This tag is nearly useless. Consider using more specific tags to narrow your question down.

learn more… | top users | synonyms

0
votes
1answer
17 views

flow power around button laser module circuit

I have a red laser pen module: http://space-linker.com/Uploadfiles/UploadFile/2010178127739.jpg I want to be able to have it always on. How can I short the button, without having to glue or tape it ...
-1
votes
2answers
46 views

Remove power on magnetic lock

I am looking for help on a project so any ideas are welcome. I want to build a drawer into a table that is held shut by an unseen lock (probably magnetic). The drawer front would have two small ...
0
votes
1answer
45 views

Hartley Oscillator Alternate Oscillation Mode

I've been trying to build a hartley oscillator and have almost succeeded, however my calculations are off by appx 1000 relative to the measured waveform. AND the kicker is that it only works when I ...
0
votes
1answer
48 views

power supply and transfering data from smartphone via jack 3.5mm 4pin

In my Project, I was wondering if I can use the 3.5mm jack (4 pin) to transfer data and as power supply to my small circuit? So I'm just asking if it's possible? and if yes, can someone tell me how ...
1
vote
2answers
49 views

Bit Slice Checker

I'm attempting to use bit-slice design, to implement a circuit which checks if an n-bit binary number A has an even number of 1's in its binary representation. I've decided that the circuit should ...
0
votes
0answers
19 views

Selecting best Heat Sink for tec 12706

how can I find best heat sink for my peltier plate which has following parameter max v=15.2v max I=6A delta Tmax=67 dimension=40*40*3.7 power consumption=91.2 w max operating temp=138c T(hot)=50 c ...
1
vote
1answer
85 views

What is the simplest possible circuit for a wireless on-off switch

On one side I have 5V DC powering an LED, and on the other side I have a button (switch/latch/whatever). What's the simplest circuit for this button to control the state of the LED (hopefully without ...
2
votes
1answer
33 views

How can EEG electrodes pick up EMG signals and still function?

EMG signal is the signal generated by muscle flex. EEG electrodes is the scalp potential generated by neuron firing. EEG is on the order of micro Volts whereas EMG is on the order of mili Volts, this ...
0
votes
2answers
75 views

Making a logic circuit with only NAND GATES?

I am trying to create a logic circuit using only NAND Gates for this expression: (NOT Q AND P) OR R This question has really gotten me stuck! Can somebody please help?
0
votes
0answers
44 views

How to design circuit for robot motor

How to design a circuit which fulfill the requirement below. I am a chemical engineering student which do no have any electrical knowledge but still need to design a circuit for my project. Motor ...
0
votes
2answers
33 views

How can I design a 4-to-16 decoder using two 3-to-8 decoders and 16 two-input AND gates?

I have an idea of how to get started, but not sure where to go from there. Since I am using two 3-8 decoders to develop a 4-to-16 decoder, I want to use 4 inputs out of the two 3-8 decoders. So I'll ...
0
votes
2answers
56 views

What would be the output of A = 0100 and B = 0111 with S = 1 in a 4-bit binary adder-subtractor?

I understand S = 1 means subtraction and S = 0 means addition. So then, the output would be the result of 0100 - 0111. But since it's negative, I'm not sure how it would be represented. I know the ...
0
votes
1answer
43 views

H-bridge problem with TIP122.

I tried to make H-bridge by TIP 122 transistor. I used 9V for a VCC. I used push button to control H-bridge, and it's fine. Then I used Arduino 2560 with two digital pins for driving H-bridge. But the ...
0
votes
1answer
37 views

Measuring the current of a Wheatstone Bridge, given four known resistances and supply voltage

Say I had a Wheatstone Bridge with four known resistances and a supply voltage. How would I go about getting the current across Vg? I understand how to get the voltage Vg using Ohm's Law and ...
-1
votes
0answers
23 views

ABW Automotive DMM [on hold]

I have a 70617 ABW Automotive DMM. I was using it the other day and used the voltage range to measure a laptop backlight when I should have used frequency - accidently. I didn't think this would ...
1
vote
1answer
86 views

How to solve first-order RC circuit?

