Questions tagged [conductance]

A direct measure of how well a material conducts with higher numerical values meaning that the conductor conducts better. It is the inverse of resistance. The units of conductivity are \$ \Omega^{-1}\$ - not to be confused with conductivity that is similar.

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1answer
50 views

Effective resistance of a NMOS

How do we calculate effective resistance of a NMOS, operating in linear region across drain and source?
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1answer
174 views

How to build a human chain detection circuit?

I've seen devices that detect a human chain. For example, they detect when 1 or more people (possibly several) hold hands to close a circuit between two distant metal objects. I've tried to find ...
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Combining ECG and EDA (skin conductance) in the same chest electrodes. Possible and how could it be done?

Currently I'm designing a wearable, battery powered module that combines several sensors into a single device. In this device are modules for both ECG measurement (heart beat) and EDA (skin ...
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2answers
95 views

Transfer function of Operational Amplifier

I am trying to solve the following operational amplifier circuit to get its transfer function. I have tried two different approaches, one is elementary approach by finding V- and V+ and equating ...
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1answer
552 views

Resistance of twin core wire

I'm trying to do a problem for revision and I'm running into problems calculating the resistance of this circuit used to approximate a twin-core wire. It's used later in the question with the middle ...
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2answers
2k views

What does it says the transconductance efficiency (gm/Id) in an amplifier?

I understand the concept of the transconductance but it's not clear what does the transconductance efficiency (gm/Id) mean. Since gm is the variation of Id to the Vgs or vin voltage... What is the ...
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581 views

Light LED light?

I would like to mount 10 or 20 white LED on a thin rod, about 2 m long - and around 3 mm in diameter. I will need to accept various compromises for conflicting requirements, but I try to understand ...
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774 views

Should I ground an aluminum front panel?

I am building a power supply and it will be housed in a plastic case with a fan. I understand the wisdom of grounding a metal case, but in my case (no pun intended) I have an aluminum front panel. ...
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712 views

Value of omega from forced response V0

Based on figure. Maybe a simple question, but I'd like to know why that if forced response is zero, then $$\omega L = \frac{1}{\omega C}$$ where \$L\$ is the inductance and \$C\$ is the ...
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145 views

Calculating R with 2 resistors parallel

I've ran into a slight confusion. The equation for resistance in a parallel circuit should work for any number of resistors, I assumed. So when I'd have 2 resistors in parallel, total Rt would be: ...
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3answers
12k views

Conductance in a transmission line

I'm just trying to clarify the transmission line concepts in my head. Now wikipedia (that great source of always reliable information) defines the conductance in the transmission line as ...
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2answers
540 views

Simple circuit reacts to touching a node

I am trying to repeat a circuit from this post. For some reason it does not work properly, and trying to fix it I figure out strange behavior. LED turns on if I touch R3 with my finger or with ...
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1answer
2k views

Use water as a conductor for a circuit powered by 1.5v battery

I've tried to create this quite simple circuit. V1: 1.5 v (AA battery) LAMP1: 1.5 v, 0.2 a (E10 incandescent light bulb) "Salt water": 10 ml regular water + 1 g salt When I connect the wires ...
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4k views

Why can't electrons leave the surface of a conductor?

At room temperature, no free electrons can ever leave the surface of the metal. A free electron cannot escape the coulomb (electric) attractive forces presented by the positive metal ions in the ...
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Is conductivity equivalent to conductance per unit length?

Conductivity is measured in units \$S/m\$. Conductance is units \$S\$, and length is units \$m\$, so conductance per length would also be \$S/m\$. Does this mean conductivity and conductance per ...
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How to find electrical conductivity from frequency in my PLC project

I am using a 555 timer which is supposed to measure the electrical conductivity of milk. Here's a circuit for a conductivity sensor: It provides the needed isolation, uses AC measurement, and the ...
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Why does solder not conduct sometimes?

I was reflowing and a 2K 603 resistor partially tombstoned. There was solder connecting the lead to the pad, yet my DMM showed an open. When I heated both ends and the resistor came down and contacted ...