Linked Questions

2
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3answers
2k views

Terminology for BJT “regions of operation”

How regions (modes) of operation are defined and correctly named? The most controversial thing is the so named “saturated region/mode”. It is defined differently, sometimes radically different, in ...
3
votes
3answers
10k views

Determine saturation base current from NPN transistor datasheet (or what resistor do I need to ensure saturation?)

The Fairchild 2N3904 has a long data sheet so let's use that for this exercise. I'm interested in using an NPN in common emitter configuration --- it's for switching. It's my understanding that an ...
3
votes
1answer
8k views

Shortcircuit protection with PNP

R1 became RS R2 bacame R 1)Is this a correct shortcircuit protection? 2)What is the max current that can flow before the transistor enters in saturation?
2
votes
3answers
5k views

Why is saturation region called so in BJT characteristics?

I understand base-collector (current) linear relationship is lost in saturation region and collector current will be lesser than \$ \beta * Ib \$ . Hence,at max, we can call such a region as non-...
-1
votes
1answer
6k views

BC5478 transistor: as the base voltage increases, the collector voltage decreases [closed]

BC5478 (or BC547B) transistor: VBB = 22mV, 0.03mA RE = 220ohms, there is an LED after the RE resistor. As shown there is no current to the collector pin. The readings I get: collector shows 296mA ...
2
votes
2answers
2k views

Concept of “resistance” and “power dissipation” in a transistor - Explanation?

Ok, so I've got way more experience with mosfets than BJTs. I'd become very accustomed to the idea of mosfets having a specific 'on' resistance, which would allow me to calculate actual heat ...
0
votes
2answers
1k views

in saturation of BJT, the current gain is reduced

I studied in sedra and smith 'microelectronic circuits' that in saturation, beta gets changed and becomes less than the original beta (which is constant for a transistor). How is it possible? Because ...
0
votes
3answers
614 views

How can we prove that collector current in active region is higher than the saturation region?

In the VI characteristics of BJT transistor its showing that the collector current in saturation region is less than the collector current in active region. How can we prove it with a BJT circuit?
1
vote
2answers
1k views

Why Beta value is changing and very low in this circuit

I am simulating a circuit in Proteus 8.1 and I am getting very low value of Beta (16 in this case). It is changing depending on the resistances. Can you please guide what is happening here? d
3
votes
1answer
971 views

NPN transistor circuit connection, what determines which region it is at?

I know that for an NPN transistor to be in the active region, the base emitter should be forward biased and the base collector should be reverse biased while for the NPN transistor to be in the ...
3
votes
2answers
322 views

Why does a BJT enter saturation?

I'm a beginner in EE, learning about the forward active mode of transistors. The equation, Ic = Ib * BETA, and Ic=Ie * ALHPA, are referred to as the ways to figure out what base resistor you should ...
0
votes
2answers
522 views

Current gain characteristics versus Collector Emitter voltage. Where is the transistor saturated? Can a transistor be saturated with a VCE of -10V?

I'm fairly new to transistor usage and determining stages of operation for a BJT. However, from what I've learned, in order for a BJT to be saturated, both junctions need to be forward biased, and ...
2
votes
1answer
301 views

Voltage divider bias (BJT) leads to a huge voltage drop across the collector resistor. Why?

I've already looked for similiar questions, but couldn't find any. Basically, I'm new in electronic circuits analysis and, after following my professor's lecture and looking on the internet I found ...
4
votes
2answers
225 views

What happens when a BJT doesn't draw enough \$I_c\$ to be properly biased?

I have a basic circuit, that looks like it's an except from the Electronics 101 textbook if you smudged out some of the numbers on the diagram out: simulate this circuit – Schematic created ...
1
vote
1answer
41 views

Charasteristic curves for a transistor working in a common emitter configuration

Configuration According to my text book, When we use a transistor as an amplifier, there generally 2 resistors, one is input resister(R in) and the other is output resister(R out). Normally ...