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121  Using Arduino / General Electronics / Re: vacuume mosfets :) on: July 06, 2014, 10:08:56 pm
http://spectrum.ieee.org/semiconductors/devices/introducing-the-vacuum-transistor-a-device-made-of-nothing

To Vacuume or Not to Vacuume.

First came crystals to aid in rectification.
Then came vaccume tubes
War showed valves to be slow and were replaced by solid state.

Now in 2014

Vacuume x Mosfet = transistor to operate in the THz range :o


(Edit is it Vacuum or Vaccume? )
It's not a vacuum, as it's filled with Helium at 1 Atm (14 PSI). But will we have to keep them in upturned boxes or scrape them off the ceiling.  smiley
122  Using Arduino / Programming Questions / Re: Code optimization: state machine for different duration events on: July 06, 2014, 09:29:22 pm
Instead of this:
Code:
// Configure digital pins 2 to 5 to control relays that control the solenoids.
   arduino.pinMode(solenoidData[0][0], OUTPUT);
   arduino.pinMode(solenoidData[0][1], OUTPUT);
   arduino.pinMode(solenoidData[0][2], OUTPUT);
   arduino.pinMode(solenoidData[0][3], OUTPUT); 
try this:
Code:
for(int x=0; x<=3; x++){
 arduino.pinMode(solenoidData[0][x], OUTPUT);
}
123  Using Arduino / Programming Questions / Re: If statement takes 1kb of memory on: July 06, 2014, 09:02:15 pm
A minor saving: Changing
Code:
int reading = analogRead(sensorPin);
  int sensorValue = 100-(reading-minimum)/(maximum-minimum)*100;
to
Code:
int sensorValue = 100-(analogRead(sensorPin)-minimum)/(maximum-minimum)*100;
saves the space of an int., as you don't appear to be using 'reading' elsewhere in your code.
124  Using Arduino / Programming Questions / Re: Could you tell me waht is the problem with this code! Thank you:D on: July 06, 2014, 08:27:23 pm
Code:
b = a;
change to
Code:
b=a[i];
He appears to have put in the
Code:
[i]
but, because he didn't use code tags, it has turned everything following into italics. That's why [code ][/code ] tags are essential.
125  Using Arduino / Programming Questions / Re: Read rpm's of a Motor by interrupts on: July 06, 2014, 08:08:02 pm
Hi,
I have to read the rpm's of a motor that can run between 1000-2000 rpm, using, an inductive sensor.  I'll use interrupts to read the rpm's of the motor with an Arduino Mega, but I don't know if will be able to detect all the interrupts (1000-2000 rpm = 1000 - 2000 interrupts /min = 17 -34 interrupts / second).
Why use interrupts? Your pulses will be about 30 milliseconds or more apart. Look up the pulseIn construct.
126  Using Arduino / Project Guidance / Re: Can an Arduino be powered by a Rochelle Salt Crystal? on: July 06, 2014, 07:54:43 pm
I can't help but think, everytime I pass by this topic, that Dilithium crystals would be better.
Forget Dilithium, Kryptonite is much more powerful...and it's a pretty green colour.
127  Using Arduino / Project Guidance / Re: big keypad on: July 06, 2014, 07:38:05 pm
Thinking about a keypad - a Big Keypad! 16 x 16.
You're unlikely to lose that down the back of the sofa!  smiley
128  Using Arduino / Project Guidance / Re: Button and pushwheel on: July 05, 2014, 09:09:34 pm
Well I have two types of pushwheels, one with 10 outputs and 1 common, the other with 4 outputs and a common. But I am using the first one (10 outputs).  I am also putting this with a LCD . This is what I was able to get, only with the pushwheel. I did this code earlier today before I posted on here.
Put a push to break switch in the common line of your pushwheel. Push it whilst turning the pushwheel and release it when it's set correctly. Try:
Code:
const int led1 = 4;
const int led2 = 5;
const int led3 = 6;
const int led4 = 7;
const int sw1 = 13;
const int sw2 = 12;
const int sw3 = 11;
const int sw4 = 10;
const int lcd = 1;
int val1 = 0; //You don't need these
int val2 = 0; //You don't need these
int val3 = 0; //You don't need these
int val4 = 0; //You don't need these
int input = 0;

