New answers tagged amplifier
0
votes
Output level of common-source amplifier with PMOS load
Stating why the open loop circuit does not have a well defined bias voltage at the output in my own way: the open loop circuit has a poorly defined output voltage because the output impedance is very ...
- 1,379
0
votes
What is the purpose of this audio transformer in the circuit?
Main purpose is to act as isolation between a bridge-driven output intended for driving a speaker, but actually passing the isolated signal safely to your sound card. It really does no significant ...
- 165k
3
votes
What is the purpose of this audio transformer in the circuit?
This only answers Q1.
There are a couple of possible reasons for the transformer.
It eliminates ground loops which can cause interference due to current running through the car's chassis, etc., and ...
- 178k
1
vote
What is the purpose of this audio transformer in the circuit?
What is the main purpose of this audio transformer in this circuit?
To provide galvanic isolation between earth/ground on the left side amplifier and earth/ground on the soundcard. This means it will ...
- 467k
1
vote
What is a DC path in the feedback of an amplifier?
I have created a "schematic comic" to illustrate my answer. I can provide more details if needed.
No DC path
simulate this circuit – Schematic created using CircuitLab
DC path ...
- 18.2k
4
votes
Accepted
What is a DC path in the feedback of an amplifier?
You have two feedback paths, and they both look like R1 and C1 here:
simulate this circuit – Schematic created using CircuitLab
Potential fluctuations (AC) at OUT will be transmitted just fine ...
- 42.3k
2
votes
How can I down mix stereo to mono audio on a DFPlayer Pro?
While the question asks for how to modify the circuit, as an alternative if you control which MP3 files are used by the player the MP3 files could be converted from stereo to mono before being copied ...
- 6,153
2
votes
What is a DC path in the feedback of an amplifier?
The output cannot set the DC voltage of the inverting input. Because of capacitors blocking the DC. The output cannot work to do any feedback.
So no matter what input voltage there is, e.g. +1V DC, ...
- 165k
1
vote
What is a DC path in the feedback of an amplifier?
It means there is no DC path between the input and output. Lose C1 or C2, and you will have a DC path. You blocked it with C1 and C2.
- 994
1
vote
What is a DC path in the feedback of an amplifier?
Capacitors = AC
Resistors and indcutors have a DC component to them:
Source: https://www.animations.physics.unsw.edu.au/jw/AC.html
Feedback means output to to input, there is no way for a DC signal (...
- 87.2k
3
votes
Accepted
How can I down mix stereo to mono audio on a DFPlayer Pro?
You need to sum left and right into mono before the amp and use only one channel of the amp. Use resistors like you suggested in your question to sum left and right together. It's the most cheapest ...
- 165k
0
votes
NPN transistor base doesn't drain as much current as I calculated
Why does collector resistance \$R_C\$ affect base current? The answer is it doesn't, at least not much. You've just got something wrong somewhere. There's always a slight dependence of anything on ...
- 42.3k
1
vote
Accepted
Using a Y switch at amplifier output
How much power are you looking to switch? 100W? You can easily do this with a STDP relay per channel, or a DPDT to switch both channels at once. You do not need to worry about the crossover ...
- 8,231
0
votes
NPN transistor base doesn't drain as much current as I calculated
Ignoring odd arrangements, there are two cases that have very different results with BJTs: (1) operated as an amplifier (active mode); and, (2) operated as a switch (saturated mode).
Technically, ...
- 12k
0
votes
Best Technique to Find 'The' BJT For Your Circuit?
Made with microcap v12
Note that UJC1210K is discontinued, it can be replaced with some equivalent.
With the use of SiC MOSFET, you can try something like this circuit.
The dissipated power is "...
- 15k
0
votes
NPN transistor base doesn't drain as much current as I calculated
Choosing a base current depends what the load is and what frequency the load is driven, another words how much time is allowable the Bjt stays in linear region during switching. A higher base current -...
- 2,340
0
votes
NPN transistor base doesn't drain as much current as I calculated
The Vbe of the transistor will be about 0.7V so you can expect the base current to be roughly (5V-0.7V)/470Ω = 9.1mA. Since the base current is relatively high Vbe might be higher, and therefore the ...
1
vote
How to drive single or multiple pvdf film type piezo actuators
While the DC current required for a piezoelectric transducer is low, the AC current can be quite large. A PVDF element can be pretty well modeled by a capacitor so you can calculate the required ...
- 1,116
0
votes
Best Technique to Find 'The' BJT For Your Circuit?
