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0
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1answer
16 views

Bell Detector with Arduino

I am trying to upgrade our existing bell with my arduino to detect whether the bell is used and to mute the bell. The circuit for the bell runs with 9V AC. In order to minimize the wiring I want to ...
0
votes
3answers
48 views

Maximum resistance allowing for short circuits

Consider a contrived circuit consisting of only cell and pot: (1) a cell with constant voltage V and constant amperage A, (2) variable resistor of resistance R initially set to its highest finite ...
0
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2answers
44 views

Best elements for downhole and high temperature circuits

I want to design a data-logger with PIC MCUs. This data-logger is going to work in chamber in the oil wells in the depth o 500 meters. and it is going to record temperature and pressure for 20 hours. ...
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2answers
60 views

What capacitor and resistor to use in my simple circuit?

I’m quite new to electronics but I’m making progress learning about it. I would like to make a circuit to control the speed of two electromotors. (Or two circuits to control separately, whatever is ...
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0answers
40 views

Circuit Certifications [on hold]

Finally got to the stage of designing some simple but useful circuits, I started to wonder how to certify my designs for commercial markets; several questions come to my mind Hoe many certs there ...
1
vote
1answer
65 views

H Bridge Control using Raspberry PI / Micro controller

I am looking for input on this circuit that I have designed. I am currently working on a project called the Net-EEL RC Car. It is an RC car that will be controllable using Network Socket Servers / ...
0
votes
2answers
50 views

dual input temperature comparison circuit

I would like to build a comparator circuit that will compare two varying temperatures and operate a relay to a fan when one is greater than the other, but release the relay if the opposite is true. I ...
0
votes
1answer
79 views

why emitter is connected to high level and collector to low level?

generally, in all switching circuit, emitter is connected to ground and collector is connected to high level. i am not getting why is it so? is there any special purpose?
1
vote
1answer
47 views

Replace crystal earpiece in bat detector circuit

I've been following the instructions on http://pw1.netcom.com/~t-rex/BatDetector.html which includes the following schematic for a Frequency Division Bat Detector circuit: The instructions clearly ...
0
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0answers
25 views

Bypass potentiometer on a Sennheiser PC360 G4me headset [closed]

I have a Sennheiser PC360 G4me headset which makes a crackling noise when using the volume up/down knob. After doing some research it looks like contact spray could do the trick in some cases but for ...
1
vote
4answers
61 views

voltage and current after closing the switch

In this circuit, the switch has been open for a long time that is the 2F capacitance is full. Now we close the switch. what is the equation of the current and voltage of the 2F capacitance after ...
0
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0answers
28 views

open ground in 480volt 3phase [closed]

Is there any component that I can use to detect an open ground on a hoist system? I specifically need a visual flag that will inform me of a broken ground wire!
0
votes
1answer
62 views

How to generate Duty Cycle from DC without 555

I am currently working on a simple circuit which includes creating duty cycle from DC. Also, I need to change it's pulse width with time. I have decided to use op-amp relaxation oscillator to produce ...
0
votes
1answer
54 views

Thevenin Voltage of the circuit [closed]

Suppose I have the following circuit, How do I compute Vth using the node voltages? I simulated a circuit similar to this one with values. I got: Vnode1 = 5.93 kV Vnode2 = 12.4 kV Vnode3 = 5.64 ...
0
votes
1answer
55 views

PSPICE Simulation of Cascode Amplifier Not Working

Can anyone please tell me why I am getting the following "floating node" errors. I have fiddled around with the resistors to see if it affects anything, so these are not the actual values. I have also ...
0
votes
1answer
26 views

Sinusoids and Phasors AC circuit impedance

Hello. I've been doing problems, and transforming from time domain to phasor domain to find input impedances seems simple enough But I've come across a circuit with a dependent voltage source, as ...
1
vote
2answers
42 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 ...
1
vote
1answer
134 views

Is this circuit block diagram correct?

I plan to build a flashlight powered by 360F 2.7V super capacitor (proposed to be charged to max 2.5V and discharged to min voltage of around 0.6V to increase capacitor life). The EMF generated by the ...
1
vote
1answer
63 views

Thevenin Equivalent Circuit

Been solving this for hours please help. My answer is written on ink. The correct answer is given. I tried Nodal Analysis and got Va = -100 V at node A (beside -100V) and then KCL@A: -0.01V1+Va/20k ...
0
votes
2answers
44 views

A short circuit in LC circuit

What happened in a LC circuit when I connect two ends of the Inductor by a wire with very small resistance, at the time the current in the Inductor is $$0 < I < I_{max}$$
1
vote
0answers
58 views

DC-circuit with N-JFET transistor

My task is to decide RD and RS in this circuit: The properties of the N-JFET are Up = -3.5V and IDSS = 10mA. The criteria here is that the operating point should give UDS = 7V and ID = 5 mA. With ...
0
votes
0answers
38 views

Common Drain Design Not Meeting Spec

I am trying to design a Common Drain amplifier with specifications below. I have reworked the problem over 10 times now and have not achieved anywhere near an appropriate solution. I have spelled out ...
1
vote
1answer
38 views

Mesh Analysis on AC circuit

I'm doing a practice problem and I'm unsure how my approach did not receive the same result as the solution. Any help would be appreciated. Below is the Figure along with the solution as well as my ...
0
votes
1answer
36 views

Adder-Subtractor Circuit

For the above question I got the answers: a. SUM = 0110 | C = 1001 b. SUM = 0100 | C = 1010 Are these answers correct and how is the overflow calculated?
0
votes
1answer
47 views

s-Domain Analysis?

