The amplifier tag has no wiki summary.
0
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1answer
25 views
Is feedback transfer function the same as the transfer function for the whole circuit?
I have a circuit very similar to the inverting band pass filter circuit here:
I was asked a question about the circuit's feedback transfer function. Is this the same as the transfer function for the ...
1
vote
2answers
76 views
How does this circuit attenuate high frequencies?
I understand that this circuit could be used as a treble control circuit with high frequency gain occuring when R3 is set so a=b (we'll call this k=0), and high frequency attenuation occuring when R3 ...
2
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2answers
102 views
Why can't a feedback network use a capacitor? [closed]
Possible Duplicate:
Basic Frequency Control Circuit
In the following schematic, why can't R4 be taken away and the feedback network pass output feedback through C2 and R2?
-1
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1answer
87 views
Types of amplifier - what is the difference?
What is the difference between an open loop amplifier and a voltage follower (unity gain buffer)?
5
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6answers
286 views
Why is feedback required in op-amp circuits?
I understand that, in order for an op-amp to function correctly, a DC feedback loop from the output to either the inverting or the non-inverting input (depending on the external circuitry) is ...
2
votes
4answers
149 views
Basic Frequency Control Circuit
How does R4 prevent the output voltage drifting towards one of the supply rails to the op amp? I understand that R4 has to have a high resistance but I do not know why?
Here is the schematic which is ...
0
votes
2answers
50 views
Amplifying strain gauges on an arduino
I have 4 standard mild steel foil strain gauges bonded to a steel bar in a wheatstone bridge arrangement. They are implemented into a circuit with the INA 125P amplifier. I only manage to use about a ...
2
votes
3answers
107 views
What is the definition and purpose of a pre-amplifier?
I find in many places mentions of pre-amplifiers being used to boost audio signals prior to feeding to a power amplifier.
Wikipedia's article on pre-amps gives some hints at their usage, but it ...
0
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3answers
109 views
Switch at output of operational amplifier
I'm currently designing an active filter which has to pass an analog signal between two cables (PLC). I'd however like to not let it pass in case the signal is already present (up to a certain ...
2
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2answers
76 views
How do I use a clipping Zener at the input of an Opamp inverting amplifier?
I have a \$ V_{in} \$ signal for which I cannot guaranty that it would have an upper limit. I want to clip this input signal to a limit (e.g.; 8.2V) with a circuit like above.
Is this circuit ...
-1
votes
1answer
130 views
How to amplify an electret microphone
I need to amplify an electret microphone for use with an Arduino Uno. I have a few capacitors and resistors and several transistors one of which is an N-channel.
Any ideas?
Can you please also provide ...
0
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3answers
61 views
Lower Voltage RF Amplifier for 400 MHz
I'm using this Mitsubishi RF amplifer in a portable device. The Mitsubishi amp operates well between 7V - 9V.
But I have to interface with a power source that gives 1.5V, and stepping 1.5V up to 7V ...
-1
votes
1answer
58 views
Amplifying PWM to solenoid
I am driving a solenoid with a DRV103 (a driver for inductive loads by TI), but I need to allow more current to flow to the solenoid than the DRV103 can output. Initially, I tried a simple common ...
0
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2answers
111 views
Good LCD for clean mounting in hobby project?
I'm refurbishing an old Kenwood amplifier--- removing the old faceplate and adding a board with a microcontroller, multiplexer IC, digital pot for volume control, IR receiver, etc.
I'm also ...
4
votes
1answer
155 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?
3
votes
1answer
88 views
LM386 amp circuit lag
I'm building a motorcycle intercom and am using the LM368 IC for my amp. My circuit works well (surprisingly, I'm new to this).
I've got a button which I use as a push to talk switch. This works for ...
1
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2answers
112 views
detecting low signal levels with a transistor
This question made me wonder. Say I want to drive a LED when a small level audio signal is present. I understand how to do this with an opamp, but how about a transistor. You'd have to bias it so that ...
