I'm trying to build a project with a nano every soldered on a circuit board.
with these Components:
the LED is simmilar to this:
a reed Contact
and a few resistors
The whole circruit was working with a 12V power supply. But today the Chip got realy hot and it was not working anymore. Has somebody an idea, what's wrong?
Thankyou and best reguards
Lukas
Your Nano Every is a 5V board. If you power it with 12V, the on board regulator needs to get rid of ~7V x whatever amps you draw. This power comes off as heat.
can't you power it with 7V ?
Thankyou I'll try it,
is the other circruit okay? the Tech species of the board say 7- 21 V.
So I was a bit irritated.
Thankyou and best reguards Lukas
On the Arduino Nano Every there is a switching regulator, not the normal linear regulator where the excess power would come off as heat. I believe that while this is rated as a 1A regulator it can only supply about 500mA due to thermal considerations. So this is not an issue unless the board is damaged in some other way. Or the OP has been trying to pull more that half an amp from the 5V pin.
@lukas-arduino
Your schematic shows resistor R LED = 20000 ohms. Is that correct?
Or is it something smaller?
ah good point, I just assumed they had been cheap... I stand corrected.
thx, I learnt something 
It's a bit smaller but high to dimm the LED
Best reguards Lukas
It's a bit smaller
Well, maybe that's why your nano burnt out.
how big is the maximum Value I can use?
Thankyou and best reguards
Lukas
You want to know the smallest not the largest, so that you don't draw too much current.
For the Green, 200 ohms would be the smallest I would use and 1000 the largest
For the Red, 300 ohms would be the smallest I would use and 1000 the largest
I would also power the transmitter and receiver from the 5V output not the 3.3V
Well when driving two LEDs each on needs to have its own current limiting resistor.
Yes you should not power it with anything else.
Note 1: The board name can’t be both Nano 33 and Nano Every. I assume Nano Every in this case.
Note 2: The resistor in the common cathode lead might work if the LEDs are never on at the same time, but is unusual. And at 20kOhm you won’t see anything anyway. Use 2 resistors (possibly different values for proper visibility) between Outputs and anodes.
Note 3: You use a reedcontact between 3.3V and a pulldown resistor that you named pullup. The reedcontact works well if connected between Input and GND, using the internal pullup resistor (mind the inverted action).
Note 4: The transmitter module can’t take 5 volts. You supplied 3.3V (correct), but the input should not exceed the supply. You might use a voltage divider 1kOhm/1.8kOhm. It’s possible that you’ve fried the transmitter with that 5V. Just hope you didn’t fry the Output as well.
Note 5: You supplied the receiver module with 3.3V which means that it’s output may or may not get high enough to trigger the Input of the Nano Every. Supply it with 5V.
I’m not a hardware guy. Why would the maximum matter ? My crude understanding would be that the higher the current limiting resistance the lower the current - you to a point where the LED does not turn on at all.
Is there a risk for the Arduino if the resistance is too high?
Basically it would not.
The LED will turn on with any resistance but the brightness might be below the threshold of detection of the human eye. This would require adapting you eye to dark conditions like in astronomy, or again like astronomy, taking a long exposure photograph.
Ok thx
Wouldn’t the voltage drop across the resistance have a role on the diode threshold ?
(My understanding is that the forward voltage of the LED is the voltage at which it begins to conduct current and emit light and to properly light up an LED, the supply voltage must be higher than the forward voltage)
Not really, it is the voltage that causes the diode to emit, once it is emitting then the resistor limits the current it will take. That resistor would need to be very big to limit the emission of photons to zero. You could calculate it from plank's constant, but quite honestly it is not worth it. I suspect quantum fluctuations would cause the odd photon to be emitted. Or even quantum tunneling.
Yes, and so it is. The forward voltage drop is only in the order of 1.5 to 3V depending on the LED's colour. So 5V is way greater than this.
thanks
