7 votes

Is it possible to use CRT tubes for audio amplification?

Technically, a CRT could be used to perform amplification as it possesses the three things you need to do so: A cathode (in the form of an electron gun), a control grid (grids, actually) and an anode. ...
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  • 1,662
7 votes

Amplifier with selectable inversion?

simulate this circuit – Schematic created using CircuitLab The standard configuration that I have used in the past would require two op-amp stages. The first stage is (nominally) unity gain but ...
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  • 22.6k
7 votes
Accepted

Amplifier with selectable inversion?

The same arrangement as shown by @Dwayne Reid can be configured to achieve the gain of two in a single stage by adding a single resistor. R3 is changed to 20k (twice R2) to change the gain in ...
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4 votes

How can negative feedback reduce distortion if A*beta>>1?

You can model a feedback system with distortion by adding a distortion voltage to the output, done here via adder X3 which adds a "Disto" voltage. \$ A_{ol} \$ is the open loop gain. \$ \...
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  • 57.4k
3 votes

Amplifier with selectable inversion?

Not sure how I missed this (I swear I did search extensively for a match) but this question is basically the same and has a very nice answer: Methods for converting PWM to +/- 10v Signal
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3 votes

Amplifier with selectable inversion?

The simplest approaches that use common parts all use two op amps configured as needed and switching the output between them. To that end, you can: Use op-amps with a shutdown pin. Those are usually ...
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3 votes

Does an amplifier consume any power when nothing is connected? (GPD2846A built-in 2W amplifier)

"Does it consume any power": Yes. "Does it consume the 1-2 W it would with a speaker connected": No. It'll pull a tiny bit of power, though it's impossible to know how much without ...
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  • 19k
3 votes

Where can I find large thru-hole heatsinks like this?

You buy heat sink extruded stock and drill it on a drill press then tap the hole. Don't forget to mechanically brace such a large heatsink to the PCB in a way other than the component. That might ...
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  • 45.9k
3 votes
Accepted

LTspice-RIAA-simulation not working out

Your output "vinyl" mimics the gain plot of the preamplifier. You need to flip things around so "vinyl" has a lower output at low frequencies and a higher output at high ...
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  • 3,745
3 votes

Does anyone know why this diff amp isn't working?

With a differential amplifier you usually use a dual polarity power supply. For one using NPN transistors the 'tail' resistor or current source goes to a negative supply, the collector loads go to a ...
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  • 3,386
2 votes

How does the common emitter configuration offer higher output impedance?

My recommendation: In general, one should not blindly trust "a person" who tries to explain something in a video. Of course, it is correct that the "material" (ohmic effects?) ...
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  • 22.5k
2 votes

How can negative feedback reduce distortion if A*beta>>1?

Quote: "Doesn't the condition of stability state that A×beta should be less than 1 otherwise it will be unstable. Does that mean we will get reduced distortion but on unstable condition?" ...
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  • 22.5k
2 votes

How can negative feedback reduce distortion if A*beta>>1?

One reason why negative feedback is beneficial to an amplifier is because it reduces distortion by a factor equal to 1+Abeta. If there is no feedback (open loop) then beta is equal to 0, 1+betaA is ...
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  • 4,805
1 vote

How can negative feedback reduce distortion if A*beta>>1?

A main property of any system with negative feedback is that it copies the inverse behavior of the feedback network. Thus, if a (linear) voltage divider with transfer ratio K = R2/(R1 + R2) < 1 is ...
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1 vote

How can negative feedback reduce distortion if A*beta>>1?

A canonical block diagram of the classic negative control loop is this: - \$r\$ is the reference, \$y\$ is the output and \$e\$ is the error. We want to minimize the error (ideally to zero) at steady ...
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  • 2,886
1 vote

LTspice-RIAA-simulation not working out

I remember old vinyl pop-click, pop-click records. The same curve appears at https://sound-au.com/project06.htm .
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  • 2,149
1 vote

How to disable Bluetooth temporarily for line in to work in mini hifi amplifier TDA7492P?

How can I disable bluetooth temporarily for line in to work? It appears that you can't. Also this amp has no line in. Googling for 'tda7492p bluetooth amplifier board manual' shows that the 3.5 mm ...
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  • 2,540
1 vote
Accepted

Picking up ultrasonic signals on a hydrophone

What is the best solution to try? You should get the H2a-XLR hydrophone and run it with the Zoom U-22 interface. The Aquarian website explicitly states this is what you should be doing: on the H2a ...
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  • 2,363
1 vote

Picking up ultrasonic signals on a hydrophone

The data for both products is lacking! These products are meant to be used underwater. They will perform very poorly in air due to the acoustic impedance mismatch (air to transducer). The H2a ...
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  • 3,745
1 vote

How does the common emitter configuration offer higher output impedance?

Ic is a voltage-controlled(Vbe) current sink (Ic) with some Early Effect leakage resistance but otherwise high impedance output by design. An Ideal current sink is infinite but over the linear range ...
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1 vote

Where can I find large thru-hole heatsinks like this?

OPA541 can dissipate quite a lot of power, 125W according to the datasheet, and the heat sink on the picture is way too small to exploit the opamp's capabilities. In addition, the PCB itself is in the ...
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  • 57.4k
1 vote

Amplifier with selectable inversion?

The "standard" solution shown in Dwayne Reid's answer is in fact a virtuoso circuit invented with an ingenious imagination. But to be convinced of this we need to see the "philosophy&...
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1 vote

What would the output impedance of the circuit below be?

It depends on VB. If the lower transistor is kept in saturation, then if you add additional current at RZ, the the lower device (in saturation) sinks it ==> its VGS increases by deltaI/gm. This is ...
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  • 12.4k
1 vote

Non-linear amplifier

The output of amplifier, by inspection, will contain DC, 5 MHz and 10 MHz components (where 5 MHz is fundamental and 10 MHz is extra harmonic they are talking about). LPF is providing a 3 dB loss in ...
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1 vote

Common Source JFET Amplifier Gain

FOR THE IMPATIENT: Skip to Point 6, the formula. Just as with BJTs, we must account for the internal resistance of the JFET source. For the JFET, this resistance is 1/Gm (Gm in Siemens or mhos). (For ...
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