1
vote
1answer
126 views
Simple and powerful audio amplifier around BA4558?
I have two BA4558 ICs from an old home stereo. I tested them with simple negative feedback circuit for each channel and with power supply of +/- 6V. The speakers I used are most likely with 8 ohm ...
0
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3answers
132 views
The need for a Comparator
Hello i have an op amp shown here:
If i connect a speaker to the output of it the audio signal is amplified.
So far so good. But if i connect an LED to the output of the amplifier it doesn't turn ...
2
votes
1answer
99 views
In Common Emitter Amplifier Circuit ,Emitter Capacitor effect
I was wondering about the Effect of Emitter Capacitor in Common Emitter Amplifier? It is Suggested that Putting the Bypass Capacitor the output voltage gain is increased but how? As we want more ...
1
vote
1answer
79 views
Impedance for Helmholtz Coil Connected to Audio Amplifier
I am trying to design a Helmholtz coil, that will have an impedance of about 2 ohms (the reason for this being that I am going to hook it up to a audio power amplifier, so to get the same wattage ...
3
votes
2answers
133 views
Can someone explain this tube amplifier circuit for me?
I have a tube radio that has really low output (I mean the sound is barely audible at full volume). Probably some capacitor in the LF amp failed. However, after I downloaded the schematic diagram, I ...
5
votes
2answers
102 views
Why would a Diff Amp require both inputs to have a DC path to GND to work?
I'm looking at using a NI PXI-6255 DAQ card and I noticed in the manual it says "Both inputs of the (diff amp) require a DC path to ground in order for the (diff amp) to work."
Is this a common ...
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1answer
68 views
How to electromagnetically amplify voice? [closed]
How can I electromagnetically amplify the sound vibrations from my vocal cords to directly affect my body?
1
vote
1answer
118 views
Combine left and right channel at speaker level
I recently started a project to build an inexpensive speaker/amplifier that is portable enough to take outside easily. I purchased a center-channel speaker from a thrift store for $6 and an amplifier ...
3
votes
3answers
270 views
Why doesn't my transistor audio amplifier work?
I'm a newbie to transistors. Could anyone explain why my set up doesn't work ? The transistor is a 2N2222 NPN BJT, and the microphone is just a standard earbud. The loudspeaker is just one I ripped ...
1
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2answers
143 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 ...
1
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0answers
148 views
DIY simple line out converter for “floating ground” car head unit?
On a 25W max power (10V p2p @ 4ohms) balanced (push-pull) high level output factory car audio head unit from which I need to feed a mono amplifier (for subwoofer) that only has an unbalanced line ...
0
votes
1answer
106 views
How do I get 15V from a 34V power supply?
I have an audio amplifier with a regulated power supply putting out around 34V DC. I would like to add a preamp which requires on 15V. How would I draw 15V from the main power supply?
3
votes
2answers
223 views
100W Low Pass Filter
Currently I have a 60W amplifier for the 400-500MHZ band with a 50Ω impedance. In order to prevent jamming other frequencies I will need a low pass filter to block any frequencies above 500MHZ. I just ...
2
votes
2answers
105 views
Is there an amplifier such that the gain is equal to the ratio of two potential differences?
I have been toying with some alternatives to transistors in building logic gates. I am particularly interested in the device I tried to summarize in the title of this post. The chip would have 8 pins:
...
1
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2answers
99 views
Flipping a signal
I've an input of two input lines, one being connected to ground and one carrying the signal (measured to ground). The output should be three lines with one being ground and the others measured in ...
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votes
1answer
132 views
How does transistor amplify current? [closed]
Possible Duplicate:
I don't care how a transistor works, how do I get one to work?
Basic questions about transistor amplification
I have heard transistors are used in many electronic ...
6
votes
5answers
330 views
Simple Audio amplifier Using Transistors
I would like to build a simple audio amplifier using transistors. I know their are IC design specifically for the task. But i want to use transistor so i can learn how to use them for amplification.
