I was working on the refractometer on Tuesday and my phone was out of battery and hence I have no pictures to share… YET!

To give everyone a summary:
Last night we got one of those 240VAC to 9VAC (dual rail) transformers from the boneyard and made a full rectifier along both rails (+9V and -9V gives 18VAC, rectified is the root mean square and smoothing cap).
That was put into a DC-DC converter to drop it to 4.9V and now runs the light in the refractometer.
Thankyou Simeon for setting up the transformer and full rectifier.
Thankyou Blair for donating the DC-DC converter.

Once the refractometer was setup correctly and turned on, it was missing a readout and the prism for setting the measure looks funky and I don’t know if it is working properly.
Opening up the refractometer I noticed a mirror had come loose in the enclosure, it was mounted back into apparatus using the double sided tape on the bench (Thank goodness it was their, life saver!)
This brought back the scales and readouts, however I lost the calibration while working on it (adjusted using 1 screw).

There was a problem with the light, it started blinking like as if the DC-DC converter was throwing an error, in hindsight I forgot to calculate what amperage the light was drawing and may be overloading the board. An extra resister to make sure the light is only drawing 0.3A should fix that. Then we just need to do a one point calibration of the refractometer and verify its results.
If there is no issue with the prism, then that should be it. Otherwise we can open it again and check what needs adjusting.

Pictures will be coming soon!


Also, here is some information/uses to help you get excited about what we can do once it is working:

Overview of Concepts:

Measuring CNC coolent:

Honey Quality:

Fruit Ripeness:

Beer Quality:

Water Salinity:

Battery Testing:

etc etc etc.
I want to do one on soft drink sugar concentration. But you should be able to see the trend.

Also, I wouldn’t mind playing around with testing car coolant, car oil, break fluid maybe even hydraulic fluid just to see if we can get anything interesting out of that. However most of those are better to test by other means.

Yesterday I grabbed some photos and installed that resistor before the light. It did not stop what ever error the DC-DC board was flashing about, however I still like it more with the resister there.
You can now see a generic overview of the circuit and my amazing horrible floating circuit :stuck_out_tongue:

This is an image of the inside where I re-mounted one of the misplaced mirrors

I will have a chat with Simeon about making a front surface mirror to replace the one that seems to be missing

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