Thanks a lot for your kind comment 😉

Do you made this?

Hi! This could be the next step and a second cuvette-holder for the reference-value I0...

@@stoppi kindly if you cam share your contact amd this project as well .... Please

Hallo! Ich habe das Gras bzw. die Blätter mit der Schere in kleine Stücke geschnitten, dann in Propanol (hatte ich noch von meiner Nebelkammer) gegeben und mit der Gabel eine Zeit lang zerdrückt bzw. zerstochert. Dann die Lösung durch einen Kaffeefilter und fertig ist die Rohlösung. Diese muss dann allerdings für die Absorptionsmessungen mit Propanol weiter verdünnt werden. Denn sonst sind die Absorptionswerte zu hoch und die Kurve sieht auch anders aus als gewollt...

Hi! To get useful results you'll always have to take the same amount of pH-indicator put to the water. Then I'm sure it will work. Good luck

Hello! X = 10 mm. I've bought cheap cuvettes from ebay: www.ebay.com/itm/4pcs-3-5ml-glass-Cuvettes-Cuvette-cell-with-Lid-10mm-10MM-I8F7-Package-Case-N2Y2/184632368956?hash=item2afcf25f3c:g:oTkAAOSwRMtgCx6T I haven't done anything to avoid reflections... Good luck with the experiment

Hello! I could have taken any other led too but I indented a higher absorbance rate and therefore I took a green led, because for this wavelength the absorption of potassium permanganate is higher and so its more sensitive for little amounts...

@@stoppi thanks for your answer. I have an other question. I want to determine the concentration of microalgae in water. I know that microalgae specifically absorb red and blue wavelengths and that these micro-organisms, being photosynthetic and due to some molecules they have, reflect the wavelengths that express the color green. Could I determine the microalgae concentration with a green laser light source? the spectrophotometer that I have planned to build is transmittance and I have a spectral sensor that will collect the data. I thought that by reflecting more green light, few green wavelengths would pass through the sample and thus I could determine the concentration of these microorganisms. Please tell me your opinion regarding what I am saying, and thank you for your attention

It's same with OD calculation?

@@dhanyrazorblade977 I believe so, since absorbance and OD [optical density] are considered equivalent. I am seeing that OD accounts for scattered light as well, while absorbance doesn't.

Ahh i see.. Btw, bro can you help me? I want to make OD meter with opt101 sensor and LED.. Do you have the arduino program to make it? So, in LCD can display Transmittance (T) and OD

@@dhanyrazorblade977 I don't have a code in Arduino to share - but check out projects in Instructables for similar applications. I use Labview for my work.

Hello! Thank's. The accuracy depends on the spectral width of the used lights/LEDs. If commercial photometers use a prism or diffraction grating and a line sensor they reach a higher accuracy than my apparatus.

Hello! At the moment I don't remember an other way without resistors. You can use Relais which are controlled by a microcontroller but this is in my opinion not a beautiful way... Good luck with your project, stoppi

@@stoppi I have another question, what the ICL 7660 is used for, is not very clear, or if have other options to do this?

Hallo! Ganz normale 8-pin IC-sockel wie zum Beispiel hier: www.ebay.at/itm/100-STUCKE-8-Pin-DIP-Pitch-IC-Sockel-Adapter-LottypTWKSPDEHEN/143869643846?hash=item217f4c8c46:g:~WYAAOSw0bJZqQeV

@@stoppi Vielen Dank für die schnelle Antwort!

Hi! I don't use any lens to focus the light. The distance between the led and the photodiode is just 2 cm and the liquid in the cuvette, which scatters the light is between them too...

You used black color holder??

@@dhakshath6142 The cuvette-holder has been painted black. And I used a short, black tube with inner diameter = 5 mm between the LEDs and the cuvette. Here you can see this plastic tube in the photo of the inside: stoppi-homemade-physics.de/photometer/

Thank you

Hello! With a RGB-Led you just get three wavelengths (red, green and blue). Only our eyes see for example yellow, when the green and red led is on. But there are no yellow photons, just red and green ones...

Hi! I use the software Theremino in combination with my webcam-spectroscope: ukposts.info/have/v-deo/jIBzZZqhoKdhzX0.html In combination with the photometer just to determine the wavelengths of my LEDs

thank you.

Hello! You can't use a white LED for a photometer because a white LED has a continuous light spectrum including all colours from blue to red. Therefore you couldn't say, which colours are absorbed by the liquid and which not. You have to use monochromatic LEDs with a narrow wavelength-width. Only then you can find out how much these wavelengths are being absorbed...

Hello! I have bought my LEDs at Roithner Laser Technik in Vienna/Austria. But you can also find LEDs with known wavelength on ebay or aliexpress. Better you check it with a spectroscope...

Do you have another wish? Sorry but I believe that my projects are more than enough documented including circuits, parts etc. Those who want to rebuild them have to contribute something too. But you can pay me 40 Dollar per hour for finding out the links you want to have...

It's the simplest code ever: stoppi-homemade-physics.de/photometer/