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2answers
230 views
1.8v GPIO controlling 5v 10mA solid state relay
I have a Crouzet 84 134 900 solid state relay that I need to control with a 1,8V GPIO output from a Gumstix Overo Summit expansion board. I've tried the circuit drawn up for me in this answer, however ...
0
votes
2answers
93 views
Is it possible to mod a class 2 bluetooth device to work as a class 1 device?
I have two Microcontrollers which communicate over a bluetooth link (serial link, like RN-42). So far so good. Unfortunately the device is listed as a class 2 device and I noticed that the distance is ...
12
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5answers
382 views
Noise reduction strategies in electrophysiology
When recording electrical signals from cells (in a dish or inside a living human or animal body), one major problem is to increase the signal to noise ratio.
These signals are usually in the 10uV ...
3
votes
2answers
179 views
Capacitor in parallel with resistor on xoscope amplifier schematic
Short version: Why is C3 necessary in this circuit?
Explanation:
The schematic for the input buffer/amplifier circuit for xoscope is made up of subsections that are mostly broken down in the ...
1
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3answers
126 views
Question about the output voltage of an op-amp. (ua741)
When i hook up my opamp to a 9 volt battery (like in the image below), i get 8 volts from the output pin.
It gives the same reading when i attach both the inverting and non-inverting pins to the 9 ...
1
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2answers
150 views
Noise when powering headphones amplifier through USB port
This question is actually connected with this one:
Getting 1.2V from USB
I've successfully connected my FIIO E3 headphones amplifier to USB (so that I don't have to use batteries). But I've notices ...
1
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1answer
170 views
What type of amplifier do I need for this project?
I'm trying to make a custom PA system for my car, but I am confused about what type of amplifier I might need, or do I need one at all?
I'm wanting to take the main sound unit out of a "personal ...
1
vote
1answer
88 views
Adding microphone/amplifier to Gumstix Overo Earth COM?
I am new to hardware hacking in general. I have a Gumsitx Overo Earth COM and a Palo35 expansion board with audio in/audio out capabilities. According to Gumstix's wikipage on audio input, the ...
6
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2answers
274 views
What's a reference text on analog design?
I'm looking for a intermediate text that covers (discrete) amplifier circuit theory using BJTs and FETs and circuit elements such as current mirrors, differential stages, feedback theory, etc. My ...
3
votes
1answer
142 views
How to measure battery voltage
I am building a battery powered device. Almost all of my logic is running at 3.3v, although I do have a 5v supply for a few hobby servos.
I want to measure the battery voltage, but I can't do so ...
1
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2answers
99 views
mute de-amplify sound volume
I want to de-amplify the sound volume of my television.
My native language is not english, and I do not know the correct word, if any, for the opposite of amplify.
When my TV is turned from volume ...
0
votes
2answers
115 views
How can I attenuate any signal to 5V peak-peak?
How can I attenuate any signal to 5V peak to peak?
I tried the following design :
While I limited the output to 5V peak-peak, the circuit clipped the output to 5V instead of attenuating it.
My ...
1
vote
2answers
87 views
3.5DB splitter loss in voltage?
I am trying to figure out the loss from a cable splitter. I am assuming it is analyzing any other filter circuit. This should equals a loss by a factor of 1.5 or is there some special nomenclature for ...
2
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2answers
170 views
npn transistor base current question
Hi i am new to using transistors for signal amplification.
Can someone explain to me how to figure out the amount of current being drawn into the base of the transistor when it is in the common ...
2
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2answers
128 views
Circuit to exaggerate differences in current
Basically what I am after is some sort of a circuit which will amplify higher voltage signals, but possibly dampen lower voltage signals, in order to make a wider seperation between high a low ...
3
votes
1answer
111 views
Circuit diagram and components for Comfortron controller (Chevy, Oldsmobile, …)
I am trying to help repair a Comfortron heating and cooling controller for a late 1960's Chevrolet Impala. The Comfortron is an early climate control system that uses a combined vacuum and electrical ...
