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31  Using Arduino / Project Guidance / Re: 20-30 digital buttons on one board on: September 08, 2014, 09:22:23 pm
Have a look at the 74HC4067, a 16 channel multiplexer/demultiplexer. You'll need 6 pins on your Arduino (and a transistor) to drive 2 of them, giving you 32 inputs.

4 pins for the address
1 pin for chip select (using the transistor to invert to one enable pin & non-invert to the other enable pin.)
1 pin for input
32  Using Arduino / Programming Questions / Re: LT1867 ADC - What pin is the unit8_t cs pin actually referring too ? on: September 07, 2014, 08:04:43 pm
Code:
 int looped;
  looped = looped++;
What value is in looped when the first statement is executed? If you said 0, you are wrong. If you said "some random garbage", you are correct. Now, why would you want to increment some random garbage?
And looped will never exceed one more than its initial random value, as it's being reinitialised every time around loop().
33  Community / Bar Sport / Re: couldnt find a computing section to the forum but anyway on: September 06, 2014, 09:55:09 pm
...and if you want to see an earlier form of a "moving head disk drive" - a really great one is the Bryant Model 2 Disc Files from 1965:

http://www.computerhistory.org/collections/catalog/102646212
A computer lab technician friend of mine has a 30" dia. by 1/2" thick steel disk from a similar drive in his office. I'd hate to have been around one of those if the bolts holding it in place sheared...
34  Community / Bar Sport / Re: quantum crypto device on: September 06, 2014, 09:46:01 pm
The security services won't like that.
They won't be able to read your emails!  smiley-wink
35  Using Arduino / General Electronics / Re: PCB copper clad Stencils? on: September 06, 2014, 09:37:31 pm
I've been looking all over but they may not even exist...

What I thought would be pretty cool, a plastic stencil with IC cut outs of various sizes, dip, sop, sip, smd etc etc...  all you would do is place the stencil on top of the copper clad using a marker suitable, simply fill in the gap leaving a solder pad footprint on pcb all one does then is draw in the tracks and finish it off.
Not quite what you're suggesting, but you could use rub-down etch resistant transfers.
http://www.jprelec.co.uk/store.asp/c=686/Etch-Resist-PCB-Transfers
36  Using Arduino / Project Guidance / Re: Coding multiple led high low quickly on: September 06, 2014, 08:35:34 pm
What is ATM

Post your code
Probably ATM = At The Moment.
37  Community / Bar Sport / Re: Arduino Community Logo on: September 01, 2014, 10:36:36 pm
What would be really cool would be a logo rendered as one of those Magic Eyes 3D pictures, so that if you squint and stare at it long enough, it reads "Post your code" in 3D letters.
It also needs to be in 76pt dayglow coloured font.
38  Using Arduino / General Electronics / Re: hobby servo motors on: September 01, 2014, 10:30:33 pm
Hi All,
                Well I've taken AWOL's advice and tried a meter, with a few jumper cables, I put my DMM in line with the supply and got!!
245mA when the servo was actually moving, 800mA plus if stalled, and about 42mA when it was holding steady. I still think this current is just there to hold the postion, and so yes it still needs to be powered, if it is to hold postion and not move under the force of the load, whatever that may be.

Regards

Mel.
What current does it take when you try to manually move it? I suspect it will be much more than 42mA.
39  Using Arduino / General Electronics / Re: Control 24V relay using Arduino Mega (5V available and other side 24v required) on: September 01, 2014, 10:17:51 pm
I am new for Arduino but I am good at programming so I can turn on/Off pins using other conditions and sensors value but at other side I need 24 V to operate.

What are the possible options  for turn on and off 24V source which goes to relay?
I heard about PNP transistors but I am not sure that it will damage Arduino pins ?
And if I can than which Transistor should I use ??

And if following solution is good then can anyone explain me ?
http://kellykeeton.com/wp-content/uploads/2013/08/drive-relay.jpg
Yes, that's the correct way. What relay are you using?
40  Using Arduino / Programming Questions / Re: Day-of-Year conversion to Date, how??? on: September 01, 2014, 09:59:04 pm

  return Month, dayOfMonth;

this is valid C but does not do what you expect. IN C you can only return 1 value.

with respect to time:

ticks = 1387;                  // example
hr = ticks/60;              // 60 minutes in an hour 1387/60 = 23  (truncated integer math )
mi = ticks - hr*60;     // 1387 - 1380 = 7
Or mi = ticks%60;
41  Using Arduino / Project Guidance / Re: Arduino shield compatibility on: September 01, 2014, 09:15:32 pm
iam not 100 percent sure but i think you may attach all of them together like

-----  xxxxx
-----  sensor
-----  ethernet
-----  arduino uno

can i go with mega or arduino uno ?
You could go with either, as shields are usually compatible with both.
But before you do that you should check that there are no pin conflicts (more than one shield trying to use the same pin for different functions doesn't work!)
42  Using Arduino / Project Guidance / Re: Robot arm for PCB etching on: September 01, 2014, 08:34:32 pm
Im not ture if you will understand this but ill have a go.

Imagine a pair of wheels  mounted vertically above another pair, connected by something , a bit like a bycicle chain.
Pcb mounted on hangars , with hooks attatched to the rope.
As pulley rotates hooks engage on hangars which are lifted clear then moved sideways as it travels around the top pulley before descending to next tank.

Times two gives 3 tanks , times four gives feed and removal option.

Iv seen this arrangement but have no idea what its called
I think you've the right idea with the chain, but I would use two (one either end of the tank)  and hang the PCB horizontally between them. The chains can be made to follow the path the PCB will take, using free running rollers to raise or lower the chain in the correct places. The PCB can sit in a dense (so it doesn't float) plastic tray with some holes in, suspended from the chain on something like cable ties or thin plastic cord. If the width of each tank is set correctly, there would be no need to adjust the speed or stop the chains when the PCB is in each tank. The mechanism can be extended beyond the last tank so that the completed PCB is tipped off the tray to land safely on a piece of foam plastic.
43  Using Arduino / Programming Questions / Re: LT1867 ADC - What pin is the unit8_t cs pin actually referring too ? on: August 30, 2014, 10:02:32 pm
It's uint8_t (unsigned 8 bit integer), not unit8_t.
I've found it makes things much easier to find if you're looking for the correct thing.  smiley
44  Using Arduino / General Electronics / Re: "Group purchase" of electronic components on: August 28, 2014, 11:21:28 pm
Also note that many of the members of this forum do not live in the USA.
45  Using Arduino / General Electronics / Re: Okay to mount Arduino to Styrene? on: August 27, 2014, 10:19:28 pm
I've used 1.5mm styrene sheet to mount my Arduinos inside a metal case without any problems. As long as you've nothing rubbing the styrene, like a wheel or motor part, I think you'd have no problem. How else would you get static build-up?
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