm
I think you have strict controls for pyro systems over there, but have a look at the SIM20 wireless transceivers, you can build up a whole mesh of them with a mile range.
I have just started playing with them, and have just  got the basic  transmit/receive link working.
The datasheets are terrible, but the RFD21733 is similar, with less range but better technical backup.
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