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1  Using Arduino / Project Guidance / Re: motion sensor - LED Detection System for baby Safety in Car on: September 10, 2014, 12:29:20 pm
...But it's picking up something produced by a LED.  That's exactly 1/2 of the equation to a working IR optocoupler.  Optocouplers are often single piece units that contain both the LED and the detector in one unit.  You and I both know how they work.  But as a whole, that unit is still marketed and sold as a "sensor".  Just saying.
2  Community / Exhibition / Gallery / Skeleton Banjo Band on: September 10, 2014, 11:37:24 am
I didn't build this band, but I did get to install my MonsterShield on it and programmed it for a pumpkin farm.  My MonsterShield basically plugs into an Arduino UNO.  Each band member is controlled by a double-acting pneumatic cylinder that is controlled by a 12 volt solenoid which is controlled by a relay connected to the MonsterShield.  I programmed the animation using my detachable keypad option (which connects to the MonsterShield with a standard ethernet cable).  Basically you press the record button and you begin pressing and releasing the output buttons which controls the relays.  The MonsterShield records what you do in real-time to an external EEPROM chip.  For this band, I used "overlay" recording, which means I recorded each band member one at at time, laying down the "tracks" one after the other. So basically I recorded 4 times and it was done.  The MonsterShield also has a Windows -based software graphical editor that allows you to edit animations and then upload/download them to the MonsterShield but I didn't do any editing on this.  I just downloaded the animation when it was done for safe-keeping.  If I knew this song a little better, I would have been more spot-on with the singer.  And I could have adjusted everything in the editor afterwards but this was "throw-away" because they are going to re-do the animation once they have the actual banjo music they plan to use.
3  Using Arduino / Project Guidance / Re: motion sensor - LED Detection System for baby Safety in Car on: September 10, 2014, 11:12:30 am
Depends on how lose you are using it in your definition.  LED's are often used as a 2-part sensor solution.  They can be used to emit light on one side (usually IR) and then picked up on the other side by an IR detector.  Commonly used for break-beam sensors, encoders, etc.   Also proximity detectors shoot IR light by LED's and measure how much IR is reflected back to a sensor to determine distance.
4  Using Arduino / Project Guidance / Re: Five proximity sensors with five RGB leds on: September 08, 2014, 11:53:40 am
I was just about to recommend NeoPixels.  You can buy individual NeoPixels and daisy chain them together.  They only need a single digital I/O pin to control.  You can set the color / brightness of each pixel individually using Adafruit's library.
5  Using Arduino / Project Guidance / Re: Expressions used with Rotary Encoders on: August 13, 2014, 11:12:51 am
Well I can only partially help.  The first thing to know is there are different types of rotary encoders.  They do not all work the same way.  The most common rotary encoder are sometimes called "gray code" encoders.  They have 2 pins that are pulsed based on which direction you turn the encoder.  If you turn it one way, the pin for that direction pulses for each step it is turned.  If you turn it the opposite direction, the other pin pulses for each step in the turn in that direction.  Your micro has to count the pulses from both pins and increment or decrement some variable accordingly.  Steps per revolution refers to how many pulses you get in one complete 360 degree rotation of the encoder.  So a 16 step encoder has 16 steps in one 360 degree rotation and a 48 step encoder has 48 steps (just to name 2 examples).

There are other types of encoders that actually output values by using different combinations of highs and lows across multiple pins.  There are encoders that count in hexadecimal, octal, binary, etc.  The datasheets for these usually have a table that shows you what value corresponds to each combination of pins.  There are usually more pins on these kinds of encoders. 
6  Using Arduino / Project Guidance / Re: New Project Help on: August 13, 2014, 10:57:27 am
Sorry to hear about your mom.  I recommend doing a search here and on the Internet... this is a question that has come up at lot.  One thing you're missing from your kit:  You'll probably need some optoisolated relays that handle a decent amount of current and amps.  You'll need these to switch on the generator and to engage and release the starter.  I'd recommend the 4-relay module from Sainsmart because it's only about $10 and it already has optoisolators on it and the relay contacts are rated for 125VAC and 30VDC at 15 amps.
7  Using Arduino / Project Guidance / Re: RC car hack on: August 13, 2014, 10:48:19 am
One problem is that if you measure the voltage across the transmitter pots it is probably 9V.  In order to use a digital pot you would need to find a digital pot that can operate at that voltage. Otherwise you will have to use RC servos to move the gimble sticks. or turn the pot shafts. That is the first thing you need to do. If you cannot control the stick position with an RC servo then I don't know how to hack it.
If you can get that part working the rest is fairly straight forward. Use the Servo Library to control the RC servos.

