LED Current Controller - Dimming/Brightness (BJT Constant Current Limiter)

Рет қаралды 34,834

4 жыл бұрын

Why drive LEDs with constant current? How can we limit current with 1 transistor and 3 resistors?
CircuitLab circuit: www.circuitlab.com/circuit/n6...
In this video tutorial we are going to be building a current controller for and led by using a BJT or bipolar junction transistor. We briefly talk about the relevant properties of a BJT, and then walk through several simulations in order to determine the correct resistor values for our design current.
The simulations we run include a DC simulation, a DC sweep sweeping two separate parameters, and a DC Sweep using a parameterized variable in our circuit. We show how a simulation can be a powerful tool for iterating on a design and to gain intuition for our real life circuit.
If you have ideas about other tutorials you would like to see us do please let us know in the comments.

Пікірлер: 21

@DaveGWIS 3 жыл бұрын

Really helpful and clear for the uber-novice like myself. The little stumbles made it very human too.

@eastofthegreenline3324 6 ай бұрын

This was really accessible and intuitive. Nice job!

@olegvelichko1659 3 жыл бұрын

That’s really neat! Going to use this tool from now on.

@abdullamasud4278 2 жыл бұрын

Thank you so much for the explanation through it all!

@mkepler5861 Жыл бұрын

SUPER INCREDIBLE!!!!!!!!!!!!!!!!!! THANK YOU AWESOME CIRCUIT SIMULATOR!!!!!!!!!!!!!!!!! mike huge thumbs up and a sub from me!!!

@sstrama Жыл бұрын

Excellent software simulator.

@museslide 6 ай бұрын

im sorry for repost this video in my channel for my homework🙏

@juliuszuben9560 3 жыл бұрын

love your work

@CircuitLabInc 3 жыл бұрын

Thank you! Cheers!

@cyrilmechkov3119 Жыл бұрын

An impressive movie... I have only one remark: The voltage across Re does not follow the input voltage simply because the base-emitter voltage is nearly constant and transfers the input voltage to the emitter. This would be the case if the collector of the transistor was left unconnected. The voltage across Re is not created by the input voltage by passing the input current through Re but by the transistor that changes its collector current through Re to set the voltage across it (almost) equal to the input voltage. This is actually the principle of negative feedback.

@basmaal-ghali9174 3 жыл бұрын

thank you

@montaramike 6 ай бұрын

Love your tutorials and the sim, but wondered why the sim requires a ground for DC circuits.

@n9jcvyellow Жыл бұрын

Would this circut limit any load bearing circuit, rather than a LED, regardless of what total resistance the load circuit has? Meaning, i have a small circuit of chips, and I want to limit total current to 18ma, can I just take the LED out and replace with my small circuit?

@darklightining6412 3 жыл бұрын

would you do a tutorial about how to make a common emitter amplifier concerning the calculation of the voltage gain and the relation between the frequency and the input impedance, please ?

@greenwoodforest8972 Жыл бұрын

You can find that in the transistor's data book! :-)