T
Tim Shoppa
- Jan 1, 1970
- 0
OK, I've done optoisolation stuff before, but now for RFI reasons I want
to locate a receiver far away from a computer.
Isolation transformers were tried, but the capacitance between the windings
(something like 100pF) let way too much noise through in the 3-30MHz
region.
My bandwidth requirements are minimal (audio and a 1200 baud serial data
link). I really want to minimize the amount of digital noise (and stuff)
at the receiver end... putting a PC there is a complete no-no.
I see that Digi-Key has some fiber-optic receivers and transmitters for
very reasonable prices. For example, the Sharp GP1FA511TZ transmitter
and GP1FA511RZ receiver, which are a couple dollars for a pair
and have TTL-level in and out. But I have some really basic questions:
1. I can just turn the audio into PWM and run it over these, right? No
need for 50% duty cycle to the LED? In my head I'm thinking of these just
like the two sides of an optoisolator... am I too far off?
2. What's the optical interface of these parts? I see there are several-
hundred-dollar receivers and transmitters that use the same type of fiber
connectors that we use on network equipment at work. But these cheap fiber
parts seem to use a different interface - maybe one used in consumer digital
audio? Maybe they don't have any at all?
It looks like I can rig up a little fiber optic receiver/transmitter that'll
let me locate the receiver away from the computers for a cost of less than
$20 in parts... that'd be perfect, if I can pull it off.
Tim.
to locate a receiver far away from a computer.
Isolation transformers were tried, but the capacitance between the windings
(something like 100pF) let way too much noise through in the 3-30MHz
region.
My bandwidth requirements are minimal (audio and a 1200 baud serial data
link). I really want to minimize the amount of digital noise (and stuff)
at the receiver end... putting a PC there is a complete no-no.
I see that Digi-Key has some fiber-optic receivers and transmitters for
very reasonable prices. For example, the Sharp GP1FA511TZ transmitter
and GP1FA511RZ receiver, which are a couple dollars for a pair
and have TTL-level in and out. But I have some really basic questions:
1. I can just turn the audio into PWM and run it over these, right? No
need for 50% duty cycle to the LED? In my head I'm thinking of these just
like the two sides of an optoisolator... am I too far off?
2. What's the optical interface of these parts? I see there are several-
hundred-dollar receivers and transmitters that use the same type of fiber
connectors that we use on network equipment at work. But these cheap fiber
parts seem to use a different interface - maybe one used in consumer digital
audio? Maybe they don't have any at all?
It looks like I can rig up a little fiber optic receiver/transmitter that'll
let me locate the receiver away from the computers for a cost of less than
$20 in parts... that'd be perfect, if I can pull it off.
Tim.