Demystifying Laser Diode Drivers: Current Sources versus Voltage Sources Rev 2019

[@emilyay9938]

Amazing video! I appreciated the way you made this so comprehensible. This helped me so much!

[@andrewbeaton3302]

THANK YOU SO MUCH! YOU MADE THIS SO SIMPLE TO UNDERSTAND!! THANK YOU AGAIN!

[@Brandon-rc9vp]

Thank you so much for sharing this information!

[@lambda4931]

Thank you! Good info Subcribed How do you switch the transistor in your high speed example that you discuss at about 14:12 minutes into the video?

[@toddanonymous5295]

excellent tutorial.

[@Rtube-b1l]

Good finally a video that shows me how I can run a pulse laser diode. I bought a cheap 75w 905nm diode thinking I could drive it off a buck converter. Then I saw that I needed to pulse it at 100ns max which is extremely fast. Now I maybe able to build a circuit which is good because pulse drivers are very expensive. Any thoughts on what parts I will need ?

[@hernanbenitez5361]

Good afternoon, I really like the explanation of the current sources. I wanted to check the following. In the last part of the talk, he indicates that one can have a laser diode with an operating voltage of 4 Volts, but the current source (or voltage source) is going to supply 12 V. If I understand correctly, what it says is do the 8 volts fall on the mosfet? And that's why you have to take a good look at the voltage operation in the transistor. I conjectured with the naked eye that if one feeds a 4 V diode with 12 Volts and a mosfet, it ends up burning it. have I understood correctly? is the excess voltage absorbed by the mosfet? Thank you very much for your video. Greetings from Argentina.

[@tabingwaalizik]

can I build continuous work laser pointers for sensor illumination

[@melangkoh4184]

hello Mister, can you tell me how to calculate which capacitor to use in a laser driver? someone gave me a plan and there was written i shall use a 47mF cap, but id like to know how to come up with this by my own...

[@ZeroMass]

use a scope and adjust accordingly.. Caps on the output of a switching driver really depend on how ugly the signal is.

[@melangkoh4184]

@@ZeroMass i dont know how to scope, i just got a plan for a simple laserdiode-driver, and theres a 47mF cap in the scheme, i just wanna know why its 47 and what happens, if i use a bigger or smaller cap?

[@ZeroMass]

@@melangkoh4184 if you plan on builds using diode lasers and are making your own driver circuits, it's a good idea to pick up one of the hobby grade 20$ scopes on ebay. Start with the ic of your circuit, look up the datasheet and they usually have exams circuits. Depending on the driver and how clean it's output is, determines how much filtering you would add The goal is low ripple, and overshoot.. these will degrade and or kill your diode. What wavelength laser are you using? Some are more robust than others... Also what type driver? Switching boost / buck type or linear? Number one thing is use only a constant current based driver..

[@melangkoh4184]

@@ZeroMass kzbin.info/www/bejne/e2GuqnyGbrechKM thats the video that gave me the idea..ive actually ordered some more expensive drivers weeks ago..but im planing on building this thing just for practice. I just wanna know how he came up with the number 47mF. A Multimeter doesnt incolde an oszilloskop, does it?

[@ZeroMass]

@@melangkoh4184 that's an lm317 in constant current mode. It's a linear regulator, so if you use with batteries, a small cap on the input and output is fine. Be very careful with that build if you are using the 450nm 1W diodes. A simple reflection off a white wall in close proximity WILL damage your eyes . You first need proper OD4 goggles.

[@himanshuful]

Well Ohms Law is not about Current Inversely proportional to Resistance. Current is proportional to Voltage across element. The Proportionality constant is Transconductance which should be Constant, otherwise Ohm's Law is invalid i.e. I must be linearly varried with V for ohms law

[@electrolance7505]

v=ir only works perfectly for linear devices. That's why in school they start with passive device and ohms law

[@One-jz6sl]

But, but... for a given load or resistance, a higher voltage causes more current.

[@RoyAndrews82]

But the capacitor will take forever to charge.. so you need a bank of capacitors to make up for the amount of time it takes for the power supply that charge the capacitors... So technically I guess capacitors in parallel.. multiplying the voltage with each capacitor added..

[@thewealthand_health]

Thanks!

[@AvishekDasPostdoc]

Greattt

[@shawnli6745]

讲解的是恒压和恒流的基础，干货不多。

[@theRealDonaldTrump666]

i know your giving factual information and i dont want to be that guy but your initial example is only true under specific conditions. if your 100 v source only has 50 mA of current a 1 ohm resistor will not make it 100 A. i know its disappointing because i found a could 2 watt 1 ohms resistors hiding in battery chargers and thought omg i can take over the world now but alas current equal to the voltage did not manifest because the batteries could not supply that current. from what i can tell while you can get proper current / voltage limiting resistor values from ohms law with batteries its less useful and with transformers or inductor driven power supplies its more relevant but the 1 ohm resistor still faces the conflict between ohms law and reality. i have a voltage at a set potential and that potential has a max voltage and max current and given the resistance you get a value between those 2. it can be more voltage and less current or more current and less voltage. im sure smart people could phrase this all better but this is my experience

[@alma-bf3os]

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