Class D low frequency amplifier integrated circuits are sometimes equipped with S / PDIF digital inputs. But these inputs are electrical, and the outputs of the corresponding standard for many sources (for example, sound cards) are only optical. To match them with each other, an optical input must be added to the microcircuit.
Instructions
Step 1
Check the documentation for your LF amplifier chip to make sure it actually has an S / PDIF digital input capable of TTL input signals. If you have already assembled an amplifier (or a device that includes it, for example, a mixer), disconnect it completely.
Step 2
Purchase a Toslink receiver module that is structurally combined with an optical jack (for example, TORX173). It is undesirable to use a module that is not equipped with a socket, since it is difficult to make the plug motionless without mechanical latches. And with the slightest shift of the connector, the light will be directed past the photodetector
Step 3
Fix the socket together with the module on one of the walls of the amplifier cabinet. If a device of the TORX173 type is used, connect its leads with numbers from 2, 4, 5, 6 to the common wire. Connect a ceramic capacitor of any capacity between the common wire and pin 3. Connect the +5 V power supply bus to pin 3. Connect pin 1 of the receiver to that pin of the amplifier microcircuit, which is designed to supply a signal of the S / PDIF standard with TTL levels. Other types of modules may have a different pinout.
Step 4
If there are no buses with +5 V voltage in the amplifier, assemble the stabilizer on a 7805 microcircuit. To do this, place it with the inscriptions facing you, and with the mounting hole facing up. Connect the middle terminal to the common wire, connect the left terminal to the bus with voltage from +8 to +15 V, and the right terminal to the power input of the photodetector. Shunt both the input and the output of the stabilizer with the same chains of two capacitors connected in parallel. One of them must have a capacity of about 1000 μF and an operating voltage of at least 25 V, and the second can be ceramic with any parameters. Observe polarity when connecting oxide capacitors.
Step 5
Connect the amplifier with an optical cable to the signal source. Power on both devices and check that they are working.
