6 votes
Accepted

Why does the voltage not change when the resistance of the resistor changes?

The circuit is taking the battery negative as the 0 V reference. Many simulators would force you to add a ground (GND) symbol somewhere on the bottom line of your schematic to make this clear and so ...
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  • 160k
6 votes

In a DC voltage sensing circuit, what's the need for capacitors on input and output?

C22 may be useful if the DC input voltage contains an AC ripple or noise, that needs filtering. C23 at the OpAmp output is not a typical design. Many OpAmps can not drive such a capacitive load and ...
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  • 1,889
5 votes

Pull up and down resistors at the same time

The pull down value depends on your MCU and it reads in the data sheet. Open the data sheet and find the value. It might be tens of kilo-ohms. However it will likely change nothing. Pulling down ...
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  • 89.2k
4 votes

Why does the voltage not change when the resistance of the resistor changes?

You may consider wires to be 0Ω resistors, and the potential (voltage) at every point along them to be the same. So all wires connected together all have the same potential, and every point along ...
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  • 7,865
4 votes

12V on 24V PSU with Buck and Resistor

This is not very reliable. The MP2307 is rated at 23 V which is an unusual value and indicates there might be a problem operating above this. Your 24V supply will have a tolerance and could be 25 V. ...
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  • 13.9k
4 votes

Can I run resistor at a power higher than rated if I have external cooling?

It’s up to you to evaluate whether it’s okay. The manufacturer may not support you, since you are operating outside of the absolute maximums for the part. If you wanted to be on solid ground, then run ...
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4 votes

Can I run resistor at a power higher than rated if I have external cooling?

If you need a reliable design, no. Indeed you might not even get that, as the rating depends on ambient temperature and free airflow, and if those are in limited supply, you don't get the datasheet ...
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  • 2,413
3 votes
Accepted

Current limiter for VOD3120AB

What is the value of the Resistor that I must add to the VCC of the VOD3120AB so that the VOD3120AB works properly? You are thinking about this incorrectly. Just supply the device with 24 volts and ...
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  • 384k
3 votes
Accepted

finding replacement for resistor labeled as fuse in schematic

Pick a fusible "safety" resistor of the same value (3.3\$\Omega\$) and tolerance (5%), and a similar physical size. It looks like a metal oxide film type. There are also wirewound types. ...
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3 votes

Astable multivibrator small capacitor values

To expand on SP's answer: The reason the circuit did not work has nothing to do with you or the circuit; it's because of LTS. Simulators often have theoretically perfect resistors and capacitors, as ...
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  • 12.8k
3 votes

Astable multivibrator small capacitor values

Here is it working with 1nF capacitors. I did two things, first I modified one of the capacitors slightly but still well within the tolerance of likely real capacitors. You could change one of the ...
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3 votes

What does a pull-up or pull-down resistor actually "pull"

A mechanical analogy might help. Let's say we have a lever that is pressed to perform some action. When the lever is released we want it to return to a predefined state and definitely don't want it to ...
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  • 160k
2 votes

Can the connection of collector and base in these circuits be considered as a diode connected transistor?

The diode connected transistor requires a direct short circuit between collector and base, to be called a "diode connected transistor". That is, a 0Ω resistance, a wire, connects them. The ...
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  • 7,865
2 votes

Nichrome strip and resistor

The total resistance \$R_N\$ of 60cm of 2.3Ω/m nichrome strip is: $$ R_N = 0.6m \times 2.3\Omega = 1.4\Omega $$ When placed across 220V RMS, this will dissipate power: $$ P = \frac{V_N^2}{R_N} = \frac{...
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  • 7,865
2 votes

Blue/green SMD resistor

The existing answer is more than adequate, I am just adding some example series: VSMP: probably the aforementioned robin's egg blue, VPG precision TNPU: deep blue, very precision MC AT: deep blue, ...
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2 votes

What conditions can cause a PCB fuse to fail and act as a resistor?

Pulses with low duty factor will erode filament faster than the temperature rise thus non-fusing resistance and more inductive in nH so dI/dt also causes fatigue and reduction in wire diameter with ...
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2 votes

SPI MISO line not working

One classic mistake is that when you connect two live, supplied boards and the TTL level signals connect before ground pins, something else might become ground temporarily, resulting in wrong voltage ...
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  • 14k
2 votes
Accepted

Which electronic circuit simulator is working wrong?

Try looking at things in detail: -
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  • 384k
2 votes

Why does the voltage not change when the resistance of the resistor changes?

In simulations, voltage sources are ideal: the voltage across a source is exactly what you set the source to. So the voltage across the resistor is exactly 5V, and will stay that way no matter what ...
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2 votes

Why are there two NOT gates in a complementary PWM circuit?

The RC circuit will not produce a clean digital pulse. The edges will be rounded. Your drawing shows the rounded corners of the output of the RC circuit. The first NOT gate (actually a Schmitt ...
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  • 58.2k
2 votes

finding replacement for resistor labeled as fuse in schematic

It's labeled as F because it's a fusible resistor. The schematic gives the resistance as 3.5R I think due to the amount pixels missing.
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  • 71k
2 votes

In a DC voltage sensing circuit, what's the need for capacitors on input and output?

If the input signal is always DC, why do I need these capacitors? Alas, the input signal is usually not DC, because various source of interference superimpose their own AC currents on top of the DC ...
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2 votes
Accepted

How to infer resistor size from the manual of this microcontroller board?

The CAD files that @TimWescott referenced contain the PCB layout (in the schematic zip, not necessarily where you would expect it). As typical for ST, they are in Altium. The footprints look like this:...
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2 votes

How to infer resistor size from the manual of this microcontroller board?

A solder bridge is either a blob of solder across two specially shaped pads, or a 0-ohm resistor, also called a jumper. That's it! The name of the thing itself tells you what to use to short it: ...
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2 votes
Accepted

What will be the equivalent resistance in this situation?

This problem is a good example of why diagonal schematic symbols/connections can make it more difficult to interpret schematics correctly. Re-drawing the circuit without the diagonals should make ...
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2 votes

Do I need a resistor for my doorbell wiring?

Stepping up your voltage is a mistake. It won't do what you want, because you misunderstand the problem. When a smart doorbell is wired up with 2 wires, it powers itself (recharges its battery) by ...
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1 vote

Current limiter for VOD3120AB

You can apply 15 V to 30 V to the Vcc pin, and the device will draw whatever current it requires - no need for any current limiting resistor there. However, the input seems to be an LED, so you will ...
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1 vote
Accepted

How to select current sense resistors for ir2136 ITRIP signal

I expect it might have something to do with the fact that the ITRIP input has an internal Zener diode clamping it to 5.2 volts above Vss. As with any Zener diode clamp, you need a resistor in series ...
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  • 384k
1 vote

Convert speaker level to microphone level

You can use a "DI" (Direct Injection) box that are designed to do just this. There are two types, active and passive. The passive ones typically have a transformer internal which isolates ...
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  • 2,819
1 vote
Accepted

Convert speaker level to microphone level

The 1k resistors don't matter to the recording phone. They set the impedance that the electric piano "sees." Assuming that you will be connecting the "Earphone_Left" and "...
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