You can try search & sorting tools on manufaturers sites also like On-semi. In your case I would filter according Ft parameter. Since the amp works in linear area the Ft/2 frequency is ussually ...
- 2,340
0
votes
caseecade op-amp
The circuit as stated does not work.
Made with microcap v12.
You should change to this circuit.
The frequency can be changed by adjusting R2 or/and R1.
Note that changes must be "small".
- 15k
2
votes
Accepted
IRF540 MOSFET overheating when used with IRS2104 driver as class D amplifier
Get rid or significantly reduce the 2.5 μF capacitor. It will draw massive levels of near-instantaneous current on each switching cycle. A pi-filter is a bad idea under these circumstances.
It all ...
- 467k
0
votes
Attenuating mid-supply biased audio signal before AC coupled audio amplifier
To answer your question : yes there is.
First, if there is significant DC on the volume, when you change the volume quickly, the DC component will also change quickly and this can be enough to produce ...
- 7,578
0
votes
Crystal oscillator based on a differential pair of npn transistors does not oscillate
You're loading the output with Q3. Remove Q3 and the parts it connects to. Start simple. No point in adding the load if the oscillator won't oscillate without the load.
The ...
2
votes
Crystal oscillator based on a differential pair of npn transistors does not oscillate
The basic idea will be something like this:
simulate this circuit – Schematic created using CircuitLab
It's not a complete design and I used \$5\:\text{V}\$ here. (I'd recommend keeping the \$...
- 12k
4
votes
Crystal oscillator based on a differential pair of npn transistors does not oscillate
You appear to be missing a connection at the collector of Q2. The wires cross but there’s no connection dot. Without this connection there’s no feedback through the crystal.
Also there is no voltage ...
- 26.1k
1
vote
Accepted
TDA2050 produces pulse on startup
Your TDA2050 is an opamp, operated in single supply mode acc. to your schematic.
And you use (as Aaron mentionned) R17, R18 (and C14) to create an artifical ground at 12V away from positive and ...
- 338
2
votes
Accepted
Can a low power rated Class D Amplifier drive a Speaker with higher power
You actually have the opposite problem: your amplifier L/R channel is 50W each, while your L/R speakers are rated at only 40W each. Meanwhile, you have 100W sub, and your speaker is rated 200W. So ...
- 56k
0
votes
How does this amplifier stage work?
Q1 is functioning as an emitter follower, but most of the current is supplied by Q2. R3 along with R5 and RV1 form a voltage divider that sets the overall gain. You can think of it as a very simple ...
- 177k
0
votes
I am driving a LT3092 current source with a variable voltage - to get a variable DC current, but the output needs to float 0 to 1.5V above ground
Since the LT3092 IC is basically just being used as a current driver in my first circuit, you can eliminate that expensive IC as shown below, which is a basically the same constant-current circuit, ...
- 429
1
vote
I am driving a LT3092 current source with a variable voltage - to get a variable DC current, but the output needs to float 0 to 1.5V above ground
Below is the LTspice sim of the LT3092 whose constant-current is determined by the control voltage into a single op amp.
The op amp is configured in a differential configuration that generates a ...
- 429
0
votes
Accepted
Given an active filter or any sort of operational amplifier with finite open loop gain, is feedback factor accounted for in the standard gain formula?
A first-order high-pass transfer function in s-space may be expressed in either one of the following forms:
$$\begin{align*}H_s&=A\cdot\frac{s}{s+\omega_{_0}}\\\\&=A\cdot\frac{\frac{s}{\omega_{...
- 12k
0
votes
Accepted
Understanding GBP, closed loop gain and open loop gain
Since you are given an open loop gain, but not a gain-bandwidth product it's likely that you are supposed to assume that the opamp has infinite bandwidth (what else can you do?). By the way, your ...
- 4,361
2
votes
Accepted
Using IRS2104 gate driver to drive BJT push pull stage
VS - VB is limited to 25V absolute maximum, so HO will not go from 100V to 0 (at least not more than once).
HO also has the wrong phase to drive a PNP transistor.
Even if it did work (perhaps with ...
1
vote
Symmetric square wave duty cycle reduces with increase in frequency in push pull stage
Try this circuit. It can easily drive close to 100mA into the load with only small duty cycle degradation at shown pulse drive frequency of around 100kHz.
- 57.6k
2
votes
Accepted
Symmetric square wave duty cycle reduces with increase in frequency in push pull stage
The duty cycle changing is explained by the asymmetric first stage. It just is not visible at low frequencies.
You have strong fast transistor that pulls signal down hard and fast with large sinking ...
- 165k
Top 50 recent answers are included