I've spent a really long time on this question but any approach I use gives me extremely messy solutions which make it impossible to convert the equations back into the time domain. This is what ...
1
vote
2answers
77 views

Pad hole size for 0.1" Male Headers

I created an Eagle part that has several holes to solder 0.1" pitched break away male headers to, such as the one below. However the pad has a hole thats too narrow for the header! What drill size ...
2
votes
1answer
119 views

Help understanding power amplifier circuit

Below is a single channel power amp circuit from the 1970s. I was wondering if someone could help me understand this circuit from a modular point of view (I'm getting lost with what I presume is ...
1
vote
1answer
133 views

Please rip apart my circuit design

I am making an opensource automated wireless window blind controller. It uses a motor to open and close standard metal blinds. Below are links to the project documentation: Full project page ...
0
votes
2answers
32 views

Trigger Signal Lockout Circuit

I have been trying to design a trigger lockout circuit and I have been having some difficulties. The circuit is taking as an input a 3.3v pulse. These inputs can happen randomly and what I would ...
0
votes
0answers
30 views

Amplify an electret microphone and feed the amplified signal through a piezoelectric disc?

I’m a student and Im trying to use an electret microphone to pick up an audio signal which is then reproduced by a piezoelectric disc as a part of an experiment with sound perception in spaces and ...
1
vote
1answer
102 views

Second-Order RLC Circuit

How do I find the second-order differential equation, in terms of \$i(t)\$? At time \$t>0\$, the voltage source will be gone, and I will have a parallel \$RLC\$. I am having problems with finding ...
1
vote
1answer
36 views

Analyzing a small-signal MOSFET circuit

This is the problem: And this my solution: Is it correct ?
0
votes
0answers
70 views

Analyzing a MOSFET amplifier circuit

This is the problem: And this is my solution: I want to check if it is correct or I've done some mistakes.
3
votes
1answer
98 views

Analyzing a MOSFET circuit

This is the problem: And this is my attempt to solve it: For (1): I don't know how to get vgs or how to use the hint to get rid of it. For (2): I assume that ...
0
votes
0answers
32 views

SIM908c GSM module with Arduino Mega without any shield

I needed to work with GSM so I bought a SIM908c module. Also I bought a breakout board to connect with Arduino Mega. I am using the gsmlib library for this module. My connections are as follows: ...
-1
votes
1answer
50 views

How do we detect when Power Source from EB to DG

Is there a way we can detect if power source switch from EB to DG? Are there any circuits or alarms already there in market which triggers when the power source changes from Normal Power Supply to ...
1
vote
3answers
184 views

How do you calculate the current and voltage when the emitter is grounded for saturation mode

For example, assume you have this transistor with a grounded emitter: Since we are dealing with a saturation mode, \$v_{ce} = 0.2 \$ making the drop across the resistor 9.8 v. The current going ...
2
votes
2answers
366 views

How does a solar garden LED work with just 1 AAA battery?

I am converting some solar LED garden lights to emit infrared light for a raspberry pi critter camera to see what kind of wildlife trifles through my garbage at night. I just have one question. ...
0
votes
2answers
61 views

Examples of one port network

Can anyone give me some examples of one port network, explaining its significance? Actually I just want to know whether or not such one port network exists? If they do,what are they used for.
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votes
3answers
47 views
-2
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2answers
80 views

Paralel RC time constant [closed]

In parallel RC circuit, what is the behavior of current of capacitor C1? What is the time constant?
0
votes
0answers
36 views

24 Hour Counter JK Flip Flop

I'm trying to implement a 24 hour clock circuit using JK Flip Flops. I've gotten the minute part but I am having trouble designing the hours part, specifically the ones section. If it should count ...
0
votes
1answer
56 views

Help understanding the function of my circuit. (Bug swatter)

The important thing is the image below. I want to know how it works. Here's what I understand so far. First I'll identify the pieces: -The blue "packet" is a capacitor. Its a \$ 0.030 \mu F\$ ...
0
votes
1answer
35 views

Doubt regarding Combination of Cells

I was unsure of what the voltmeter would read: the terminal voltage of the top cell, or the voltage across the parallel combination of cells. I tried calculating both ways, but both give the same ...
2
votes
2answers
106 views

Equivalent Resistance? [duplicate]

How do you find the equivalent resistance here? (I realized it's a Wheatstone bridge, but it's unbalanced, so that doesn't help.) I tried using Kirchhoff's laws, but there is no cell given.
1
vote
1answer
64 views

How does the power supply noise generated by digital ICs affect the output of regulator?

I have learned that the digital ICs would generate the power noise in the power supply line,however, I am not so clear about how. In my opinion, two contributors: the change of the current would lead ...
2
votes
3answers
147 views

Questions on Operational Amplifiers

What I've learned so far from Navy school is that operational amplifiers are used as a substitute for transistor amplifiers and they contain three main circuits: the differential amplifier, common ...
2
votes
2answers
57 views

Solving a Thevenin equivalent circuit

Suppose \$R_{1}\$ and \$R_{2}\$ are replaced by resistors of unknown values which are different from those assumed in part (a). Using a variable external voltage source, a student applies \$+1.5V\$ ...
0
votes
2answers
78 views

Electric current of inductor

I have a homework problem that was solved by our instructor: "Calculate the electric current of the inductor at \$t=0^+\$." He calculated \$1/30\$ but the answer sheet was says \$-1/30\$. Which ...
0
votes
1answer
40 views

Whats the difference between these three breakout boards for the ADXL345 Accelerometer?

I would like to use the ADXL345 in a schematic im working on right now, but as there is no typical/minimal circuit provided within the datasheet i got stuck. I did a bit of research and found three ...