I can run my sketch no problem when I power my Yun via micro usb and upload.
When I unplug the usb and then proceed to power my Yun via 12V through a L7805(5v voltage regulator), the sketch doesn't seem to initialize when it boots and the Yun onboard LEDs seem to flair up ~ every 10 seconds - I'm assuming this is restarting the Yun each time the lights flair up. Is the voltage regulator some how sending variable amounts of Volts to my Yun and causes it to restart continuously?
It is dissipating approximately (12-5)*0.3 = 2.1 W. While that is not a lot, if it does not have a heatsink it might get quite hot. This might get it into thermal shutdown and maybe causing what you see. Also what size of capacitor do you use at the output of the regulator.
I am using a switching regulator that is pin compatible with the 7805 quite successfully , it has a efficiency of 80-90%, so it dissipates less than 200mW.
I don't have a capacitor that is connected to my output.
I picked up one of these but I guess I overlooked its importance. The adafruit tutorial said to plug it into the the female dc adapter.
I don't really use an equation for the capacitor, it is more something I have empirically determined over the years. It is a matter of how much ripple you are willing to live with, and that also what the source of the power is. I also think that the 7805 likes to have a 0.1 uf on the input and output for stability.
A multimeter can tell if you have brown-outs, which is what I think you will be looking for here. It will not tell you the ripple, which might be an issue without the capacitors.
The middle pin of the voltage regulator goes to ground, right?
I just tried using the electrolytic capacitor, positive end to middle pin and negative end to ground. It made my arduino onboard LEDs fire off like crazy and the WLAN light wouldn't turn off. Did I out the capacitor in reverse?
mjmostachetti:
I just tried using the electrolytic capacitor, positive end to middle pin and negative end to ground. It made my arduino onboard LEDs fire off like crazy and the WLAN light wouldn't turn off. Did I out the capacitor in reverse?
i'm not experienced enough to be able to say definitively - i'm also more on the programming side and am quite ignorant with regards to electronics basics - you could ask over at the General Electronics section, there are knowledgable users there who would be better suited to guide you with definitive replies.
mjmostachetti:
The middle pin of the voltage regulator goes to ground, right?
that's also not definite, it depends on the component itself, if you don't have a datasheet, try searching for it - enter the code you see on the component - is it just L7805 ?
attached a pic of what you should be looking for; and here's a video to help
mjmostachetti:
The middle pin of the voltage regulator goes to ground, right?
I just tried using the electrolytic capacitor, positive end to middle pin and negative end to ground. It made my arduino onboard LEDs fire off like crazy and the WLAN light wouldn't turn off. Did I out the capacitor in reverse?
Yes, the middle pin should be ground, so looking at your second statement, the capacitor is connected from ground to ground, and should do nothing. It is sounding like the pin isn't really grounded. Can you show the circuit you are using?
So I've finally gotten it to work, but the Yun seems to sputter out after 5 or 6 cycles of my sketch. When I say sputter out, I mean it emits a little wizzing noise and then the power light on the Yun slowly dims to nothing.
When I plug the Yun directly into a 5V AC/DC adapter, it runs perfectly, but I need the 12V to power an LED strip.
I'm using a 330 pF capacitor on the V input of the 7805 and a 100pF capacitor on the V output.
There is no heat sink on my 7805. Could this also be contributing to the problem?
What did you do to make it work ?
Have you monitored the 5V when it 'sputters out'?
Have you measured the temperature of the 7805?
It would be good to get some of that information rather than guessing out in the blue. It sounds like the 7805 might be going into thermal shutdown, but who knows.
