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0
votes
1answer
60 views

PCB Board drawing high current when little bit of liquid gets into it. How to debug the board?

I am new to circuit design and debugging them. I have recently helped in building a PCB with certain kind of circuits on it which includes opamp, boost converter, microcontroller and accelerometer. ...
0
votes
2answers
151 views

what is Rail to Rail supply? [on hold]

I am new to analog electronics and I have been hearing this word from my seniors they always talk about Rail-Rail supply while working on some amplifiers and Opamp,also while calculating and designing ...
0
votes
0answers
60 views

Is it possible to describe an unstable circuit in VHDL?

i was reading this (VHDL: Signal assignment question) post and i got curious about an issue that i wander if it could arise writing VHDL code. Is it possible to write the code for an unstable ...
1
vote
2answers
67 views

Which capacitor for DC blocking in audio applications?

Which capacitor (electrolytic, film, ceramic) do you use for DC blocking in audio applications? From what I have seen most people use electrolytic capacitors. But, also from power decoupling theory ...
0
votes
1answer
46 views

How to use an E-Stop rated at 10A for higher current application?

Most of the E-stops are rated at 10A or less. The following blog has explained how to wire an emergency stop http://www.ehow.com/how-does_5151421_do-emergency-stop-buttons-work.html. But from my ...
-8
votes
0answers
39 views

circut.diagram , calculating voltage drop and how many ohms resistors are needed [on hold]

for 5 white, 1/2 watt leds with a power supply of minimum 5 volts ..how many resistors and how many ohms each a resistor would I need .....please draw a circuit diagram with the given details and ...
12
votes
4answers
2k views

Unknown Circuit Symbol

What are these circuit symbols (circled in red) in these diagrams? I am studying high school introductory physics, and this image is from a problem on circuitry in my online course. The problem is ...
0
votes
1answer
88 views

How to modify existing circuit to additionally control it from outside by raspberry?

I found a great circuit for light home automation: circuitdb.com, but I would like it to be more than a momentary light switch bricked up in the wall.I would like to control it by raspberry or ...
2
votes
2answers
157 views

Understanding this LM317 LED Driver circuit

I came across this simple LED Driver circuit ( I am aware of the power losses but just wanted to understand its working) . Now in a Voltage regulator configuration , ADJ is connected to a voltage ...
0
votes
1answer
28 views

Relay sla-05vdc-sl-c is not working on arduino uno and nano

At first time, trying to check this relay modules (I got 2 the same) they both worked nice - no problem. But now I am going tu build the temperature controller for old fridge (it is working ...
0
votes
2answers
50 views

Proteus Circuit LED does not work

I am trying to build a double dice circuit. I tried one example I found from the web. But, I have problems with leds, and I am not very familiar with proteus. Could you please tell me why my LEDs ...
0
votes
3answers
82 views

Non-inverting op amp on breadboard isn't working

I have posted this before and I have another question. I just can't get this working on a breadboard. I don't know what I am doing wrong. My voltage source is from an Arduino UNO which outputs a 5 ...
0
votes
0answers
33 views

Change range of output values of potentiometer

I would like to use a fuel gauge in my car that expects 240 Ohms when the tank is empty and 33 Ohms when full. However, my current fuel sending unit reads 168 Ohms when empty and 34 Ohms when full. ...
0
votes
5answers
99 views

Parallel Resistor Calculation — Higher Equivalent Resistance

\$R_1\$ and \$R_2\$ are in parallel. What should be the value of \$R_2\$ if \$R_1 = 100\Omega\$ and their equivalent resistance is \$1\text{k}\Omega\$?
1
vote
1answer
52 views

Solar cell electrical model from datasheet

I would like to build an electrical model for a solar cell based on its datasheet specifications. As an example, I retrieved one from Digi-Key: ...
-6
votes
0answers
33 views

circuit diagram for 5 1/2 watts leds with 9volts [closed]

I'm gonna need a circuit diagram for 5 LEDs either in parallel or series of 9volts can I get an idea of how to create a circuit ...can u upload a circuit with these specifications ...thank you ..
0
votes
1answer
34 views

