Question: Is a negative ATX supply rail considered logic low in regard to activating a transistor?
Background: As a budding electronic hobbiest, I must admit I am flustered because I haven't been able grasp a clear understanding of negative DC rails, Zero Volt rails & their relationship in circuits. I understand the swing associated with AC & the concepts of positive grounds used in the past by the automotive industry. But this DC question eludes me.
The answer will help me understand the solution I need to come up with in regard to a Project Forum thread I posted about a fuse circuit indicator for an ATX PS conversion. Having pretty much resolved the positive rail circuit (I hope), the question I last posed regarded the negative rails. I'm stuck until I really grasp this voltage concept. I think the solution lies in an NPN transistor to flip the logic for the PNP, but I'm not confident about it.
As always, thanks for the time & any suggestions.
Background: As a budding electronic hobbiest, I must admit I am flustered because I haven't been able grasp a clear understanding of negative DC rails, Zero Volt rails & their relationship in circuits. I understand the swing associated with AC & the concepts of positive grounds used in the past by the automotive industry. But this DC question eludes me.
The answer will help me understand the solution I need to come up with in regard to a Project Forum thread I posted about a fuse circuit indicator for an ATX PS conversion. Having pretty much resolved the positive rail circuit (I hope), the question I last posed regarded the negative rails. I'm stuck until I really grasp this voltage concept. I think the solution lies in an NPN transistor to flip the logic for the PNP, but I'm not confident about it.
As always, thanks for the time & any suggestions.