Grumpy_Mike:
Let's say I run arduino on 9V DC buttery and my pedals are powered by 9V DC switch adaptor.
Can I still connect grounds together?I once tried to make a common power supply for a collection of five peddles for my son, to replace all the batteries. The result was that two of then went up in smoke.
It turns out that they have what is known as earth lift resistors in place to cope with common grounds on the signals. There was not a common power ground. In the end I had to make five small mains powered isolated supplies, one for each peddle.So beware trying to power two things off the same circuit. Test first to see that there is a common ground on the supplies.
Hello Grumpy_Mike,
Thank you for your input. I've been connecting several pedals to very same power supply in many years ( 30+). So it works.
There are many pedal boards ( Like Boss BCB60 or BCB30)on the marked where 3 or 6 pedals share common none isolated power supply.
http://www.bossus.com/gear/productdetails.php?ProductId=610
Of course I too think isolated power supply is best.
Still when all those pedals are connected in series they share common ground by their screen wire. Aren't they?
Rolland Boss power supplies unlike many others have +9V and ground swapped in the pin. If you connect wrong pedal to it that has no protection diodes it could result with the smoke.