Probably a moot point since the transmitter in this case has no pots... but I have looked at several RC toy transmitters and the voltage on the pots was not 9V but 5V on the ones I looked at.  All the ones I've messed with had voltage regulators on them.  Cheap ones that look just like regular transistors and have no heat sinks of any kind.  I've even seen one that had 3 of them.
8  Using Arduino / Project Guidance / Re: What products do I need to order? on: August 13, 2014, 10:37:35 am
I could be wrong, but it sounds like you are trying to make a "war" machine to map out devices in range... for what purpose I wonder?
9  Using Arduino / Project Guidance / Re: Designing A Laser Tag System : IR Problems on: August 12, 2014, 10:44:34 am
So is this game being played in the dark or during bright, sunny days?  The reason I ask is sunlight has a lot of IR in it and can blind your IR detectors.
10  Using Arduino / Project Guidance / Re: Attiny85 led die. on: August 12, 2014, 10:20:41 am
Maybe you could make one with a ball bearing (that conducts), some wire, and a small section of straw.  Put both wires in one end of the straw so that when the ball comes in contact with them, it conducts.
11  Using Arduino / Project Guidance / Re: Remote Control Boat on: August 08, 2014, 01:39:45 pm
i have a lot of experience in this area.  I built a transmitter with an Arduino in it.  I started by hacking an existing HobbyKing 6 channel 2.4Ghz transmitter.  Originally the Arduino controlled the analog inputs to the transmitter board via digital potentiometer chips that worked off the i2c bus.  Worked great until one day the HobbyKing transmitter board went bad.  The 2.4Ghz radio module was still good, however, I learned that I could output PPM directly to the radio module using a single I/O pin.  The end result is this:

And here's a long build thread with lots of pictures, video, and iterations leading up to the final result:
12  Using Arduino / Project Guidance / Re: Read car AC display using Arduino on: July 23, 2014, 10:19:48 am
Careful!  You are doing things that can damage your Arduino!

The acc wire that supplies 12V... yes, it could be used to power the Arduino, but you should be aware that it can be a "noisy" 12 volts and might have voltage drops or voltage spikes.  Others have written about this.  Not sure what the best advice is for this, but in theory it should work.  I think I've read of others putting a voltage regulator in between the 12V and the Arduino to help save the Arduino from battery weirdness.

Using a 5V voltage regulator to drop a 12V signal for sense detection on an Arduino is not a good idea.  It is a really, really bad idea.  You should not do that.  What you should do is use an optoisolator as a switch.  Have the 12V signal switch the optoisolator on/off.  Have a digital I/O pin on the Arduino connected to ground on the Arduino.  So when the 12V signal is there, the switch is on, and current flows from the digital I/O pin to ground.  When the 12V signal is not there, no current flows from the digital I/O pin to ground.  Your use of a voltage regulator is just plain wrong.  You do not want to add voltage to an Arduino's input pins from another voltage source.  They aren't designed to do that.  A voltage regulator will generate heat by burning off the excess voltage as... well... heat.  It is designed to power something - not for using as an input signal.  It might work, but it also might fry your Arduino.

The analog pins on the Arduino are only designed for 0 to 5V.  The value you are getting is NOT voltage.  The value is a range between 0 and 1023, which corresponds to 0 to 5V.  So if you read a value of 512, that would be approximately 2.5V.

As for what you suspect is a data wire...  It's not likely to be a compatible serial signal that you can just hook up to the serial pins on an Arduino.  You would need an oscilliscope or a digital probe that actually capture and analyze the highs and lows to figure out the signaling and protocol.  Not something you can do without one, unless you can somehow find the specs on the protocol used.  And even if it was a TTL serial or RS-232 or RS-485 signal, tapping into it with an Arduino could affect the signal and make it not work.

Is the fan knob a potentiometer with 3 wires?  If so, your  best bet might be to disconnect the fan knob from the AC unit and instead connect it to the Arduino to read, then use a digital potentiometer IC (like the DS1308 for example) to send a digitally controlled output to the AC unit.  This would also let you override the fan setting from the Arduino.
13  Using Arduino / Project Guidance / Re: How to drive lights with a text file on: July 14, 2014, 12:35:13 pm
You mentioned "Word document", which I take to mean Microsoft Word.  You're not going to get an Arduino to read that.  You will want to use a plain text file, aka ascii file.  How do you intend to "feed" the file to the Arduino?  SD card?
14  Using Arduino / Project Guidance / Re: custom PCB on: July 14, 2014, 12:31:07 pm
Some advice for the "tombstoning"...  (By the way, I assume you meant 0603, or 0805, not 0803).  Are you sure you are putting down the right amount of paste?  Too little can cause problems.  Are you putting down paste unevenly --meaning 1 pad has way more paste than the other pad?  That's where most of my tombstoning happens.  I personally don't use an oven - I do all my surface mounts with a hot air reworking station.  Uneven heating can lead to tombstoning too, so maybe take a look at how your oven is heating the boards?  Finally... there is a glue you can use to hold the parts in place.  I forget what it's called, but it's usually reddish in color.  I've never used it, but one little tiny tab of that between the pads will hold your resistors and caps in place and prevent the tombstoning during reflow.
15  Using Arduino / Project Guidance / Re: Help design a system on: July 02, 2014, 01:43:00 pm
I can't remember whether it's from one of the Iron Man movies or RoboCop, but I remember a scene when they were demonstrating a suit and it malfunctioned, ripping the driver's lower torso off and kill him.  Think that was Iron Man.

EDIT:  It was from IronMan 2.  Oh yeah, and according Justin Hammer, the test pilot survived.  Lol.
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