Switching Negative Voltage
Molitor
Posts: 2
This may come across as a silly question but is there any difference switching negative voltage with a transistor? I'm familiar with TTL level stuff so may end up building it just to see if it works but here goes...
Basically I need to emulate a peice of hardware that currently bit bangs on a serial port using -12v DC to activate relays. (I have to use -12v or I'd just switch it all over.) My plan is to just use ULN2003AN (or I could use 7 2N4401 instead) to switch the -12V (which I was planning to use a TC7662A to produce from a 12v DC source [noparse][[/noparse]which also powers the stamp via a MIC2950]).
The little I've read (and understood) about negative voltage I see some references to NP/PN boundries and fusing that leads me to believe I might just roast the transistor(s) by doing this. Any sudgestions?
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Basically I need to emulate a peice of hardware that currently bit bangs on a serial port using -12v DC to activate relays. (I have to use -12v or I'd just switch it all over.) My plan is to just use ULN2003AN (or I could use 7 2N4401 instead) to switch the -12V (which I was planning to use a TC7662A to produce from a 12v DC source [noparse][[/noparse]which also powers the stamp via a MIC2950]).
The little I've read (and understood) about negative voltage I see some references to NP/PN boundries and fusing that leads me to believe I might just roast the transistor(s) by doing this. Any sudgestions?
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