diy didi
Member
Hi.
I have built many fan and relay control circuits with opamps and comparators with relative success. But I always wondered about one thing:
Can the relay or cpu type fan be powered from the same rail as the opamp or comparator supply pins?
I see many circuits online where the opamps are run off of a 78xx or zener regulator to keep the circuitry on its inputs noise free and stable. Then the current drawing component such as a fan or relay that is being switch on or off by the opamp via a transistor, is sinking its current from the positive rail BEFORE the regulator .
Is this a general rule? I would like to know so that I dont make the same mistake again.
I have built many fan and relay control circuits with opamps and comparators with relative success. But I always wondered about one thing:
Can the relay or cpu type fan be powered from the same rail as the opamp or comparator supply pins?
I see many circuits online where the opamps are run off of a 78xx or zener regulator to keep the circuitry on its inputs noise free and stable. Then the current drawing component such as a fan or relay that is being switch on or off by the opamp via a transistor, is sinking its current from the positive rail BEFORE the regulator .
Is this a general rule? I would like to know so that I dont make the same mistake again.