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16  Using Arduino / Project Guidance / Re: How to power 3 servos with one arduino? on: April 14, 2013, 12:20:08 pm
It's not a good idea to just supply a bit more power than you need. Overestimate then double that and your PS will live longer. Same with a PC, always get extra power supply.

But then on the flip side of that, when something goes disasterously wrong having a huge supply of current available, your circuit will turn to bacon long before the power supply trips whatever protection it has or blows open itself. I guess it depends on whether you want to replace the supply or replace your entire circuit. GoForSmoke indeed! smiley-wink

(Just teasing... it is a very good rule of thumb -- but consideration above is real.)
17  Products / The Arduino Starter Kit / Re: COMPLAINT: Starter kit components not fitting on: April 13, 2013, 08:36:55 pm
A bone regarding soldering?

You will need a soldering iron and some solder at a minimum. The solder is made of a metal that will melt at relatively low temperatures (relatively for metal). To get a good solder joint, make sure that you are heating both surfaces equally and apply the solder to the point where your two surfaces touch. The solder will melt and will flow along the metal. The reason for making sure that both surfaces are fully heated is that solder flows on hot surfaces, but puddles on cold surfaces. So, you would have a weak connection (called a cold solder joint.)

Generally, don't apply more solder than you need and only use solder meant for electronics (not plumbing or 'electrical' solder for eaxmple.)

Obviously the iron will get hot, so either buy a stand or an iron with a stand, and keep your fingers out of the way.

If you have the cash, get a good soldering station that has a temperature control. This is a tool that you will end up using quite often if you are getting into electronics as a hobby.
18  Using Arduino / Project Guidance / Re: Please evaluate and educate. First post on: April 13, 2013, 08:24:23 pm
You may not agree with that approach, but at the end of the day it is up to me to decide what advice or help I give, and you must do the same.

Absolutely. I apologize for getting snippy earlier. In general I was irritated with that sort of attitude (and I still stand by it) but looking at it later, I don't think your post was a good example of what irritated me. So, my apologies, Peter. I just managed to get my knickers in a bunch, that's all.

19  Using Arduino / General Electronics / Re: eagle CAD broad drawing - align parts on: April 13, 2013, 07:37:33 pm
By writing a script that places your parts for you, automatically. The only other way is to place them manually just as you described. All 60 of them.

A script is a better way to go.
20  Using Arduino / Project Guidance / Re: Send GPS data over Bluetooth on: April 13, 2013, 06:55:10 pm
Weird. Must have been something with the RF pattern. *Shrug* Glad you got it working.
21  Using Arduino / Project Guidance / Re: How to power 3 servos with one arduino? on: April 13, 2013, 06:28:35 pm
A single servo can draw 800mA when acting.

I was just reading that some can draw even as much as 2A!  smiley-eek
22  Using Arduino / Project Guidance / Re: Send GPS data over Bluetooth on: April 13, 2013, 06:25:17 pm
ps. It's not causing me any pain. smiley-wink Just you. lol
23  Using Arduino / Project Guidance / Re: Send GPS data over Bluetooth on: April 13, 2013, 06:24:34 pm
Try this:

Connect the bluetooth module power and the GPS up, but don't connect the bluetooth to tx and rx. Use the USB UART to test and see if it works that way. If not, the problem is probably power related.
24  Using Arduino / Project Guidance / Re: How to power 3 servos with one arduino? on: April 13, 2013, 06:22:37 pm
The servos would all be in parallel with the supply. So the voltage would not be divided.

Even one servo running off the Arduino supply could cause problems. It may run fine most of the time, but eventually you will have problems. And you will most likely have a lot of problems if you try to operate all three at once. For one, the current required could be high enough to overheat the regulator on the Arduino. It could also cause the voltage on the regulator to dip to the point that it resets the Arduino. If you are powering the Arduino itself from an external supply of 800mA or more, you *might* be ok with a servo or two. Over USB, you have only got 100mA possible.

