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452 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 ...
666 views

Where exactly do the electrons go in the circuit once they traverse the circuit elements?

From my understanding, when a voltage is applied to a circuit the free electrons in the circuit elements start moving towards the higher voltage potential. So what happens once the electrons reach the ...
133 views

Is there any such logic gate that accepts inputs from both sides and also stores information within the gate itself?

I'm trying to design a logic circuit that will end up looking a binary tree (there will be a "root" logic gate at the top and a whole bunch of "leaf" logic gates at the bottom). Input is fed as ...
301 views

How would I design a simple logic circuit for 3 input bits?

All - Suppose I have 3 input bits Bit #0 Bit #1 Bit #2 I need to design a logic circuit has follows: Input: Bit #0 = 1, Bit #1 = 1, Bit #2 = 0 Output: 0 Input: Bit #0 = 1, Bit #1 = 0, Bit ...
653 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 ...
237 views

Problem with circuit created with fabric pressure sensor

This is only my second time working with any type of circuitry, so I apologize in advance if I don't use the right terms when I explain my problem. Feel free to correct me! So in one of my projects, ...
265 views

Nodal Analysis of an electrical circuit

I have several doubts about solving circuits. Can any circuit be solved using Nodal Analysis? If some circuit can be solved using Nodal Analysis, can it be solved using Mesh Analysis too? Why do we ...
278 views

Can you tell me how the op-amp in this DMM circuit works?

This is a autoranging DMM circuit. Specifically I would like to know what the lower op amp is for. It seems to be a non-inverting configuration with the (+) terminal at ground, but I don't what it ...
2k views

Metal Halide circuit without a capacitor?

I recently inherited an awesome 4foot 2x250Watt metal halide lighting unit for my marine tank. The previous owner wanted to dump it because one of the lights was flickering and he could not really ...
329 views

Any idea which software was used to generate these circuit diagrams?

And/or: I'm trying to choose a free schematic drawing software, and like the way these two look. I've read related questions about circuit drawing software as well. I like Fritzing, but it lacks ...
597 views

Latching power switch question

I have the following circuit (source: EDN): I understand the basic working principle of the circuit and it works fine when it is powered from a 1.5V source. But when I power the circuit from a 9V ...
245 views

AC analysis from a DC fresh grad/point of view

So i was finished taking DC circuits and im adept at basic laws like KCL, KVL and Ohms. But today im taking AC circuits and i wondered why things dont work well as before. Lets take this example A ...
713 views

How to make a 7 to 3 priority encoder?

I'm trying to make a 7 to 3 priority encoder for a circuit diagram for a class. The problem is that we have to take in a 7 bit number and output a 3 bit answer representing the maximum number of ...
256 views

Basic ac circuit analysis

When are we going to append the "j" term when analyzing ac circuits. When i say j term, im pertaining to opposition to current/impedance. In the image below, notice that Xl is not written as jXl. When ...
2k views

How do the lights on stairs work?

I remember that there's a very simple circuit diagram that explains how there can be 2 light switches for 1 light and that regardless of which switch you turn 'on/off' the light is toggled on/off. ...
241 views

Adding Wifi+ Micro-controller to a device in an economical but production-able way

Is it possible to reliably and economically add Wifi+ Micro-controller(for very simple logic and GPIO) to a non-moving device? I see some wifi soc in the market too. are these a viable options? I am ...
136 views

Minimization of Logical Equations

I have been giving a problem were I have to design 1-bit subtractor, which performs single bit binary subtraction. It has three inputs: the digits ai, bi (bi is subtracted from ai) and the borrow from ...
519 views

RC Circuit, finding time it takes for Voltage across capacitor to rise from 0 to 5V

For the circuit shown below what is the time it takes for Vc to rise from 0 V to 5 V in (second). Assume Vc(0+) = 0 V The answer is $$t = 2ln 2$$ but I am unsure why. What I have so far:  ...
1k views

components within a triangle in an electronics diagram

I'm trying to understand the following circuit diagram: Specifically, the four triangles within the L293D component. So I understand there are two transistors in there, connected in series from 24v ...
363 views

Fundamental question about circuits and grounding

I understand that voltage is relative and that the hot wire in house mains is a nominal $\pm$ 120v in reference to the neutral wire. I also believe the ground wire is connected to the neutral at the ...
776 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: ...
421 views

What is wrong with my 2-bit adder?

I attempted to build an 8-bit adder in Logisim by carefully chaining together a half-adder and 7 full adders, all made from basic logic gates. Unfortunately, it produced erroneous results; for ...
1k views

What is wrong with my D flip-flop toggle switch?

Until a few weeks ago, I had never drawn a circuit diagram in my life, so bear with me. I am currently trying to design (in Logisim) a circuit that acts like a toggle switch, using only basic logic ...
314 views

LED circuit with 17 parallel diodes

I have a parallel LED circuit with with 17 red LEDs. I am using a 555 and microcontroller with a 9V alkaline battery (500mAh). In chasing mode, 3 red LEDs go continuously from right to left, so ...
5k views

What do I need for a basic RF circuit?

