BJT - Base Biased Circuits

A description of what biasing is as well as a description of how to bias a transistor circuit using a voltage source and resistor at the base of a BJT. This kind of biasing is very simple to do and analyze but the actual biasing point is heavily dependent on the beta value of the transistor and also requires two power supplies.

[@montezeminor2854]

I'snt that just the voltage just at the collector and not Vce. The voltage drop across the collector resistor is 8.6v then subtracted from the source is 6.4v. What about the 0.7 volts from the emitter.

[@petergrierson3898]

Excellent tutorial. Explained very well and helped fill in the gaps from my work book. Thanks for your effort David. Very much appreciated.

[@TheMichaeljohnny]

then no current will be flowing through the wire??

[@KazKylheku]

Base bias does not have to use two different power supplies. In this example circuit, you could just use the 15V supply, and use a larger valued base resistor to keep the base current the same as what it would be under 5V.

[@VoidHalo]

What advantage has this method got over using a resistor voltage divider connected to the 15v supply to provide the appropriate base voltage and current? If any.

[@talideon]

None. It's just for introducing biasing in the simplest configuration possible.

[@KAFA2020]

Very interesting. Zaza-Kallah-Khyer

[@sammetal92]

Well, the emitter gives an amplified output in an NPN transistor. So if you had a circuit that you needed to amplify, I think you'd put the circuit in between the ground node and the emitter junction. I'm a student too though, I'm just saying what I understand :)

[@phetoleerrol511]

Can I get full lesson of transistors especially basics of electronic 1 please help me?

[@Curiousitydriven]

Plz make a video about how to choose gate resistor value(calculation) in case of MOSFET

[@matter9]

Thank you so much David Williams! I learned a lot! At BCIT for Robotics with Maurice LeNoble, Im glad you made these videos these were amazing study aids!

[@BigAL-x7f]

Hi Mr Williams, you do not maybe have a website or a means where students could ask one or two questions about these BJTs do you?

[@TheMichaeljohnny]

oh thanks,you may be wrong but your words gave me a little intuition.

[@jimedgar6789]

I watched this three times and finally REALLY understood the biasing process... so much so a light bulb appeared over my head and I LITERALLY laughed for about three minutes. Enlightenment comes in many form I see.

[@tupai62]

what the base resistor calculation formula for BD139 transistor?

[@talideon]

The formula is the same for all transistors of the same type. However, certain values might change and for those you should look up the datasheet.

[@TheMichaeljohnny]

but how can it work then when no current is flowing through the b-e circuit????

[@talideon]

Vbb creates a a potential difference across the base an emitter, so there would be current flowing. The circuit as presented is a bit useless though, because it's either going to be always on or always off in this configuration, as there's no signal line coming into the base. I think the lack of a signal is what might be confusing you.

[@exekuter1]

Si diode(simple PN junction) has a potential drop of 0.7V.

[@sammetal92]

grounded, meaning that the point is at 0 volts.

[@jayaramkrovvidi6080]

is it different from self bias?

[@TheMichaeljohnny]

with respect ground??????????????what does this means??

[@taylorstechtalks8456]

At ground, the voltage is 0, so when you’re calculating the collector-emitter voltage (Vce), you do so with respect to the 0V at ground

[@sammetal92]

Yeah, that's just how base bias circuits are made :)

[@Tyconus]

All videos I search explains base biasing, even though it's the worst and the most rarely used technique. I would have appreciated collector-base or at least classical voltage divider. You wouldn't want to bias your BJT this way in your circuit. So why discuss it?

[@talideon]

You start with this because it's easy. Other biasing techniques are more useful, but this one is good for introducing the concepts without getting bogged down in other subjects or maths. Other techniques are discussed in other videos on this channel.

[@lotus1219]

Thanks. It helps a lot! good preparation for final exam. =)

[@Justsquareenough]

Thank you. Great video.

[@killgil200]

wreszcie ktoś to dobrze wytłumaczył! Dzięki!

[@146fallon]

Thank you very much for saving me from misery. 😎💪👍

[@DoaRC15]

Thank you so much. You are so much better than my university lecturer!

[@mateuspinto5068]

Thank you ! Nice Video -- It helps me A lot !!! :)

[@sachinkotian944]

Awesome !!! Thanks David

[@mobeepo]

very clear lecture (even that i learned this 20 years ago)

[@nekhoulsalah4987]

Thank's David you saved my ass ;)

[@michaelcostello6991]

Awesome. Thank you. Really interesting.

[@muhammadusman75231]

thnk u sir.

[@dvoorganisation459]

Thank you Sir

[@blink3r_fluid]

In my first year of the ELEN program and these videos are clear, easy to understand, and concise. Thank you for helping students even a decade later!

[@layneheins2770]

meow

[@ElectronXLab]

Great to hear! I guess I'll see you IRL in September :-)