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1231  Development / Other Hardware Development / Re: My first pcb on: February 28, 2013, 12:50:12 pm
You need to post the schematic.

I'm not familiar with the program you're using here, but if possible you want to fill the board with a ground plane to take heat away from the regulator. At worst you can do it manually by just adding a lot of extra, thick traces. Also, that regulator needs capacitors (typically electrolytic) on its power in and power out lines; if you don't include them your power will be fruity. You can always leave the spaces unpopulated if you find that you don't require them -- but can't add a capacitor if you find out you need them and don't have a space available!
1232  Using Arduino / Project Guidance / Re: Controller for rc flight models like helicopters, quadcopters and tilt-rotors on: February 26, 2013, 08:47:39 pm
That KK2 board is getting pretty dated. The gyros are old school piezo and it uses an ATMega168 which is too small for the newer firmware. That's why Seeed has it on closeout.

This board uses a MPU-6050 (acc + gyro) and is compatible with MultiWii which supports pretty much any configuration you can think of.
1233  Using Arduino / General Electronics / Re: manual and smaple code for DFRobotics relay shield 2.1 on: February 26, 2013, 05:18:08 pm

Might not list your particular board but it explains the relay board genre very well.

You should anticipate that the relays will require ~100ma per relay when energized and that's why they need external power. If you look up the specs for the particular model relay (google the part number) you'll get a more definitive answer.
1234  Using Arduino / LEDs and Multiplexing / Re: Led RGB with just two wires on: February 26, 2013, 05:15:41 pm
Example at
1235  Using Arduino / Project Guidance / Re: Most accurate way to measure speed of a car on: February 26, 2013, 12:33:03 pm
Calculating speed using an accelerometer would only be accurate for a few moments off the line. The only practical way is to use GPS.

In a previous discussion someone mentioned that car manufacturers are required to configure their speedometers to never report slower-than-actual speed and that they have to be accurate to within ~10mph? I know on my car that it will report its speed ~30mph when actual speed is 20mph. YMMV (literally) if you try to use the car's speedometer.
1236  Using Arduino / General Electronics / Re: Control very high power LED on: February 26, 2013, 12:25:02 pm
50-100W IR led at 38Khz? Is this like a city-sized TV-B-Gone?.  smiley-mr-green

Linear LED current regulators (e.g. CAT4101, NUD4001) can be used in parallel for 3.5A control. Your efficiency would depend on keeping your voltage supply near your LED's Vf.
1237  Using Arduino / General Electronics / Re: can you take a look at my eagle pcb design? on: February 26, 2013, 03:17:40 am
Whoops I was totally oblivious to the fact that this is a shield.

Here's an example of a Seeed user that created a shield using their service and squeezed their pin holes right on the edge like you're doing. Worked for him so you should be OK.
1238  Using Arduino / Project Guidance / Re: Powering 1/2hp dc motor on: February 25, 2013, 07:56:14 pm
My point was that you already have variable speed in one direction. If you use a DPDT switch on the motor leads to reverse them then you can use the same variable speed to go in the other direction.
1239  Using Arduino / General Electronics / Re: can you take a look at my eagle pcb design? on: February 25, 2013, 05:41:36 pm
Seeed will allow the pads that close to the edge. The extreme would be castellated pads and that is possible with their service.

Not really a good practice though. You've got lots of board space and you should use it rather than creating physically weak areas on the edge of your board.
1240  Using Arduino / Project Guidance / Re: Powering 1/2hp dc motor on: February 25, 2013, 05:22:07 pm
Wouldn't it be a lot simpler just to throw in a DPDT switch so you can reverse the leads on the motor?
1241  Using Arduino / Motors, Mechanics, and Power / Re: Magneto interference with arduino on: February 25, 2013, 12:05:02 am
Make sure your engine has a "resistor spark plug". They should be standard on any modern engines but it's worth a doublecheck.
1242  Using Arduino / Project Guidance / Re: Measuring current from solar panel on: February 24, 2013, 11:46:40 pm
Atmel has an application note on battery charging. Starting in section 3.3 they start explaining the voltage and current measuring.

With respect to solar panels Tim Nolan's MPPT design is a must read.
1243  Using Arduino / Microcontrollers / Re: Arduino 1.0.3 - Arduino Uno and ATTiny85 problems (video included) on: February 23, 2013, 09:32:58 pm
First step should always to be sticking LEDs on pins 7/8/9. From the ArduinoISP code:

// this provides a heartbeat on pin 9, so you can tell the software is running.
uint8_t hbval=128;
int8_t hbdelta=8;
void heartbeat() {
  if (hbval > 192) hbdelta = -hbdelta;
  if (hbval < 32) hbdelta = -hbdelta;
  hbval += hbdelta;
  analogWrite(LED_HB, hbval);

Now you'll know if you've actually got the ISP sketch running. Anything else is guesswork.
1244  Using Arduino / General Electronics / Re: Compatible replacement for arduino nano crystal? on: February 21, 2013, 08:35:16 am
The board pictured is not an official Nano (it's made by "funduino").

As to whether or not the eBay resonator has the same footprint is hard to say. You'd have to look up the datasheet for the eBay resonator and compare it to the footprint on your board.
1245  Using Arduino / Project Guidance / Re: Fast boat rudder system optimization on: February 21, 2013, 08:03:20 am
Seeedstudio's wiki for their flow sensor provides examples very similar to what you're trying to do with your speed sensor.
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