Source transformation problem

I have this problem with a source transformation sum that I can't find the answer to. What do I do after these steps? The question: My solutions: Can it be as simple as algaebric addition of ...
1
vote
0answers
42 views

The equivalent circuit for \$V_{in} > 0\$ with the amplitude of \$V_{out}\$

I have a strong mathematical background and I am trying to improve my (poor) physics. If this is not the right stackexchange forum for this subject, I would be grateful if you could refer me to the ...
0
votes
1answer
66 views

Inverting Opamp Simulation

Calculation show Vin should be 1.02V as no current will be drawn towards negative terminal of opamp and Vout should be -1.02V. But simulation show Vin to be 114mV and Vout to be -114mV. There must ...
0
votes
1answer
67 views

How does my digital watch keypad work?

I have had the same digital watch model for many years. Although they inevitably break again and again, I continue to buy the same model (A Casio 53W). I now have quite a collection of them sitting on ...
1
vote
1answer
320 views

How not to waste power with digital inputs?

I am trying to make simple gates with n-MOSFETS, yet I'm not sure how to actually do physical gate inputs correctly. At first, I tried this (a single-pole, single-throw switch from +5V to gate). ...
-3
votes
1answer
63 views

LM386 with power bank [closed]

I made a guitar amp using the LM386 and i power it with a power bank and a sparkfun usb breakout board but the power bank shuts down by itself after 20-30 seconds. I read it's because the circuit ...
0
votes
0answers
68 views

LED Light Trains

G'day, I'm building a table at the moment and I've got old school PCB and components all over it and a 'Danger High Voltage Keep Out' sign in the centre. I had the bright idea of wiring up an 9V LED ...
3
votes
1answer
444 views

Simple transistor circuit with unconnected gate pin acts strangely

My brother and I were playing around with some new transistors we ordered (2n7000 n-channel MOSFETs), trying to make a simple switching circuit: connect a switch, LED turns on; open the switch, LED ...
-1
votes
1answer
46 views

Simple Circuit to stream video [closed]

I want to stream online video to an LCD screen from a phone or tablet. In the circuit will also be an accelerometer, battery, and perhaps a cache (if this would improve streaming). What kinds of parts ...
0
votes
1answer
57 views

Is potential difference is sufficient for charge/current flow?

Suppose there are two points A and B. A is having fewer electrons than B. That is,it is positive with respect to B.If these two points are connected by conductive wire will the current flow? If this ...
0
votes
0answers
35 views

Does connecting different solar panels in parallel affect total current? Are there any dangers? [duplicate]

I've posted this question on another forum as well but got no usable replies. I've done a lot of research but only found info about batteries in parallel, which says higher voltage will charge lower ...
0
votes
0answers
24 views

Capacitor ESR meter IC

G'day All I am working on building an ESR meter for testing capacitors in circuit. I figure I need a circuit capable of generating at least 200kHz. Looking around I found the Exar XR2206 which ...
-2
votes
1answer
166 views

Is there a current multiplier circuit?

Is there an electrical circuit that can be used to multiply the current? If yes, what is it called and how do I make it (circuit diagram)? I have single input, so a collector emitter circuit won't ...
1
vote
1answer
55 views

thermal knife power supply (part 2)

This is "part 2" because my original question has only brought up more queries that i am unable to solve. The first part can be seen here for any who are interested: "Hot-knife"/Thermal ...
1
vote
4answers
120 views

What Happens to Unit If We Divide Two Resistance

My question is very basic. I have a resistance circuit in which two resistances of 2 ohms are connected in parallel. I want to find the equivalent resistance. I know the equivalent resistanve will be ...
0
votes
2answers
65 views

Switching regulator (TI LM2678) not working on load > 100mA

I am a (joung) programmeer and I recently began studying some electronics&AVR programming. I am trying to use a step down voltage regulator (LM2678-5.0) to transform battery voltage (9/12V) into ...
0
votes
0answers
53 views

How do i impedance match two complex impedances?

If i have a source and load both having resistive and capacitive parts to it, what is the best way to go about matching the loads? The source impedance has low resistance around 15ohms but the load ...
1
vote
2answers
72 views

Push-button BCD counter circuit [closed]

I am trying to reinvent the wheel apparently... I want to create a one-digit BCD counter that increases on a button push and resets to zero when reaches nine. I have just finished a circuit for BCD ...
0
votes
2answers
50 views

Is it possible to find the voltage Vx using mesh analysis? if yes, how?

