Tagged Questions
2
votes
1answer
63 views
BJT Amplifier I/P O/P
In a CB Amplifier, base is common to both I/P and O/P. Why is I/P applied at Collector and Output at Emitter?
Could it have been the opposite?
Similarly for CC and CE amplifiers why the chosen I/P and ...
3
votes
3answers
172 views
BJT Bias Design and Operating
I'm to the task to design a BJT Common-Emitter Amplifier with resistance at the emitter as in the figure, and for that I need to:
get the values for \$R_{1}\$, \$R_{2}\$, \$R_{C}\$ and \$R_{E}\$
...
0
votes
3answers
175 views
Input impedance is higher in Common-Emitter than Common-Base?
Why is input impedance is higher in Common-Emitter configuration as compared to Common-Base configuration as signal is applied on Base-Emitter junction in both Amplifiers. Not in both configurations ...
3
votes
2answers
247 views
Input and Output Impedance of a BJT
Hi I'm new to electronics and I would like to know how to measure experimentally the input and output resistance of the following common emitter configuration. I have access to a voltmeter, signal ...
0
votes
1answer
160 views
Emitter Resistance in BJT Amplifier
What is the importance of resistance at emitter and collector of BJT amplifier? What will be effect on output if they are removed?
-1
votes
1answer
211 views
Design rules for power AB amplifier stage [closed]
could you please point me to a good guide for a simple class AB power amplifier design based on BJTs (referring to the "classic" schema with complementary push pull, diodes to remove cross over, ...
1
vote
6answers
1k views
Speaker BJT amplifier function
I'm trying to understand the below circuit:
I have to analyze an amplifier circuit from a microphone to a speaker and don't understand how it works. I know that the first stage is a voltage ...
-1
votes
1answer
183 views
BJT Amplifier Design [closed]
I am struck between the right method of biasing for BJT.I want to design a BJT power amplifier, i need maximum current at the output because of the low impedance of the load as well as adequate ...
0
votes
1answer
135 views
Exam question: measure amplifier \$h_{oe}\$ using a signal generator and oscilloscope
I'm running through some old exam papers at the moment and one of the questions are:
The parameter \$h_{oe}\$ is needed to calculate the output impedance of an amplifier. Explain in detail how to ...
6
votes
1answer
213 views
What's the difference between small signal bipolar junction transistors (BJTs) marketed as switches vs. amplifiers?
For instance, the MMBT3904 and MMBT3906 BJTs are listed as NPN/PNP Switching Transistors, and the datasheets mention the switching times, while the BC846 and BC856 BJTs are listed as NPN/PNP general ...
3
votes
3answers
405 views
Do two stage common emitter current amplifiers add or multiply?
So I've seen alot of explanations on two stage voltage amplifiers and how how their gains can be multiplied together. My question is when you are using a two stage common emitter amplifier for current ...
5
votes
1answer
1k views
BJT in Reverse Active Mode of Operation
What will happen if for a BJT transistor it's Emitter terminal is treated as collector and collector as Emitter in a common Emitter amplifier circuit?
1
vote
2answers
284 views
Short circuit protection in simple audio current amplifier
In my class, we are to design a current amplifier with short circuit protection.
In our design, we utilized 2 emitter follower amplifiers (Q3, and Q1).
We then added Q4 and Q7 to lighten the current ...
13
votes
3answers
2k views
I don't quite understand this FET-BJT preamp circuit
I see this circuit a lot on electret microphone preamps, but I don't quite understand it. The FET is operated as a common source amplifier, so it has gain, inverts, and has relatively high output ...
