An amplifier can be used to adapt the range of the signal to a requirement, to make it more robust for transmission, or to satisfy interface requirement (like input/output impedance)
1
vote
2answers
67 views
How does this circuit multiplex an antenna between a transmitter and receiver?
I've built a Softrock RXTX kit (full schematic: pdf gif, see lower-left corner). It has one connector for one antenna used for both receive and transmit, but I don't fully understand (likely due to my ...
2
votes
1answer
84 views
Analysis of Shunt Circuit
I am having trouble computing the closed loop gain of the circuit below:
It seems clear that this configuration is a Shunt Voltage but I just can't figure a way of computing the feedback factor and ...
3
votes
1answer
69 views
Are chopper amplifiers same as chopper stabilized Amplifiers?
I was wondering if the chopper amplifiers are same as chopper stabilized amplifiers. If no, can you explain what is the difference?
0
votes
1answer
44 views
Powering several amplifiers with one power supply
I need to power 5 industrial amplifiers for a project but I am not sure I can use one power supply for all. Here is the amplifier model I will use:
http://www.hbm.com.pl/pdf/a0114.pdf
And manual says ...
1
vote
0answers
48 views
How does zero balancing work in an amplifier? [closed]
I'm using an industrial amplifier which has coarse and fine balancing. I uploaded the circuit picture and circled the fine balancing in red. I use it to zero the output(for offset). It is done by ...
0
votes
2answers
83 views
Reducing noise in an audio amplifer using opamp
I am trying to make an audio amplfier using an opamp for a project. It works kind of okay but the only issue is there seems to be a lot of noise in the output of a 0.5 watt speaker. I have tried ...
1
vote
0answers
51 views
Tuned Amplifiers
I'm trying to fully understand some tuned amplifier circuits and i guess this should be really simple to you guys.Here are them:
I would like ask you three things things, each one regarded to ...
-6
votes
0answers
109 views
Coupling a current generator to a very high impedance [closed]
I hacked my renault stock car radio, cause I've lost code. So I decided to enjoy the TDA7560 as a final stage. Actually I made an hack you can see here
It works well, but I have a few doubts. I ...
0
votes
1answer
75 views
Planning an amplifier using a transistor
I want to plan design an amplifier of tension voltage using a transistor:
but I don't know how I can choose the values of \$R_1\$, \$R_2\$, \$R_3\$, \$R_4\$, \$C_1\$ and \$C_2\$..
I want to obtain ...
4
votes
1answer
76 views
Least noisy pre-amplifier design
I am building a frequency generator circuit and need some advice. I am using the AD9833 DDS generator (programmed from a PIC16F876) to generate frequencies and I wish to be able to adjust the gain.
...
4
votes
2answers
116 views
subtract two AC voltages with instrumentation amps
I'm implementing the so-called "3 omega technique", where a thin metal line is excited with a sine current. The metal has a high TCR which causes a 3rd harmonic oscillation, and I need to measure the ...
3
votes
1answer
81 views
Strange behavior from variable-gain amplifier
Sorry, this might not go anywhere. My first SE question, though, on any site.
I've built at least three distinct audio amplifiers with the TDA7056B, which is a really great amp. It takes a voltage ...
1
vote
1answer
82 views
simple pre-amp for ELF antenna?
I'm looking to build an antenna to research the 5-500 Hz range. I already had decent success with just a simple square loop 1.5 ft per side (air core), about 12 turns. Despite having an estimated ...
9
votes
4answers
443 views
Why is it desirable in an amplifier to have high input impedance and low output impedance?
I've learned that it's desirable in an ideal amplifier to have high input impedance and low output impedance. Why exactly? What are the implications an amplifier has the opposite- low input impedance ...
3
votes
1answer
106 views
What can the source of 100Hz noise be?
I'm making data acquisition with an amplifier (amplifier is amplifying a transducer and is connected to a data acquisition hardware).
After I make data aq. I am plotting the output signal data in ...
