... | ... | @@ -51,7 +51,7 @@ Design |
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- sglux [SiC UV TOCONs / Broadband UV
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sensor](https://sglux.de/en/product-category/sic-uv-tocons/broadband-tocons/)
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- [TOCON\_ABC3](https://sglux.de/en/product/tocon_abc3-en/)
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- [TOCON\_ABC5](https://sglux.de/en/product/tocon_abc5-en/)
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- Gives 0-5V output
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- "Scatter" (tolerance) of ±20%. Should be able to calibrate this
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out.
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... | ... | @@ -61,23 +61,27 @@ Design |
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##### Calculation of required sensitivity and sensor
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- 1 MED/hr = 5.8 µW/cm² (from [Units](/uv-meters#units)).
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- Multiply by correction factor of 0.24 for a wideband TOCON ABC (that
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is more sensitive for UVA) to correct so that under natural sunlight
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- We want 0.2 MED/hr at 2V output = 0.5 MED/hr at full scale 5V
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output.
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- Scaling factor is 0.24 MED/hr/W/m² so we want 0.5/0.24 = 2.08 W/m²
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full scale
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- Correction factor of 0.24 for a wideband TOCON ABC (that is more
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sensitive for UVA) to correct so that under natural sunlight
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gives same reading in med/hr as a perfect erythema meter.
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- See [*Comparison of different UV sensors for use in an XP
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radiometer*](https://www.ohwr.org/project/uv-mask/wikis/Documents/Comparison-of-dierent-UV-sensors), A.
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Butterworth, December 16, 2018 (paragraph above Table 1).
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- 1 MED/hr = 5.8 \* 0.24 µW/cm² = 1.392 µW/cm² for wideband sensor.
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- Full display 199 mMED/hr = 0.199 MED/hr = 0.199 \* 1.392 µW/cm² =
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0.277 µW/cm² = 1.999 V
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- 5V TOCON should have max. irradiance at (5/1.999) \* 0.277 =
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0.693 µW/cm²
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- [TOCON\_ABC3](https://sglux.de/en/product/tocon_abc3-en/)
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max. irradiance (saturation limit) at 290 nm (peak
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wavelength) is approx. 1.8 µW/cm2
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Need attenuation of around a factor of 3, handling tolerance
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of ±20%.
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- 2.08 W/m² = 2.08e-4 W/cm² = 208 µW/cm²
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- The closest is ABC5 with 180 µW/cm² full scale.
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- 0.2 MED/hr would then give an output of 0.2/0.24 \* 1e-4/180e-6
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\* 5 = 2.3 V.
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- The tolerance of the TOCONs is ±20%, some of them may not give
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us the required output: 2.3V\*0.8= 1.84V instead of 2.000V.
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Should take this in account that 1.84V can be calibrated to read
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as 2.00V.
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- For comparison 0.2 MED/hr should give 0.79 V on the TOCON E1.
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- Assuming the powers that are quoted by sglux are in W/cm² are
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normalised to the sensitivity spectrum of the sensor.
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Likely not needed: digital calibration could be made with a [TOCON
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Adjustment board](https://sglux.de/en/product/tocon-adjustment-board/)
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... | ... | @@ -100,10 +104,9 @@ Adjustment board](https://sglux.de/en/product/tocon-adjustment-board/) |
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allows movement? Or wire the display up to the PCB?
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- Allow for hole in PCB to reach calibration screw
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- Resistors for the full-scale adaptation from 0-5V to 0-2V (1%
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metal-film)
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- Need attenuation of around a factor of 6, handling tolerance
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of ±20%
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- Tolerance of TOCON ±20%. Should be able to handle this.
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metal-film). Can be done with Vref.
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- Tolerance of TOCON ±20%. Should be able to handle this. Can
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be done with Vref. 1.8V should be able to read as 2.0V.
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- Use high-precision potentiometer?
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- Use selectable resistors?
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- Use a digital potentiometer or sglux setting
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... | ... | @@ -118,23 +121,8 @@ Adjustment board](https://sglux.de/en/product/tocon-adjustment-board/) |
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- 9V battery
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- Assembly: mask off the rightmost digit with tape or a dedicated
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sticker
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-----
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### Questions
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sglux
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1. TOCON can come with wires or a low-cost connector allowing assembly
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at 90 degrees?
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2. What is on the settings board? Digital potentiometer? Schematics
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available?
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3. Which TOCON
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Other
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1. Can TOCON be mounted on tilted top part of box?
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sticker. Or possibly not even needed as no UV will read as 000
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anyway.
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-----
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