I'm looking for any resource that can help me build a very very basic RC circuit. I'm talking as simple as using RF to turn on/off an LED. The purpose of this circuit is for research and education. If ...
152 views

Basic Circuit AND,OR and NOT with 3 LED [closed]

I just started my course in logic design and digital computer circuit how can you create a circuit with AND, OR and NOT connecting it to 3 LED and connects to a DIP? I have trouble understanding this ...
324 views

Is it possible to design a switch circuit with XNOR's truth table value?

We all know XNOR's truth table right : http://en.wikipedia.org/wiki/XNOR_gate... Is it possible to design a switch circuit (not a gate circuit) using XNOR's truth table value. I had tried for 40 mins ...
3k views

P-Channel MOSFET high side switch

I am trying to reduce the power dissipation of a P-Channel MOSFET high side switch. So my question is: is there any way in which this circuit can be modified so that the P-Channel MOSFET will ...
1k views

Why is the voltage across a reverse biased diode equal to source voltage?

Why is it not equal to zero since a reverse biases diode is essentially an open circuit?
1k views

Linear Circuit Analysis: Source Transformation

* source transformation is just a combining and rearranging voltage or current sources. I don't think its a universal term. and I'm stuck. any hint?
652 views

Simplifying a relay network

I'm currently trying to design a relay network for a piece of laboratory equipment (PPMS). I would like to describe what the setup is, what I am doing now, what I hope to do, and how I hope to do it. ...
640 views

What is meant by relative voltage?

Suppose you have a circuit ,you are told that the voltage at point 2 relative to point 1 is -90V, the voltage across R2 is -30V and V0 is 200V. What is the meaning of voltage at 2 relative to 1? ...
215 views

What's passive about the passive sign convetion?

I've heard and read about the passive sign convention, but don't really understand its meaning and importance in solving electric circuits. Is this because of conventional current which flows ...
497 views

transferring raw schematic to breadboard and PCB

i have some schematic from TINA pro, pspice, orcad and the lite. Is there a way to automatically convert it into a both breadboard and PCB layout. This is a bright idea since it will save time. What ...
576 views

Cheap programmable GPS unit?

I'm in the middle of installing GPS tracking into my car using the following guide: http://gizmodo.com/5691724/how-to-track-your-vehicle-on-the-cheap Though I'd like to build something a little ...
72 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 ...
206 views

Beginner Kirchoff Voltage Law in DC circuit

Why is the voltage $V_A = 2.5V$ in this circuit? I know the current in the mesh by applying KVL is: $I = 50 \mu A$ but why is $V_A = \dfrac{V_1}{2} + \dfrac{V_2}{2}$? How do the ...
253 views

Wiring different CREE LEDs together

I would like to create a light source consisting of 6 CREE XP LEDs: 4x XP-E Red - 2.3V @ 700mA Datasheet 1x XP-E White - 3.5V @ 1000mA (Datasheet is the same as above) 1x XP-C Royal Blue - 3.5V @ ...
104 views

Unstable points in a basic memoryless circuit

I have been told that there can be more than a single solution to a circuit, and that some of those solutions might be unstable. As a simple example, a resistor with a constant power source, connected ...
747 views

MOSFET Switch w/ Fast Settle Time for Switching E-Field

Application: I have a copper mesh (10cm x 10cm square) in a vacuum chamber connected to a BNC connector by a 24-cm-long copper wire. The goal is to switch the mesh voltage (referenced to ground) from ...
3k views

RC differentiator circuit explaination

This is the circuit of a basic RC differentiator, with the input/output voltage waveforms. First of all, I don't understand why there is decrease in the output voltage (discharging of charge from ...
132 views

Common sources of acoustic noise in circuits driven by a DC power supply [duplicate]

Possible Duplicate: What electronic component of a computer produces (sound) noise? What are some common sources of acoustic noise in circuits driven by a DC power supply? One potential ...
245 views

Should Shielding GND be isolated from circuit GND?

In my system, I have 3 Grounds: DGND, AGND and Shielding GND, What steps should I take to isolate shielding ground from the other grounds that exist? Should I connect them with ferrites or use some ...
89 views

which battery will supply the load?

I have connected 14V supply terminal from alternator to 12V battery terminal and has taken the load across these terminals . But the load is operating still in 12V, and when measured across the ...
980 views

How can I design a circuit that will turn on when a wire is cut?

I'm trying to build my own cable lock alarm (for science!) and am having trouble figuring out a way to detect that a wire has been cut. The circuit has to Use no power at idle (or at least, very ...
2k views

applying nodal inspection technique to supernodes with dependent sources

I was about to apply nodal analysis via inspection (to make it faster) to the above circuit, yet as we can see, it has a dependent source. so listing the equations for node(1 and2 ) supernode a ...
270 views

Should I use pull up resistors in this configuration?

I am interfacing a 3.3V FPGA to a 5V DSP. I am using this bidirectional voltage transceiver: http://www.nxp.com/documents/data_sheet/GTL2000.pdf In the diagram in page 4 they're using pull up ...
187 views

Recommended placement and routing of an RC Low pass filter

What are the recommended placement and routing techniques for the following RC low pass filter circuit: I made an initial placement and routing that's shown below: Actually it's randomly placed ...