I’m building a start box for a small turbine engine around an Arduino MEGA.
It comprises :
- Arduino MEGA
- Relay boards (with optocouplers)
- LCD 4*20
and the different voltages / needs are supplied by :
- 12V Battery
- 300W DC-DC (to lower to +6,5V)
- 7805 module for +5V
Now for the problem :
When I’m using the H-Bridge to fade a LED Strip I have at the output (maybe 1-2W, nothing serious), if the arduino is fed by the 6,5V, the H-bridge will barely light up the LED.
BUT If I plug the arduino to the USB, it will work fine and the LED strip will light up!
I measured the voltage on the power terminal screws of the MEGA (I have a sensor board) and it shows around 4,5V while connected only to the battery (which delivers perfect 12V and enough Amps also) and goes back to a nice +5V when I connect it to the arduino.
I also noticed that when one (or more) of the relay is working, the LCD backlight will lower.
I can’t be putting my 7805 through it’s paces? Could I? If I’m correct I’m only asking for 2-300mA in the worst case and it’s rated for 1,5A…
Enclosed is the schematic of my build.
Thanks for your help!