2
votes
1answer
53 views
Electret microphone with class a amplifier has no speaker output
I' m a relative beginner trying to build this audio amplifier, using this electret microphone, and output my sound to this 8 ohm speaker.
I'm getting no audible output.
I tested the microphone ...
3
votes
1answer
152 views
BJT Differential Amplifier-Long Tailed Pair
I am trying to solve this assignment
Consider this schematic (the BJT's are in the effective area, with
\$\beta=200\$ so as to \$i_e\approx i_c\$). Also \$R_1>>R_E+r_e\$.
Define ...
1
vote
2answers
103 views
Circuit analysis of mono audio preamp (K1803 Velleman)
For a school project I have a question about the first part of the circuit below (amplifies at 20*log(220k/2.2k)=40dB). I know that U2A is the amplifying part of the circuit. The problem is U1A and ...
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 ...
1
vote
2answers
67 views
Total Harmonic Distortion
If a specific project specification says "...amplifier must be linear such that the harmonic distortions are maintained below -40dB...", does that mean that a THD of -30dB would meet the requirements ...
-2
votes
0answers
37 views
Why would a 3G repeater stop working? [closed]
I recently purchased a 3G repeater identical to this one, for my dad's boss who moved into an area with horrible connectivity (both mobile and wired). The first few months the signal went from 1 or 2 ...
4
votes
2answers
160 views
3.3V DAC output to 50V amplification
I have DAC 3.3V generated narrow square pulses that I need to amplify to 50Vdc. For this purpose an OPA551 single supply opamp works fine, but it's quiescent current of ~7mA @ 50V consumes too much ...
0
votes
3answers
135 views
what is meaning of infinite bandwidth of an amplifier
I have just learned about amplifier but the term infinite bandwidth confuses me a lot.plesse explain with some example.
-1
votes
1answer
99 views
Calculate output of Transistor Common Emitter Amplifier
I have a waveform selector circuit shown above. The input signal is a 1 kHz alternating Square wave with a pk-pk value of 8.5V (above the x-axis).
The output waveforms in order starting from the ...
-6
votes
2answers
126 views
Simple amplifier Cuircuit [closed]
I am new in electrical transistors. My project is to make a 1 watt audio amplifier. Can anyone provide a best amplifier circuit using darlington pair and 2N3904 transistor. i searched google. So ...
2
votes
1answer
157 views
2N3904 Darlington Pair
I am making a amplifier with darlington Pair with 2N3904. In input i used my mobile phone & additional supply of 5 volt. It simulates well in Multisim11 BUT in real the second transistor gets so ...
0
votes
2answers
91 views
Darlington Emitter-follower used as a buffer
I have a circuit with a Darlington emitter follower used as a buffer between a common emitter amplifier and a low resistance load (speaker). i wanted to know if this arrangement could alone (with the ...
-1
votes
0answers
53 views
Amplifier for 40kHz ultrasound signal [closed]
I need a simple amplifier for a 40kHz ultrasound signal. I found this (source):
How do I calculate the values of the components?
2
votes
1answer
104 views
Guitar amplifier
I want to build my own guitar amp and I know a little about electronics (handling op-amps and little more) and I would appreciate if anybody could explain me these circuits,
...
2
votes
2answers
62 views
Why is the following simulation not working?
The following is a multistage amplifier. It consists of 3 parts:
Waveform generator and inverting amplifier
A small signal amplifier with gain 20 and a small signal amplifier with gain 10
A power ...
10
votes
6answers
332 views
Amp measures board twist (unfortunately!)
Well, this is a toughie -- though fairly simple. Does anyone have experience with board twist affecting your circuit?
We have a board design that is supposed to measure a loadcell. We have finally ...
1
vote
1answer
102 views
Circuit to drive a speaker
I am looking for a circuit to drive a speaker to make a fairly loud simple tone - a square wave driven from a microcontroller (Arduino/ATMega).
There are obviously a billion chips and amplifiers out ...
