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photodiode configuration and signal mismatch

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Vasavi Sai
Vasavi Sai on 6 Jun 2020
Answered: Joel Van Sickel on 4 Aug 2020
Main aim, I want to transmit signal from LED to Photodiode. So I have designed a basic diagram in Simulink.
But it shows some error message that
Error compiling Simscape network for model untitled.
Caused by:
  • ['untitled/Photodiode']: Type mismatch in signal connection to W. Source signal type is {[1x1 double], 'W'} and destination signal type is {[1x1 double], 'W/m^2'}.
  • Light_Emitting_Diode.W = {[1x1 double], 'kW'}
  • Photodiode.W = {[1x1 double], 'kg/s^3'}
Please help me out to configure to match the signal.
Kindly refer to attached figure.
LED: 1) Battery 6V
Photodiode: 1) Battery 6V 2) Res= 100Ohms
Thank you

  1 Comment

Jyotsna Talluri
Jyotsna Talluri on 9 Jun 2020
Can you attch your model instead of sharing screenshot so that I can simulate and reproduce the error

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Answers (1)

Joel Van Sickel
Joel Van Sickel on 4 Aug 2020
Hello Vasavi,
your problem makes sense at it would seem those two blocks were designed to work together, unfortunately, they weren't. Those signals are 2 different units. The output of the LED is in watts, while the input of the photodiode in watts per meter squared. You need to divide the output of the LED by meters squared. you could do this using a PS gain block and set units to 1/m/m. However, you probably need to pick a small area for this to work.
Here is an example of a photodiode being used:


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