Good day! Is it possible to find the voltage Vx from this network using mesh analysis? any help is greatly appreciated! below is a picture of my work. thank you! Data: I1 = 5A I2 = 3A I3 = 1/3A
0
votes
1answer
84 views

Using Logic Gates to Power a Motor

I want to design a circuit that powers a motor on under certain criteria, and off under other criteria. I built my circuit using switches and a 74ls04 (Inverter) and a 74ls08 (AND) gates. The ...
0
votes
2answers
165 views

Resistor circuit problem

I am having trouble with a circuit: simulate this circuit – Schematic created using CircuitLab I must calculate the voltage across R1.My answer is to first compute the current running ...
0
votes
2answers
54 views

How to wire circuit DC Motor with LED

I'm trying to learn a bit more about forward voltage and OHM's Law but I'm not sure how to wire this circuit. I have: 1 x 4.5 DC motor (Operating Volts: 1.5- 4.5V, Nominal Volts: 4.5V, Current (no ...
0
votes
1answer
96 views

Is there a difference between these two circuts?

simulate this circuit – Schematic created using CircuitLab I am trying to apprehend the concepts of "ground" in electric circuits. There are some excellent answers on SE here on this ...
1
vote
3answers
58 views

Sign of current through a voltage source

simulate this circuit – Schematic created using CircuitLab I am a total newbie to circuits, so please forgive my naivety. My question is the following: When I simulate the above circuit ...
0
votes
1answer
37 views

calculate unknown source potential

In order to prepare for an exam in electro technics I have a specific task: I have the following measurements of an unknown circuit: \$(1)\quad U_{2(1)} = 4.28V \quad @ I_{(1)}=0.67A \$ \$(2)\quad ...
-4
votes
1answer
96 views

Need help in building a simple circuit using transistor

I am new to EE. I am trying to figure out a circuit. I need to make use of resistors,a BC547 and a LED. I am using a 9V power supply. Can you recommend a circuit schematic that uses only the ...
2
votes
1answer
114 views

Why Does the And Gate have Two Transistors on Top?

Wouldn't the left-side part of the diagram function as a nand gate without the two transistors at the beginning? Why are they part of the diagram? Because in the following picture of a nand gate, it's ...
0
votes
2answers
105 views

Calculate voltage and current in an op amp

Hi I have a op amp circuit that i need help in calculating some values (see image, Å=A in further description) The values i have are: ...
0
votes
4answers
133 views

Toggle state between two circuits with two momentary switches

I have two circuits each with their own 1.5v power supply. I would like to toggle state between the two circuits with a switch, so that hitting a momentary switch turns the light off on one and turns ...
1
vote
2answers
69 views

circuit help, voltage doubler

Okay so I am working with an Arduino Uno and the uno only outputs from 0-5 volts. I am using a breadboard and I built the circuit below using a LM471 Op-Amp and I am trying to boost the voltage from ...
-1
votes
0answers
37 views

Raspberry Pi Circuit Problem

I am currently trying to build a robot using raspberry pi. As a power source I am using an battery pack which provides 1.5 A at 8.4 Volt. I set up the circuits so that the power source was connected ...
-2
votes
0answers
70 views

Circuit analysis

for 1, I got the answer as -R2/R1 for 2, Vout= -(R2/R1) * Vin which gave me -0.08 for 3, i think its infinifty but it says the answer is wrong. How do I go about 3 4 5 and 6? for 4, I tried ...
0
votes
1answer
41 views

Different Voltage Battery Backup Circuit

I saw a circuit on a website to make a backup battery circuit for a rechargeable 12v battery circuit. However, I don't anticipate regular power outages, so I believe that one non-rechargeable 9v ...
2
votes
3answers
207 views

“Hot-knife”/Thermal cutter power supply design

Im undertaking a DIY rope cutter project to avoid paying for the ~$150 storebought ones. Many resources online told me to use a light dimmer + transformer configuration and i had planned to go a step ...