hey,
i have a 5V relay module and LDR.
i wanna connect both.
LDR needs 5V right? and also the 5V relay needs 5V
um afraid to connect both devices to same 5V pin in arduino.
so i switched my LDR pin to 3.3V
thats not gonna damage my board right?
No, not necessarily.
1 Like
ooh! as my knowledge i think when I use 3.3V instead of 5V
I have some low luminance ranges, and that's the only cost of switching to 3.3V right?
You haven't told us anything about your circuit (or anything about your code), so my guess is the LDR is wired as one leg of a voltage divider.
1 Like
I don't follow.
With an LDR, you just make a potential divider across some known voltage; eg, the supply voltage.
You choose the other resistor in the potential divider to give you a sensible output over the range of interest...
1 Like
You also haven't given any details about what "relay module" you're using.
The "5V" might refer to the control signal, or the power to the relay coil - or both!
why?
1 Like
yes, i am using a voltage divider with10K resistor.
and 5v relay relay module
cuz of the current demand (I am not sure)
I just wanna know if its fine to connect LDR (yes, with voltage divider) to 3.3V or not?
Yes, of course it's OK.
It may not do what you want, but you seem unwilling to tell us anything.
1 Like
How did you choose that 10k value?
Your choice should have taken into account the supply voltage - it will be different at 5V and 3V.
A potential divider just gives you a fraction of whatever the supply voltage is - you choose the resistor values so as that fraction is suitable for the ADC input under the light conditions you require.
1 Like
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.