Відео

Dear delarosomccay Thank you very much for your comment about the values, the values are non-standard in the video, in my teachings I use a software called "diploma" to organize the problems. I randomize the values so that each students get different values on his own exam, so that the students cannot just copy from each other the answers. they have to go through the calculation to get the answers.

Dear simonlyons5681, Thank you very much for your comment. I do not quite understand the question, what is the 1mA current. what are the two LEDs, you use the two LED at the same time or what? what do you mean by the error? Please write your question in more details, I will get you back as soon as possible.

Dear shifra3203 Thank you for your comment, Yes, the prism angle is the same as apex angle.

Thank you for your comments, I learned this diagram from my father, I am using it for my students in Motion and Energy course, it helped my students a lot.

Dear RexxSchneider Thank you for your comment, your calculation is correct. Very good!

I disagree, the explanation is very important to show how this circuit acts as a current source.

@@mmh1922 Rubbish. My description above shows exactly how the circuit behaves as a current source and takes 30 seconds to read. Which part of it didn't you understand? Exactly what did you find missing that was present in the video, apart from all the unnecessary algebra?

@@RexxSchneiderI respect your right to express your opinion, however, as a reader, I decide what is important to me and what is not.

@@mmh1922 Of course you can decide whatever you want for you. And I can decide to call you out when you're spouting nonsense. Not for your benefit, naturally, but for the benefit of everyone else who reads your misleading comment and wants to decide if it has any value. That's why I asked you "Which part of it didn't you understand? Exactly what did you find missing that was present in the video, apart from all the unnecessary algebra?" Your inability to address those basic questions are surely the clearest indication to any observer that your initial comment was devoid of merit.

Dear Sir, Thank you very much for your comment. For your situation, you can choose the following: RE=0.5 Ohm (high power resistor). If you use a MOSFET, the voltage drop between the Source and the Drain normally will be 0.5 V, (less than 1 V) So the total voltage drop will be Vcc=2.7 V (laser diode) +0.5V (MOSFET) + (0.85A*0.5 Ohm) =3.6V. So, a single Li Ion battery (3.7V) is enough. As for MOSFET, you can use IRF540NF from Aliexpress, it is fairly cheep. Be careful, do not hurt your eyes from such a powerful laser. Wear a goggle in your project.

Thank you very much

Dear Nara49 Veera, Thank you very much for your comment. When I say that the circuit is no more working, when I_LED=14 mA, in the example, I mean the current was not kept the same as that flowing through a wire (no LED) or one LED, 41 mA. Ideal constant current source should keep the current constant no matter how many LEDs are there in series, always 41 mA, as in our example, but in reality such an ideal constant current source never exits, so It is necessary to tell how many LEDs can drive for a current source. We gave the formula in the video. In our example if the circuit gives 14 mA, (lower than 41 mA), we say that the source is no longer working, whether LED glowing or not is not relevant ! The key is that the current is out of control. Different LED has different properties, all we need is to supply the LEDs with controlled current I_LED. this is the circuit all about with formulas. Probably what you mean is that I should give a more realistic example with I_LED= a few 100 uA instead of 41 mA. If this is what you meant then you are totally correct. STEM Formulas

It is also interesting if you simply place a variable resistor to replace the LEDs in the circuit. When the resistance is zero, then the current through the resistor is 41 mA, when you increase the resistance of the resistor the current is kept at 41 mA for some time, when you increase further, the current drops. This is the usual behavior for a real life constant current source. Constant current source feels comfortable when the load is shorted, but it feels terrible when the load is open, R_load=∞, the voltage =I*R_load=∞, but the source does not have infinite voltage to supply! (whereas voltage source feels comfortable when the load is open, R_load=∞, but feels terrible if you short the output leads, in this case the current supposed to be infinite, but it can not deliver infinite current.)

@@stemformulas Then, perhaps, as the resistance increases beyond a limit, the current starts decreasing to support the supply voltage limitation. It is interesting. I will try to make a practical circuit when I get some time.

I am working on a video on PID algorithm (concepts behind the formulas and numerical examples with MATLAB).

I am very glad to hear that. To find schematics from circuit boards is a very enjoyable and challenging task.

Could you please re-type your question clearly?

@@stemformulas How do we use the normalizations condition to find C? (Translated from Hindi)

Please watch the video "Normalization of eigenfunction of momentum operator" on STEM Formulas

@@JyotiRani-pt3tr thnx could you sir explain

Dear Jyoti Rani, Thank you very much for your message, I was wondering if you could tell me the names of textbooks about Quantum Mechanics you are using?