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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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Effective resistance integrator circuit

I know that R1 is in parallel with R2+R3 No it isn't; R2 and R3 both connect to ground. I'm puzzled about the effective resistance that the opamp will see. I'm assuming you mean the resistance/...
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1 vote

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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1 vote

Nichrome strip and resistor

No. You must choose a different nichrome gauge to get the right resistance for the length you can use, or make many turns in that distance but spaced adequately apart on insulators, preferably Mica. ...
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How to use dependent source in Proteus?

Try amending your circuit as per this: - In microcap, I get the right answer: -
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3 votes

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

What does a pull-up or pull-down resistor actually "pull"? The input voltage to the pin. (The voltage is "pulled" towards VCC or GND if there is nothing else driving the signal.) ...
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2 votes

Crystal oscillator - Gain

For a point of reference, think of the gain stage that is used for crystal oscillator in a microcontroller. This is often a simple NMOS/PMOS un-buffered inverter configuration that is DC-biased near ...
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3 votes

Crystal oscillator - Gain

If you are wanting a square wave output such as for a microcontroller then you keep the gain reasonably high because you want the inverting gate's output (such as in a Pierce oscillator) to saturate ...
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4 votes
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Why is resistor temperature coefficient given in a +/- number?

A PTC or NTC resistor is designed to have a large tempco. A PTC may have a nominal TCR of (let's say) +2000 ppm/C. Now this 2000 wouldn't be exact, due to material, manufacturing and measurement ...
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2 votes

Why is resistor temperature coefficient given in a +/- number?

don't standard resistors always increase resistance with temperature? No, they can rise or they can fall. Making a resistor to have a very low temperature coefficient is tricky to do and requires a ...
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7 votes
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Line level to microphone level to record

Your attenuation ratio is too high - the resulting signal is so weak that the phone has to amplify it to make it usably loud. It also amplifies the noise. Your attentuator's impedance is too high. ...
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7 votes

Why is resistor temperature coefficient given in a +/- number?

In order to get better performance, resistor makers use materials and constructions that often result in a more complex curve, especially for high precision resistors. Here, from a major resistor ...
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1 vote

Line level to microphone level to record

A TRRS jack supplies a bias voltage for the microphone, so you would need to add a capacitor to block this voltage. Probably something in the 1 to 10µF range would work. You might also look into using ...
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0 votes

Why do R and C have to be small for differentiator circuit

Assuming RC is small, we want to solve: $$RC\frac{dV_{in}}{dt}=V+RC\frac{dV}{dt}.$$ I was a bit unsatisfied as to why we would neglect the term RCV'(t) on the right, but not RCVin'(t) on the left. So ...
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2 votes

Power Rating of a HV resistor

If I do parse your question correctly, this is what you are trying to do: Test a cap with high AC-Voltages at a fixed RMS current of 0.1A Crank up the voltage until the cap fails Protect your circuit ...
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Do I need a current limiting resistor with an industrial rail DIN optocoupler?

Does these pictures in the RS data sheet help you understand: - The 6 mA will probably be when the voltage input is at a maximum or, there may be internal circuits that keep it fairly constant over ...
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1 vote
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What happens if a ceramic power resistor is heated well past its rating?

If you run the resistor at a higher and higher power (and amount of time) as listed in the "Short time overload" you will begin to degrade the internal materials. Most likely at some point ...
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-4 votes

Which way to read this five band resistor?

10's - 1's - 10ths - tolerance (always gold or silver) - temperature coefficient. Gold/Silver is the fourth band. These colors are not used elsewhere. Yours is 10.5K Ohms, tolerance is 5%, temp ...
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17 votes
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Which way to read this five band resistor?

If you measured 1 Mohm it is about right. It's a 1 Mohm 5% special resistor. It is not clear why you think it is burned, as it looks just fine and measures accordingly, so there is no reason to ...
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3 votes

Can I use lower wattage resistor if I’m using a high voltage power supply?

Ohm's Law is your friend. $$P = I^2R$$ If you know the current and resistor value you can find how many watts it will dissipate, and then select one that gives some safety margin, at least 1 1/2 times ...
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0 votes

How to reduce power drawn by a resistor heater?

Typically, industrial power supply is 3-phase. You can split power between 3 phases (3 heaters, star or triangle, depends of voltage you wish) so reduce current through every single phase. Another ...
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How can I minimize the variance in voltage drop across transistors - or eliminate transistors from this design?

The ADC doesn't measure a voltage. Well, it does, but that's not how it does it. The ADC measures a ratio. That ratio happens to be in terms of a voltage, so yes, you measure voltage with it, but you'...
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1 vote

Using a potentiometer to shift between negative outputs from either -2V and 2V

You have a 5k potentiometer, and you want 4V across it from end to end. That means that 0.8mA should be flowing through it (V/R = I). Your total supply is 10V, and you need to lose 6V of that across ...
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-2 votes

Will a resistor reduce voltage without current flow?

I = (Vbat-Vbemf) / R (including motor DCR, switch R and blower shunt equivalent resistance) ...... but when the motor rotates it also generates back emf voltage, Vemf, so the current reduces when it ...
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2 votes
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Will a resistor reduce voltage without current flow?

Ohm's law says the the voltage drop across a resistor is equal to the resistance of the resistor times the current through the resistor. $$V=I*R$$ So as your experiment proved, no current, no voltage ...
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2 votes

How to reduce power drawn by a resistor heater?

In addition to other answers, the simplest approach I can think of is to reduce the diameter of the wire. That will increase the resistance and drop the power. In addition, the smaller-diameter wire ...
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3 votes

How to reduce power drawn by a resistor heater?