2
votes
2answers
78 views
How to improve nasty form clipping behavior in differential input stage
The amplifier in the following schematic, when simulated, shows that it can cleanly amplify a signal with 0.1V amplitude to 10V. When driven with a larger signal, though, the behavior is very nasty in ...
4
votes
2answers
81 views
Single Pole Amplifier
My text book says, "Single Pole amplifiers are always stable,hardly surprising, because in the worst case it can never go beyond 90 degrees."
But it did surprise me and I cannot figure out why a ...
0
votes
0answers
45 views
Amplifier circuit - NMOS mode of operation? Gain?
Ok I have the following circuit, with values of variables:
\$\displaystyle R_{1} = 1 M\Omega, R_{2}=10k\Omega,~~ k_{n}C_{ox}\frac{W}{L}=1mA/V^2\$ , and \$V_{T}=1V\$.
1) When \$v_{IN}=0\$, calculate ...
2
votes
3answers
118 views
Difficulty with Common Emitter Amplifier
I'm trying to take the input from a microphone and use it to power an LED, so that it's off at ambient sound, and (the peak brightness) gets brighter with noise level. It's okay if it flickers, I'm ...
1
vote
1answer
136 views
How to amplify 3.3 volts to 8-9v?
I'm a total newbe in electronics but I like to make things up. All I want is to turn on a "black box" of leds (that operates at 8-9v) when my motion sensor is activated. The problem I've got is that ...
2
votes
1answer
183 views
Best way to go about biasing a Class B audio amplifier?
I am trying to bias the class be audio amplifier in the provided pdf. None of the resistor values are correct so the bjts are unbiased. What is the best way to go about starting to bias this?
...
1
vote
1answer
97 views
Output Resistance Voltage Controlled current source
I am having problems evaluating the output impedance (\$R_{out}\$) of a voltage controlled volage source, the notes I am using say the output impedance is
$$ R_{out} = \frac{r_o}{1 +AK} $$
but I ...
1
vote
2answers
98 views
Tips for adding voltage op amp to equipment
I have a source that creates a smooth sine wave in the range ±100mV at 1-15Hz.
Due to distances I need to amplify the signal to at least ±5V, and I should also maintain the shape of the signal if ...
3
votes
2answers
134 views
What's wrong with this Phase Shift Oscillator?
I am trying to design a phase shift oscillator, using a CE Amplifier.
I have a Vc of approximately 6V, gain of approximately 40(>29, as required).
I aim for an oscillation frequency of 1.5 kHz.
But ...
0
votes
1answer
121 views
How to calculate the resistors and capacitors for an amplifier circuit [duplicate]
Here is an amplifier circuit that I was given in a previous question:
They told me to use this for an experiment for using magnetic fields for nearby communication instead of radio frequency. Here ...
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}\$
...
5
votes
1answer
120 views
What is loading effect?
I have come across this term many times while studying amplifiers. How does this effect affect an amplifier circuit(or any other circuit in which it plays a role) and why is the input impedance kept ...
0
votes
0answers
105 views
2.1 sound system noise
I have a 2.1 small sound system that makes a high frequency noise when turned on, whether the input is grounded or not. I've opened it and measured the frequency of that noise with a scope and it is ...
0
votes
3answers
176 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
249 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 ...
4
votes
3answers
148 views
For what reason(s) is it not desirable to have the amplifier gain depend on the β of the transistor.
For what reason(s) is it not desirable to have the amplifier gain depend on the β of the transistor.
4
votes
3answers
250 views
simple audio amplifier
I did this circuit in my protoboard, and it worked for a while, but the quality sound was terrible, and suddenly it stoped working. Can anyone explain me in which part of the circuit i did something ...
0
votes
1answer
238 views
Amplifying Low DC Voltage Consistantly
I'm looking to build an amplifier circuit to amplify a small DC voltage signal (between 0-15mV) to the range of 0-1.3V. I tried messing around with a standard non-inverting op-amp amplifier circuit ...
