DIY Arduino

This is my second project so I really don't know much. I built this project and when I power it up it works for about a minute then I start seeing some strange things. I have an LED hooked up to number 13, and the atmega is running the blink program. This project also has an LED for power. After about a minute of running the power led starts to flicker and dim then the Arduino seems to restart the program over and over. I have ran this on a 12 volt battery and a 9 volt battery with similar results. The 7805 seems to be cool to the touch.

The project calls for 2 Electrolytic Decoupling Capacitors - 10uF/25V When I ordered my parts I received a package marked 2 cap alum 10uf/50V. This is the only thing I can think of that may be causing the problem.

This is the only thing I can think of that may be causing the problem.

It might be but it is not an issue I can assure you. The voltage rating of a capacitor has no effect here. In fact the ones you receive will allow you to operate it at a higher voltage.

However like most instructables this is a crap circuit. There are no ceramic decoupling capacitors anywhere in the circuit.
You need a 0.1uF on each of the two power supply pins on the Arduino. And also one on Aref.

So when they say decupling capacitors that just means that they are kind of filtering the power and it doesn't have anything to do with the actual capacitor it self?

I have some ceramic capacitors marked 10 is that what you are talking about?

0.1uF, aka 100nF, are little ceramic caps like these
Get a bagful, you will use them with all ICs
http://www.dipmicro.com/store/C5K10-50

I just found out about switching regulators yesterday so I was hoping to get this thing working and change out the 7805 for a r-78e. This arduino has a real job to do out in a water proof box. When I finally figured out the sleep code I am getting 36 hours out of an 8 cell AA battery pack on my store bought Arduino. Maybe it would be best to just take the 1117 off of my store bought one and replace it with the r-78e. Then I could just scrap this junk circuit lol. I have been working on this project since November and I really need to get it out working for the summer.

and it doesn't have anything to do with the actual capacitor it self?

No it has a lot to do with the value in the respect that the value affects what frequencies it will filter at before self resonance, after which capacitors look inductive and do not have any effect. Read this:-
http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html

Maybe it would be best to just take the 1117 off of my store bought one and replace it with the r-78e.

No without ceramic capacitors your circuit will still be crap.

Hi,
Do you have a DMM?
It is essential when troubleshooting problems like you have at the moment.
What was the input voltage to the regulator when the flickering started?

Tom... :slight_smile:

Yes I have a multimeter. Input voltage is 11.54. Something interesting I put some wires on my 7805 and I noticed that the voltage is jumping around. Its going from 6.3 to 3.1. I added the ceramic capacitor to VCC pin and still nothing. Now the IC seems like it will not even start up. I put the IC into the stock arduino board and it fires right up. It seems like things are degrading.

I added the ceramic capacitor to VCC pin and still nothing.

You were not told to do that.

You were told to do:-

You need a 0.1uF on each of the two power supply pins on the Arduino. And also one on Aref.

I put caps marked 104 on VCC AVCC and AREF no change. I think its the 7805 I am going to go pick up a new regulator. The only one they have in stock is an NTE960 I hope that works. When I take the atmega out the power light still flickers it has to be the regulator I think. Ill be back soon to update if this doesn't work I think I am done. There is a lot of frustration that builds when you mess with things that make you feel dumb.

Hi
If the 7805 worked in the other board then you have a problem with your board.
Can you post a picture of it, both sides please.
Check with your DMM continuity and insulation of tracks on your PCB.

Tom.. :slight_smile:

I took the board apart. There was something wrong with it and I think it killed the regulator. I got the new one and it still did not work. I cut the 1117 off my arduino uno and put the NET960 on it and it works.

I have a R-78E5.0-0.5 on order and I hope it can make my batteries last for at least a week so I can get a good set of data. If not I am going to have to power this arduino with something other then batteries. I have it sleeping for 15 minutes between measurements and it was able to last 37 hours but that is still not ideal.

Hi,
Why don't you check this out. Gammon Forum : Electronics : Microprocessors : Power saving techniques for microprocessors
If you run the chip with internal clock, you don't need a regulator. You may power it directly from the battery.

I agree, run it off 3xAA batteries and power your project instead of voltage regulators.