void setup(){
  Serial.begin(9600);
  pinMode(lcd,OUTPUT);
  Serial.write(12);
  Serial.write(131);
  Serial.write("The Bartender");
  pinMode(led1,OUTPUT);
  pinMode(led2,OUTPUT);
  pinMode(led3,OUTPUT);
  pinMode(led4,OUTPUT);
  pinMode(sw1,INPUT);
  pinMode(sw2,INPUT);
  pinMode(sw3,INPUT);
  pinMode(sw4,INPUT);
  Serial.write(192);
  Serial.write("Pouring in:");
}
void loop(){
   input = digitalRead(sw1) +(2*digitalRead(sw2)) + (3*digitalRead(sw3)) +(4*digitalRead(sw4));
  //input will hold 0, 1, 2, 3 or 4 (assuming that no two inputs can be on at any one time)
   switch (input){
     case 0:  digitalWrite(led1,LOW); // all off
              digitalWrite(led2,LOW);
              digitalWrite(led3,LOW);
              digitalWrite(led4,LOW);
              //Clear your screen here.
              break;
     case 1:  digitalWrite(led1,HIGH);
              digitalWrite(led2,LOW);
              digitalWrite(led3,LOW);
              digitalWrite(led4,LOW);
              Serial.write(168);
              Serial.write("Opt 1")
              break;
     case 2:  digitalWrite(led1,LOW);
              digitalWrite(led2,HIGH);
              digitalWrite(led3,LOW);
              digitalWrite(led4,LOW);
              Serial.write(173);
              Serial.write("Opt 2")
              break;
   //etc., etc.
.
     default: //you only get here if there's been an error.
                   //You may want to output a warning to your screen here
             input = 0; //switch everything off.
             break;
    }
}
129  Using Arduino / Project Guidance / Re: KVM over IP with arduino? on: July 05, 2014, 07:59:26 pm
hmm... ok thas a posibility, but there are a few problems
1. USB 2 VGA adapters work only after the BIOS initialised the driver, so no bios level access.
So how does my USB keyboard (and USB mouse, on my 64bit machine) allow me to access BIOS?
130  Using Arduino / Project Guidance / Re: Help with mountain biking race (enduro) timing system on: July 05, 2014, 07:39:54 pm
Hmmm interesting. I never thought about using a repeater at the highest point. I'm not sure about distances as the crow flies but on the trail you're talking anywhere from 0.5 to 3 miles max (much shorter as the crow flies). I thought about a fixed cable but that would be a nightmare trying to carry around a massive amount of cable (weight considerations) and not to mention it would take a long time to roll that away and deploy each time.
That's why I used the term 'fixed' cable. Have your cable fixed to poles or trees and leave it there. For each 'meet' you'll need a ladder so you can connect a drop wire at each end.
Quote
As for collection of data, I haven't determined that yet. The simplest way would be to just manually read each start station at the end of the race (they would be collected along the way) and tabulate the data.
How 'manually'? You can't open up a microcontroller and see all the zeros and ones.
You call it a race. Is there going to be more than one rider on any one section of the course at any one time? Or is it a time trial with each rider completing each section on their own, against the clock? If so, I'm sure the riders would want to know how they are doing after each stage and the time to beat in the next stage.
131  Using Arduino / Project Guidance / Re: Can an Arduino be powered by a Rochelle Salt Crystal? on: July 05, 2014, 06:49:21 pm
Quote
tapping on a crystal to get an electrical output is a not so distant cousin of such creation.
Is totally and utterly wrong.
Agreed. Has nobody told him that "energy can neither be created nor destroyed."? Physics 101, lesson 1.
132  Using Arduino / Project Guidance / Re: Could you... on: July 05, 2014, 06:28:07 pm
could you use an arduino and something like this

http://www.ebay.co.uk/itm/Micro-SD-Card-extension-cable-/121378426009?pt=UK_Photography_MemoryCardReaders_RL&hash=item1c42b7cc99

to fool a device that the memory card always had room??

so you would plug the micro sd card/cable into a device, which is connected to an arduino, the arduino is either plugged into a computer or directly into a hard drive and the device would just keep recording a video as the SD card wouldnt get full?

does that make any sense at all?
Not really. The cable you've shown is a male to female extension cable. The only thing you could put at the far end is a micro SD card, unless you cut the end off and connect it to your hard drive somehow. (I doubt that's possible and there are better ways of connecting a hard drive.) Also note that an Arduino isn't suited to streaming video, as its clock speed is too slow.
133  Community / Bar Sport / Re: Is it just me, or.... on: July 03, 2014, 11:54:51 pm
The Kwipke Kwippler.... now THAT was a wobot.

(Ok, not so much a robot as an RC, but still.)
The products sold by ACME Inc. are far better. Meep meep!
134  Community / Bar Sport / Re: Students caught out.... on: July 03, 2014, 11:47:47 pm
Anyone tried this?

http://www.dx.com/p/klt-982a-solder-paste-glue-dropper-liquid-auto-dispenser-controller-black-230312#.U7RhF-2sCCw

I'm looking into a solder paste dispensing thingy.  That one's relatively cheap.  On the downside, it looks relatively cheap.  Also looks like it needs an external air pump.
Did you notice that it needs a 220-240V 50Hz power supply? It may not work on your 110V 60Hz supply.
135  Community / Bar Sport / Re: Is it just me, or.... on: July 03, 2014, 11:30:56 pm
My favourite question is "I am designing a traffic light system..." as though it's a project they have set themselves.
They stop posting that at the end of term [semester]. We'll get a 6 week break shortly.
Quote
It also shows how many people just ask a question without at least trying to use the Search facility.
The blink without delay example is the favourite for that.
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