Obviously the final application will be installed in the kitchen so you are likely going to be using a battery or a wall wart. Your servos can run off 7V just fine and the arduino can run off 7V just fine. So use the same supply to power both, but that means powering the servos directly from the supply, not from the Arduino 5V pin. If you use two separate supplies, make sure the grounds are connected together. Your supply should be rated for 800mA plus whatever the current of all three servos is. In reality, though, your arduino is unlikely to actually draw 800mA. So I think anything at least 1A would be fine.
25  Using Arduino / Project Guidance / Re: Send GPS data over Bluetooth on: April 13, 2013, 06:05:17 pm
Then I am just as stumped as you. There is nothing inherently odd about the connection to the bluetooth, and indeed that part is working. It can't be that connecting the bluetooth messes with timing because then the hardware UART without bluetooth wouldn't work either.

The only thing I am left with assuming is that the interference from the bluetooth is preventing the GPS module from working. Or possibly there isn't enough power for both?

Are you powering both modules off the arduino supply? Are grounds all connected together?
26  Using Arduino / Project Guidance / Re: Send GPS data over Bluetooth on: April 13, 2013, 05:15:30 pm
The only way I can see it interferring is that the GPS and blueooth are both operating on 2.4GHz. But I would expect that you would still get values from the GPS, but they would just be a bunch of errors telling you that it couldn't sync with a satellite.

I would go back and retry (without changing anything else) the normal UART. I think something has changed and I expect that it won't work that way either now.
27  Using Arduino / Project Guidance / Re: Send GPS data over Bluetooth on: April 13, 2013, 05:12:24 pm
It is def. my software serial that is having the issue. I have tried just using the GPS (software serial) and Arduino (UART) without the BT and this code works fine, but as soon as I add the BT I don't get the GPS data.

Those two statements don't quite mesh. The bluetooth is using the hardware serial (the same one you are checking without it) the GPS is on the software serial. As it is right now, you are not having problems with the hardware serial OR the bluetooth link or you would not be getting anything at all.

Are you sure something else didn't change between your test with the UART and with the Bluetooth?
28  Using Arduino / General Electronics / Re: PCB short circuits on: April 13, 2013, 04:58:22 pm
Thanks, all! I kept waiting to get an email telling me a new post had been made. When I didn't, I assumed there weren't any. Thanks very much for your excellent responses.

I have a multi-meter, and in checking circuits on my PCB, I found that there was no continuity in one of three 10K resisters. I'll pick one up at Radio Shack in a bit. I was wondering, though,
  • could that alone be the reasons for the shorts
  • could that alone be responsible for no power to the motor?

Using the continuity setting, you wouldn't get continuity on a working 10K resistor. Those (typically) only register low resistance around 50 ohms or below. Now, if you measured contuinity across the other two resistors, then you short is either in those resistors or whatever is connected in parallel with them.

Also, a resistor blowing open would generally not cause the event you described unless it were part of a current divider (resistors in parallel), in which case your damage would cascade until all resistors in the divider (in parallel) were blown open. It would do this before blowing open a trace.

Note: Assuming that you mean that you are using the continuity setting on a meter and not just the resistance setting. "Continuity" typically means a low resistance connection, like a piece of wire. It is meant to test for opens. It's not technically correct really, but it is how the term is used in practice.
29  Using Arduino / Project Guidance / Re: Send GPS data over Bluetooth on: April 13, 2013, 04:51:37 pm
That you are getting that readout says that your hardware serial and blueooth link is working, but it appears that your software serial is not.

Even at incorrect baud rates, you would still trigger this part:
    while (ss.available())
      char c =;
      // Serial.write(c); // uncomment this line if you want to see the GPS data flowing
      if (gps.encode(c)) // Did a new valid sentence come in?
        newData = true;

So, to see if it is even working at all, uncomment that line Serial.write(c) and you should be seeing it spit out the raw data being read from the GPS (even if it is garbage.)
30  Community / Exhibition / Gallery / Re: Build Marx generator with Arduino, need help on: April 13, 2013, 04:39:46 pm
I'm sure you understand this (I doubt you would have been able to build this if you didn't) but for the sake of someone else reading this, you would obviously need to multiply whatever reading the meter gives by 10.

And just so people don't think we are talking about just any resistors... and
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