UPS for 12V DC ?

Can you explain how such a design would function? I'm eager to hear.

I don't see the relevence.

I envisage a setup something like this:

+12V ___|____ input| | output -----------| circuit|----------._/| |________| |_ | phone line | | \\| ---------------+---------------' | 0V (not grounded) You seem to be of the opinion that such a thing is unworkable. why is that?

Bye. Jasen

You are correct in that assessment. I think it would be more to the point that you showed me that it could work. Let's start out with a simple question. In your drawing, which is tip and which is ring?

I intended 0V as ring but that really depends on who wired the socket. and the device would probably have a diode bridge between the input and the phone line to sort out that ambiguity, which would put the 0V at nearly 48V below ground before the phone line starts to ring.

Bye. Jasen

Ah, according to your diagram, the input *is* the phone line. I find it odd that, given your previous cautions against monkeying with a telephone line, you've done exactly that with your completely ambiguous "circuit." At any rate, you've shown me that you have no clue about telephony, and have some strange and unworkable ideas about electronic design, so I see no reason to continue.