# Tag Info

### 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 ...
• 159k
1 vote
Accepted

### 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/...
• 380k
1 vote

• 19.5k

### 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 ...
• 58.1k

### 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 ...
• 70.8k

### 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 ...

### 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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### 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 ...
• 57.7k

### 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. ...
• 69.1k
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,...
• 51.4k
Accepted

### 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-...
• 2,084
Accepted

### 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 ...
• 15k

### 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.
• 5,340
Accepted

### 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 + ...
• 6,620
1 vote
Accepted

### 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
• 12.3k
Accepted

### 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.
• 10k

### 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,...

### 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 ...
• 121k

### 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 ...
• 140k
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 ...
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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### 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 ...
• 469

### 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 ...
• 40.3k
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 ...
• 58.1k
1 vote
Accepted

### 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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### 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 ...
• 10.5k