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 » Home » The Project  » Creating Technologies  » Microbial Albedo Recorder

Light sensor

Light sensor

With this electronic circuit we aim to adecuate the signal coming from the light sensors (photodiodes). This will make the signal useful to real time adquisition and ionterpretation.

A photodiode can behave in tho very diferent ways, depending on the conection configuration: photoconductive or photovoltaic mode. We are interested in the first one, because it make posible a precise and stable relationship between the energy of the incident radiation and the output current.

The following figure shows the equivalent circuit used in the simulations and the caracteristic curve

Valencia wb circuit.jpg

Valencia wb graf1.jpg

Vmeasured = Vreal(Tj) + Verror(Tj1) + Verror(Tj2)

Figure 3. Compensation Subsystem.

In our particular case, we selected a J type thermocouple (Copper-Constantan), because one of its metals is copper already, and then there is only one extra junction in the connection.

Figure 4. Practical implementation.

Here we have:

Vmeasured = Vreal(Tj) + Verror(Tj2)