220 Volt / 6 Ohms = 36.6 Amps * 220 Volt = 8066 Watts 120 Volt / 6 Ohms = 20 Amps * 120 Volt = 2400 Watts Reduce the voltage. At these currents you likely want a transformer. Or get a 120V power ...
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2 votes

How to reduce power drawn by a resistor heater?

Since your application (electric furnace for fused metal) is not going to need quick reaction times, one flexible way to control the heating power is to use PWM (Pulse Width Modulation), as mentioned ...
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-2 votes

How to reduce power drawn by a resistor heater?

You can put a resistor in series with the 6 ohm heater , in order to reach 2400W of power you will need a smaller than 6 Ohm resistor.
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3 votes

How to reduce power drawn by a resistor heater?

If you need 8067 watts of power to heat whatever it is you're heating, then... you need the watts, can't reduce the power. If you do not need the watts, but find you need less watts, then you can use ...
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7 votes

XKCD 356 puzzle

As DKNguyen mentioned, this mathpages site covers it. This mathpages site also covers the topic. In the above links, you can find this picture: So you can just pick out the right answer from there. ...
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1 vote

Finding the voltage available at the terminals of the battery in a circuit with parallel resistors

The voltage between the terminals of the [battery plus internal resistance] is 21.6 V. If the negative terminal of the [battery plus internal resistance] is Grounded, it is considered to be Zero Volts,...
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9 votes
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Why is capacitor discharge time higher when an LED is included?

The short answer is the "voltage drop" of the diode, but the longer answer is the non-linear I-V characteristic of the diode. In hand-wavy engineering we resort to a simplified piecewise-...
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2 votes
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Finding the "drop in potential" as current moves through a single resistor of a circuit with parallel resistors

The 4.8 A flows out of the battery into the parallel combination of 4 resistors. It should be clear that not all of the current flows through the 10 ohm resistor but only a portion. You have assumed ...
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5 votes

Why is capacitor discharge time higher when an LED is included?

If you’re putting the LED in series with the resistor then the discharge current will be significantly lower, and will drop almost to zero when the capacitors discharge to the forward drop of the LED.
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2 votes
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Finding the voltage available at the terminals of the battery in a circuit with parallel resistors

21.6V is the voltage across your external resistance, after the internal resistance of the battery. If you are taking the - terminal of the battery to be your ground (0V), the voltage at the + ...
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1 vote
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Finding resistance for parallel resistors: how is my reasoning incorrect, and what is the correct reasoning?

It looks like you do not see what path the current is taking in this circuit. This may be handy
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2 votes
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What limits the heating power output of a resistor heater?

Your heater specifications are as shown below. 20 AWG (2mm diameter) Nichrome wire can carry much more than 26.24 A. 15 m of wire would be required per phase to wind an air-heating element.
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3 votes

What limits the heating power output of a resistor heater?

Don't buy anything without a datasheet unless you know exactly what to expect. You link only translates to Material composition resistance wire, base: iron-chromium-aluminum (FeCrAl). low resistance,...
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3 votes

What limits the heating power output of a resistor heater?

will it draw more power the shorter it is? Yes, assuming your power supply is able to provide enough current. if so, will it stop working past certain point due to temperature being too high? The ...
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2 votes

Should I use a resistor in series when connecting a pin to logic level high?

On your datasheet, the table on page 7 gives the logic thresholds as low max of 0.4 V, high min of 1.3 V. The absolute max ratings allow 0 to 6 V on PEN2. This means it can be connected directly to a ...
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1 vote

Should I use a resistor in series when connecting a pin to logic level high?

For ATE testability, resistors are used, but not necessary for CMOS, otherwise. However for TTL due to failure modes with reverse Vbe inputs >5.5 V a current limiting 10k resistor can be shared by ...
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1 vote

How to use resistors to lower voltage?

A resistor has a voltage drop across it equal to resistance (in ohms) times current (in amps). So if there's something like an LED where, for example, you want 10mA at 1.8V and you're starting with 3V,...
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0 votes

How to use resistors to lower voltage?

1 resistor by itself cannot lower voltage , more than 1 resistors can by forming a voltage divider. The values of the resistors must be chosen such that the output impedance is at least x10 value of ...
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0 votes

How does this tone generator circuit work?

In general, this is called a 'relaxation oscillator'. These work by using feedback to create a toggling (astable) non-linear circuit. The feedback path for this circuit is the 20nF 'whistle chip' that ...
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1 vote

Driving a LED with a potentiometer in parallel, electronic basics

In comment, you cleared up what "perfect LED" meant. If it has a threshold voltage Vth, then your circuit can be replaced by simulate this circuit – Schematic created using CircuitLab ...
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1 vote
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Driving a LED with a potentiometer in parallel, electronic basics

Your circuit is: simulate this circuit – Schematic created using CircuitLab with example values filled in. Recognise that D1 is piecewise: conducting or not conducting (not open or closed). ...
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2 votes

What is the tradeoff in decreasing the frequency bandwidth when reducing noise of a resistor?

Halving bandwidth is the same as taking two measurements and averaging them together. The trade off is that it takes twice as long and you'll potentially average away any rapidly changing component ...
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3 votes

What is the tradeoff in decreasing the frequency bandwidth when reducing noise of a resistor?

It all depends on the application. If you're building an audio amplifier and want to minimize thermal noise, you can decrease the bandwidth of your amplifier. The tradeoff of course is that you can'...
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6 votes

What is the tradeoff in decreasing the frequency bandwidth when reducing noise of a resistor?

It depends on your application. You need to provide the bandwidth that your application requires. If you reduce the bandwidth below that value, you will reduce the resistor noise at the expense of ...
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