Maker Pro
Maker Pro

Phone line interface: Replacing a 1:1 transformer with an optocoupler

J

Jim Thompson

Jan 1, 1970
0
should work.

If you put the resistor before the bridge you can use 1N914
diodes for the bridge.

but ringing voltage can be over 100V (peak) andf if you shunt it you may
stop other devices from ringing.

it may be best to keep the bridge and put some sort
of current-limit in series with the resistor.

While we're discussing different approaches, how about a line-powered
blocking oscilator built on one side of an ethernet transformer
and an AM (or fm?) detector on the other side :)



Bye.
Jasen

I've often pondered, but never tried... has anyone tried to pick up
the signal from the CURRENT in the loop?

...Jim Thompson
 
M

Mark Zenier

Jan 1, 1970
0
If you'd asked in the right place, instead of adding to the clutter of
this cesspool, you'd get a very simple answer.

Michael, you sound like you need a vacation.

Anyway, if the OP is looking for an circuit example, the
October 1981 QST, reprinted in the 1991 ARRL Handbook for
Radio Amateurs has a optocoupler based phone interface
using several 4N28's and a couple of 741's.

Mark Zenier [email protected]
Googleproofaddress(account:mzenier provider:eskimo domain:com)
 
O

OBones

Jan 1, 1970
0
Mark said:
Michael, you sound like you need a vacation.

Anyway, if the OP is looking for an circuit example, the
October 1981 QST, reprinted in the 1991 ARRL Handbook for
Radio Amateurs has a optocoupler based phone interface
using several 4N28's and a couple of 741's.

Excellent! But how do I get a copy of this?
I'm not living in the US right now, and I'm not sure where to start
looking on the web.
Could anyone share a copy with me?
 
Top