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Topic: Isolating VCC in circuit (Read 2 times) previous topic - next topic

retrolefty


Ok, what am I missing here?  On the left is SFE's SPDT symbol.  On the right is their SPST symbol.   So, why can't I use the SPST switch?  Isn't it just a flip-flop between the two poles?  If the AVR is on the left, and the two poles on the right are one to the FTDI's VCC and the other to the PSU VCC?

The SPDT seems to have more poles than I need ...

What am I missing?


Your symbol drawing is trash. The one on the left is a DPDT and the one on the right is a SPDT. A SPDT (as drawn on the right symbol) is what will work for power switching on your board. The center terminal will become the board's +5vdc bus. The two other contacts will be wired to the USB's +5vdc and the external +5vdc regulators output.


Lefty

KirAsh4


Well to my mind the left one has two poles, it's a DPDT and the right one is a SPDT.


You're thinking is spot on with mine.


The SFE drawings are wrong ...


Wouldn't be the first time ...

KirAsh4


Your symbol drawing is trash.


It's SFE's symbol, not mine. :)


The one on the left is a DPDT and the one on the right is a SPDT. A SPDT (as drawn on the right symbol) is what will work for power switching on your board. The center terminal will become the board's +5vdc bus. The two other contacts will be wired to the USB's +5vdc and the external +5vdc regulators output.


Then, what I had in my schematic earlier is correct then.

retrolefty



Your symbol drawing is trash.


It's SFE's symbol, not mine. :)

Understood. But SFE means little to me, I just call them like I see them.  ;)


The one on the left is a DPDT and the one on the right is a SPDT. A SPDT (as drawn on the right symbol) is what will work for power switching on your board. The center terminal will become the board's +5vdc bus. The two other contacts will be wired to the USB's +5vdc and the external +5vdc regulators output.


Then, what I had in my schematic earlier is correct then.

Perhaps, it's a long posting thread, perhaps you could link again and I would be glad to take a look at it.

Lefty

KirAsh4


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