Constant Current Source

Рет қаралды 40,669

Craig Hollinger

8 жыл бұрын

In this video, I describe a constant current source used to drive the LED backlights of a LCD.

Пікірлер: 37

@ThanassisTsiodras 6 жыл бұрын

Thank you, Craig! Useful circuit to know about, and very nice and clear explanation of its inner workings.

@ovalwingnut 4 жыл бұрын

That was down right magical, as I try to wrap my head around "constant current". Thank you 👍😁

@craighollinger9972 4 жыл бұрын

The circuit is "constant" within limitations, as I showed in the video, but is useful otherwise. Keep studying basic electronics, you'll get it in time. Thanks for watching.

@shvideo1 3 жыл бұрын

What a great circuit and so well explained. Thank you also for the component part numbers in your circuit. Great work.

@craighollinger9972 3 жыл бұрын

I'm glad you found it useful. Thanks for watching!

@benthere8051 Жыл бұрын

Thanks, Craig. That's a very useful circuit. The two silicon diode voltage source is much better than a zener diode because the low voltage zeners are hard to source and only available in a limited number of voltages.

@cateyenebula 2 жыл бұрын

Just what I needed to drive my DC optocoupler with an AC input. I just need to add an additional diode and I'm set. Thank you for the excellent explanation and demonstration!

@craighollinger9972 2 жыл бұрын

Glad I could help.

@Yorumcu63 2 ай бұрын

Great video

@M0NTVHomebrewing 11 ай бұрын

Thanks! Great explanation. Very helpful.

@wasiuadeleke6869 Жыл бұрын

Thank you for your explanations

@user-vp9wi1nk5k Жыл бұрын

Legend brother

@zainaabdin 4 жыл бұрын

Thanks....Simple. explanatory. useful. practical

@craighollinger9972 4 жыл бұрын

Thanks for watching!

@dd0356 5 жыл бұрын

thank you very much. very clear video. greetings from india!

@craighollinger9972 5 жыл бұрын

You are welcome. Thanks for watching!

@mokus8643 7 жыл бұрын

nice clear job thanks...good teacher skills...cheers to you

@craighollinger9972 7 жыл бұрын

Thanks for watching.

@ziadfawzi 3 жыл бұрын

Thank you so much.

@craighollinger9972 3 жыл бұрын

You're welcome!

@konstantinosvafeiadis4548 3 жыл бұрын

Is it a good idea to put a trimmer (rheostat) of ~47ohm in series with the 68ohm resistor, in order to have a variable brightness on the backlight? Thank you very much for sharing your knowledge.

@craighollinger9972 3 жыл бұрын

That would work if you could find something that low in value.

@mark8664 4 жыл бұрын

I prefer using an NPN transistor. Those PNP's give me a headache :)

@christianurgese 5 ай бұрын

What does happen decreasing source voltage ?

@craighollinger9972 5 ай бұрын

The circuit is quite simple, so not perfect. The current will change slightly as the source voltage changes (up or down), but it's pretty constant. That's the whole point of the circuit, constant current.

@deepakroy82 7 жыл бұрын

i need ur help

@MrBobWareham 7 жыл бұрын

could you use an NPN instead of PNP

@craighollinger9972 7 жыл бұрын

Yes, you can. Basically just turn the circuit over but keep the diodes pointing toward ground. The device you want the constant current to flow through now gets connected between the positive rail and the collector of the NPN transistor.

@MrBobWareham 7 жыл бұрын

Thanks for that

@cancaonegro 5 жыл бұрын

Same question as you! :D

@horacewonghy 2 жыл бұрын

voltage regular + series resistor = constant current

@carbonosilicio5318 2 жыл бұрын

Good explanation, you have very nice and soft voice always constant and clear but, if i may sugest, use some sort of a soft matt on the table in order to avoid those clicks and pops of the hard objects while moving them. It would help alot for some of us with sensitive hearing. Thank you.