Constant Current Source

[@benthere8051]

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.

[@ovalwingnut]

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

[@craighollinger9972]

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.

[@ThanassisTsiodras]

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

[@cateyenebula]

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]

Glad I could help.

[@shvideo1]

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

[@craighollinger9972]

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

[@mokus8643]

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

[@craighollinger9972]

Thanks for watching.

[@M0NTVHomebrewing]

Thanks! Great explanation. Very helpful.

[@wasiuadeleke6869]

Thank you for your explanations

[@zainaabdin]

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

[@craighollinger9972]

Thanks for watching!

[@Yorumcu63]

Great video

[@dd0356]

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

[@craighollinger9972]

You are welcome. Thanks for watching!

[@ماياكلببنو]

Legend brother

[@carbonosilicio5318]

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.

[@mark8664]

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

[@konstantinosvafeiadis4548]

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]

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

[@ziadfawzi]

Thank you so much.

[@craighollinger9972]

You're welcome!

[@MrBobWareham]

could you use an NPN instead of PNP

[@craighollinger9972]

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]

Thanks for that

[@cancaonegro]

Same question as you! :D

[@christianurgese]

What does happen decreasing source voltage ?

[@craighollinger9972]

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.

[@gammersunity4117]

Why does it out 1.1v for me, diode is 1n4007

[@horacewonghy]

voltage regular + series resistor = constant current

[@deepakroy82]

i need ur help

[@hamaraapnaboutique5888]

hindi m do

[@labanchege5261]

Was the first four minutes really necessary it makes tge video boring

[@craighollinger9972]

When I find something boring in a video, I just use the slider and move ahead.