01-12-2019, 06:26 PM
Below is my recognition of terminating resistance.
The resistance of this part is the part which must strictly follow the standard of "49.9Ω +- 1%".
The value of the resistance directly connects to the quality of the communication signal.
Originally, these parts is a part where the value should not be changed for convenience of the designer.
If do not comply with this rule, please see below for what disadvantages occur.
Impedance matching reflection:
https://www.google.com/search?biw=1272&b...reflection
For example:
https://electronics.stackexchange.com/qu...abit-ether
With such a communication waveform, the distortion further increases.
You need to be carefully that the part with such characteristics has been changed to "62Ω".
---
Parts I used "UT7500L-18-T92-B-K" do not seem to be selling for overseas.
There is no problem substituting with "MCP1702-1802E/TO".
For capacitors, first add a larger value, it is intention to get a margin.
For example: 10uF + 1uF(ceramic).
After that,
I think that it is a good approach to reduce while confirming the possibility of network operation.
First of all, it is important to confirm that it operates correctly.
If it does not work, everything you do is wasteful.
Perhaps, ultimately it will be okay only with 1uF(ceramic) on the output side.
---
> I have zero experience in soldering on SMD circuits...
The tools I use are not special.
It is a standard soldering iron. And I do not have "soldering station".
https://www.amazon.com/Hakko-temperature...B006MQD7M4
The solder material of the board is "lead-free", so it would be better to have flux.
For example:
https://www.amazon.com/HOZAN-Flux-H-722/...older+flux
If you are inexperienced, you can not go on suddenly, practice is necessary.
However, its difficulty is:
Anyone can do it by practicing about 1 hour using the junk board.
It's the level of difficulty above.
I will present a photo of the relevant part later.
Please wait for a while.
The resistance of this part is the part which must strictly follow the standard of "49.9Ω +- 1%".
The value of the resistance directly connects to the quality of the communication signal.
Originally, these parts is a part where the value should not be changed for convenience of the designer.
If do not comply with this rule, please see below for what disadvantages occur.
Impedance matching reflection:
https://www.google.com/search?biw=1272&b...reflection
For example:
https://electronics.stackexchange.com/qu...abit-ether
With such a communication waveform, the distortion further increases.
You need to be carefully that the part with such characteristics has been changed to "62Ω".
---
Parts I used "UT7500L-18-T92-B-K" do not seem to be selling for overseas.
There is no problem substituting with "MCP1702-1802E/TO".
For capacitors, first add a larger value, it is intention to get a margin.
For example: 10uF + 1uF(ceramic).
After that,
I think that it is a good approach to reduce while confirming the possibility of network operation.
First of all, it is important to confirm that it operates correctly.
If it does not work, everything you do is wasteful.
Perhaps, ultimately it will be okay only with 1uF(ceramic) on the output side.
---
> I have zero experience in soldering on SMD circuits...
The tools I use are not special.
It is a standard soldering iron. And I do not have "soldering station".
https://www.amazon.com/Hakko-temperature...B006MQD7M4
The solder material of the board is "lead-free", so it would be better to have flux.
For example:
https://www.amazon.com/HOZAN-Flux-H-722/...older+flux
If you are inexperienced, you can not go on suddenly, practice is necessary.
However, its difficulty is:
Anyone can do it by practicing about 1 hour using the junk board.
It's the level of difficulty above.
I will present a photo of the relevant part later.
Please wait for a while.
