Tagged Questions

2
votes
1answer
105 views

Calculation of cutoff frequency in larger circuit

I'm having some difficulties choosing appropriate resistors and capacitors to get specific cutoff frequencies. I guess it's because I'm just considering the single pole components rather then the ...
7
votes
5answers
521 views

Why doesn't the relocation of this resistor affect the circuit's total resistance?

Why does moving the 470Ω resistor in these examples have no effect on the total resistance between A and B? This is a new question regarding the answer given here by @helloworld992.
2
votes
1answer
128 views

How to calculate a simple mixed parallel/series resistor circuit

I'm trying to understand how to calculate resistance in simple mixed parallel and series resister circuit. Below is a question from a worksheet I've been playing with to better understand the topic ...
6
votes
0answers
173 views

What is a good electronics kit for the everyday inventor [duplicate]

I am looking for a good electronics kit with lots of capacitors, trimmers, resistors, pots, diodes, transisters, leds and laser diodes, timers(like the 555), inductors ICs and common microchips, LOTS ...
1
vote
3answers
147 views

Parallel resistor not affecting rest of the circuit

I have been asked the following question: The resistance, r, is not known in fig(1a), why does its value not affect potential at b? By Thévenin's theorem, any arbitrary voltage source can be ...
0
votes
0answers
228 views

How do you directly determine the approx. value of internal resistance of inductor in LC circuit

According to my calculation, it will take 0.005 seconds to charge this circuit to 8 Volts through the 50 ohms resistor. Using $$ V_c = V_s(1-e^{-t/RC}) $$ How do you determine the effective ...
0
votes
2answers
495 views

Connecting 5 12V LEDs in a parallel circuit

I recently bought 5 12V ultra bright LEDs (all identical), and want to hook them up to a battery pack of 8 AA batteries. So I figured I could just make five parallel circuits with one LED in each, and ...
10
votes
3answers
506 views

What is this resistor for in this circuit?

I am studying electronics and I am currently reading/working my way through "Make: Electronics" by Charles Platt. Here is one of the circuit diagrams that he gives for making a basic burglar alarm: ...
1
vote
1answer
70 views

Modifying an old phone to draw less power?

I have a phone that I would like to install in my car as a GPS tracker, using the following guide: http://gizmodo.com/5691724/how-to-track-your-vehicle-on-the-cheap I'd like to keep it hardwired to ...
1
vote
3answers
225 views

what is the magnitude of total voltage in the below circuit?

I was working on some RLC circuits and I found a question something like this. In series RL circuit, \$V_R\$ = 4V and \$V_L\$ = 3V. what is the magnitude of total voltage ? I just thought \$V_T\$ = ...
0
votes
1answer
404 views

Wheatstone circuit not functioning

I have 3 dummy strain gauges suffering no strain (all 120 ohms, G.F=2.1) and the fourth (same characteristics) is meant to pick up torque at 45 degrees on a rod. It has been verified on an external ...
3
votes
1answer
352 views

Can I connect ICs directly together

This is probably answered elsewhere but I can't seem to find it. I have a circuit which uses a Mega8 to drive a couple of ICs as shown in the diagram below. The ISP connectors in the diagram are: ...
1
vote
2answers
184 views

Thevenin Resistance?

I don't understand our professor's explanation for the answer to this problem: An LED is connected in series to a 150ohms pull up resistor and a MOSFET with drain-source resistance of 3ohms. The Pull ...
0
votes
1answer
94 views

Leveraging DC series circuit to power higher voltage LED panel

I have a IKEA RGB Dioder set where each channel requires 12Vdc (& 1.25W), I want to connect this to my Phidget LED 64 Advanced. Each channel on the Phidget can provide a maximum of 5Vdc with ...
3
votes
4answers
302 views

Simple voltage divider question

So two resistors in series can be a voltage divider. So say I have the following circuit - From what I have read the voltage gets split across the resistors based on their resistance. So there will ...
20
votes
3answers
5k views

How do I calculate the required value for a pull-up resistor?

There are many tutorials that use a pull-up or pull-down resistor in conjunction with a switch to avoid a floating ground, e.g. http://www.arduino.cc/en/Tutorial/button Many of these projects ...