Tool to test visible light sensors and IR sensors on their proper working and freqs in the nM range
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Video where I use this tester (19 june 2023) is here • Where can a White LED work? Used as sensor...
In this video I show a simple tool/electronic schematic with which you can test all kinds of light sensors on their properties. Be it Infrared or in the visible spectrum. The tool is a multivibrator working around 100 Hertz, that makes a LED (in the visible or not visible range of light) flicker on that frequency.
The human eye cannot discriminate 100 Hertz, so it looks like as if the LED lights up constantly.
But the sensor (IR or visible light) can surely detect that flickering, thus when you connect the light sensor to an oscilloscope, the oscilloscope will show the frequency of the multivibrator, sent out via the LED.
Barrier voltage of different color LEDS? Study the mathematics and theory, has a direct relation to the quantum physics. Perhaps more info on the www but surely in scientific publications from the 1960's up until now, 2023, about the principles of these specific semiconductors (LEDS) and their materials from which they are/were made.
I used the most simple circuit to do the work: the 2 transistor Multivibrator (Muvib). In this case made with 2 times a BC 549 C (very high current amplification, in the order of 500 x). But you can also use other NPN small signal transistors (say the BC 547 b, current amplification in the order of 250 x), because the circuit is absolutely not critical.
The capacitors in the Muvib are for a big part responsible for the frequency, here around 100 Hertz. When you want another duty cycle/frequency, change their values. Say in the order of 100 N = 0.1 uF (always non polar, at least here) to 470 N (=0.47 uF) or even a higher value, say going to 1 uF non polar.
When you take lower values for the capacitors, the circuit will go to the 5000 Hertz-8000 Hertz range. Thus: say with two times a 10 N (= 0.01 uF) capacitor. Could be that you want and need that frequency for testing IR or other light sensors.
Third (most recent) video is here (29 may 2023, about LEDS and their spectra) • About LED's (Light Emitting Diodes), their...
Second video is here (28 may 2023, how a computer mouse works) • How an IR sensor unit of a computer mouse ...
First video is here (23 may 2023, talking about electronic sensors) • Talking about electronic sensors for visib...
In general: Infrared light can be used to determine chemical substances (chemical bonds inside materials). Is that a simple thing to make such a unit? Yes and no.
You need a fierce IR source, covering the complete IR range, from the high to the low frequencies (nM range). Normal glass blocks IR frequencies (at least a big part of them/in the spectrum) so quartz glass or certain plastics must be used in such a setup, thus materials that are transparent for IR light.
For the other part: there must be a scanning tool, shining IR light (from high to low nanoMeter = nM frequencies, or reversed) on the chemical substance and at the same time the absorbance on all the frequencies in the nM range must be stored and/or reproduced on a computer screen.
That is what is going on in a spectrophotometer. Much more info is on the www.
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Sorry that the video suddenly stops (!) but I had a telephone call. Everything important was told, by the way. Upload 2 June 2023.