I am struggling with understand this circuit in electronics class, and this video helped me a lot! Thanks for the thorough explanation, as well as the very nice animation, which contributed a great deal to me understanding it better. I've subscribed and will watch more videos :)
I was searching for a video that showed me calculations for this exact circuit! Thanks for the video! Btw, you probably get this a lot but your videos have helped me a lot in understanding mosfets, and circuits like this ect. 😃
theres a way using tip 41 to limit current at 1.5A 5V? the main source is 5v 2A but want to use it for etching metals and dont want to destoy the transformer temperature deviation should make it reduce the current at the load so theres no problem or i should choose the cheapeast way and just slam a 15w ceramic 3.3 resistor?
The input voltage is 310vdc, the output voltage will follow the load so I installed 40 LEDs for an output current of 100mA, will it last long and how does temperature affect the current?
Hi, if i need to make a laser driver costant current circuit as this, should i solder the LASER pole (-) to the "collector" (C) of Q1? And the Laser positive pole (+) should be soldered across R1 just like this video? Where do i need to add and solder some other component as a diode 1N4001 (for polarity protecnion supply) and a 10 uf capacitor? Thanks
This channel's name should be changed to Intelligent Engineer or Smart Engineer. This channel really deserves more than a million subscribers. What's your name dear friend? Where are you from? Pls do a video of yourself so that we can know about you.
Thank you so much for watching!! Please subscribe to our channel. My name in Parag and I am from Pune, India. Sure, I'll make a video showing myself when I reach 100K subs!
It's limited by the feedback loop between the two transistors. For Q2 to turn on, it's base needs to be biased on - ie. we need to get around 0.6-0.7V or so between the base and emitter. This requires sufficient current through R2 to produce that bias voltage. As the base current in Q2 rises, it's collector current rises, stealing current away from the base of Q1. If the base current of Q2 was to rise arbitrarily high, then it would eventually steal all of Q1's base current, turning it off, but then there would be no emitter current from Q1 to bias Q2's base on in the first place. Therefore, the circuit must operate in a delicate balance between Q1 supplying enough current to bias Q2 on and Q2 not stealing too much current and turning Q1 off.
A constant current circuit implies that you have a varying load which requires a change in the voltage as that load resistance changes. Therefore you cannot specify a fixed voltage such as 0.250 volts. Ohms law, E=IxR You must choose a maximum voltage for your circuit for practical purposes but then if your load resistance goes to infinity. Open circuit or no load, your current will no longer be greater than zero amps. A truly constant current circuit would require an infinitely high voltage when the load goes to zero or, more appropriately you would then be operating in an undefined, impossible condition.
Bruhhhh u r godddd at this point i really needed to know how current regulation is done and cooldnt find one till now
I am struggling with understand this circuit in electronics class, and this video helped me a lot! Thanks for the thorough explanation, as well as the very nice animation, which contributed a great deal to me understanding it better. I've subscribed and will watch more videos :)
I was searching for a video that showed me calculations for this exact circuit! Thanks for the video! Btw, you probably get this a lot but your videos have helped me a lot in understanding mosfets, and circuits like this ect. 😃
Glad it was helpful!
theres a way using tip 41 to limit current at 1.5A 5V?
the main source is 5v 2A but want to use it for etching metals and dont want to destoy the transformer
temperature deviation should make it reduce the current at the load so theres no problem
or i should choose the cheapeast way and just slam a 15w ceramic 3.3 resistor?
Excellent sir! Thanks for sharing!
How did you pick q1? Based on what parameters? What’s is an equivalent bjt?
The input voltage is 310vdc, the output voltage will follow the load so I installed 40 LEDs for an output current of 100mA, will it last long and how does temperature affect the current?
Hello, nice video ! can you tell which components to change (or even circuit) for a 5 Amps constant current source under 24V. Thanks.
Please don't use this circuit for 5A current.
@@FoolishEngineerWhich circuit should I use for 5 Amps?
how can the current in the load be consistent while turning off the Q1 transistor?
amazing explanatio ., what you refered for all this deep knowledge?? Pls share
Please check the description
Hi, if i need to make a laser driver costant current circuit as this, should i solder the LASER pole (-) to the "collector" (C) of Q1? And the Laser positive pole (+) should be soldered across R1 just like this video? Where do i need to add and solder some other component as a diode 1N4001 (for polarity protecnion supply) and a 10 uf capacitor? Thanks
You are very smart. Thank you for sharing this.
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it's a very good explanation thank you... Next time please explain CC/CV Regulator
I am waiting for that video too
Sure! On 5th July
This channel's name should be changed to Intelligent Engineer or Smart Engineer. This channel really deserves more than a million subscribers.
What's your name dear friend? Where are you from? Pls do a video of yourself so that we can know about you.
Thank you so much for watching!! Please subscribe to our channel.
My name in Parag and I am from Pune, India. Sure, I'll make a video showing myself when I reach 100K subs!
@@FoolishEngineer Pune people are really intelligent, especially in the matter of science and technology. Just like Germans.
nice videos ,i saw all your video .then which is best for driving LED considering temp stability .
Depends on your requirement of cost & accuracy
Great video sir, in your simulación you have a 1 micro farad cap, is this necesary, for oscilations os filtering?
Yes, for filtering
So, where did you get the hFE value of 50 from?
datasheet
this linear circuit is recommended only for 10amp max with calculation power bjt's and high power disipation.
Good explanation. Thank you.
I have a question. How base current for Q2 is limited? Because there is a lot of current available when Q1 is opened.
It's limited by the feedback loop between the two transistors. For Q2 to turn on, it's base needs to be biased on - ie. we need to get around 0.6-0.7V or so between the base and emitter. This requires sufficient current through R2 to produce that bias voltage. As the base current in Q2 rises, it's collector current rises, stealing current away from the base of Q1. If the base current of Q2 was to rise arbitrarily high, then it would eventually steal all of Q1's base current, turning it off, but then there would be no emitter current from Q1 to bias Q2's base on in the first place. Therefore, the circuit must operate in a delicate balance between Q1 supplying enough current to bias Q2 on and Q2 not stealing too much current and turning Q1 off.
@@brettski74 Thank you for your detailed answer.
sir plz guide how to make 0.9 A constant current output with high resistance
Good explanation and thank you, i need to make output voltage 250mV and constant current 35mA. Input voltage 9V. Please help me to build this circuit
A constant current circuit implies that you have a varying load which requires a change in the voltage as that load resistance changes. Therefore you cannot specify a fixed voltage such as 0.250 volts. Ohms law, E=IxR
You must choose a maximum voltage for your circuit for practical purposes but then if your load resistance goes to infinity. Open circuit or no load, your current will no longer be greater than zero amps.
A truly constant current circuit would require an infinitely high voltage when the load goes to zero or, more appropriately you would then be operating in an undefined, impossible condition.
Thanks bud! Can you do one with a BJT and MOSFET?
well, its similar. I have already made a video with MOSFETs, you can check that.
What Values must Be change in Order to get 200 mA output current ?
Lower the resistance of R2 to 3.5ohm.
Thx for everything
that u
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Hiii need 90v40 amas ccharger ❤
great!
useful video ..
please share LTSpice software download link
www.analog.com/en/design-center/design-tools-and-calculators/ltspice-simulator.html
@@FoolishEngineer Thank you sir
👍👍
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