I've got a question, and I just keep getting myself confused when I try to solve it. The problem asks to find voltage and current and resistor currents transients (the switch is opened at t=0). ...
1
vote
2answers
85 views

Would this circuit work? NPN & PNP transistors ~in parallel:

Want to make a thing to test for both NPN and PNP transistors (using RPi GPIO power) and have sketched a diagram. Can you use both NPN and PNP resistors in parallel like this? Could this circuit ...
0
votes
1answer
65 views

Connecting Microcontroller to Higher potential

I am curious how to determine what voltage is acceptable to connect to a micro-controller through a resistor. From the data sheet the highest voltage on a GPIO is 3.8V. So If I have 5 Volts going ...
0
votes
2answers
56 views

How to stops flickering in high current draw Circuit [on hold]

I have 6v DC circuit that quickly pulses high current LEDs on and off at a fast rate (10ms or less). When the high current LEDs cycle, the low power 5mm LEDs used for power on indication and voltage ...
0
votes
2answers
59 views

Unconnected item on circuit diagram

I'm looking to use a CAN Bus shield with my Arduino. The following is a circuit diagram for it: https://www.sparkfun.com/datasheets/DevTools/Arduino/canbus_shield-v12.pdf I am having trouble reading ...
0
votes
0answers
76 views

What are the different elements on this circuit board?

Can you identify the parts on this thing? I don't understand how it is turning on when I put my finger on it. And besides the LED's, what are the other elements on the board lighting up? Light up ...
0
votes
0answers
26 views

Help solving a 2nd order RC with 3 inputs

I posted a couple of questions lately, all related to the same problem. Whether I had a suitable answer to the particular question asked or not, I tried everything I could think of* without any ...
-3
votes
0answers
22 views

On 3 phase 30A 420V AC circuit, superimposed wave [closed]

On 3 phase 30A 420V AC circuit, is it possible to superimpose 6000 V 0.001A variable HF wave? How can this be achieved and who can configure this requirement.
-2
votes
0answers
89 views

Operation of Logical Gate and Big Challenge

i get confusing on Digital Design Course. Anyone Could Describe why the (1) is different from (2) to (4)?
0
votes
3answers
70 views

Open circuit volts and short circuit amps

I am looking to buy a few solar cells to mess around and learn with and I don't understand what exactly this part in the description is telling me: "...offering 4.5V (open circuit) and 18mA (short ...
-2
votes
0answers
34 views

Safety earth continuity

I would like to know, if there is a simple solution or circuit to test continuity of safety ground cable. I'm designing a machine which should be automatically stopped if the ground fault occurred. ...
-2
votes
5answers
104 views

Design Combinational Circuit

Design circuit which compares two 4-bit unsigned numbers A and B. The circuit should have one output X such that X = 1 whenever A>B X = 0 whenever A≤B You may use any MSI modules as well as any ...
-2
votes
0answers
76 views

Power circuit analysis [closed]

2 questions 1) does anybody on this website have any knowledge of transformers and power system? (just to make sure i'm not on the wrong site) 2) can someone explain how to draw a transformer ...
0
votes
1answer
73 views

How to create a simple circuit with your body

I recently visited a museum with my son, and we both enjoyed an exhibit where there was a partially completed circuit that was completed when you touched the two end points or joined hands and each ...
0
votes
1answer
40 views

I'm getting a noisey/square wave output for my mux/demux?

I am using a "CD74HC4051 High-speed cmos logic analog multiplexer/demultiplexer" I put 5V to VCC, put my oscilloscope probe to the common out/in, put 3.3V to A1 (channel in/out), and have a wire ...
0
votes
2answers
48 views

led wont turn on in series circuit

I have a bike flash light which is consisted of 5 LEDS (red). Which looks like this. I unsoldered three of them and put it in a series circuit using two AAA bateries. The Leds did not turn on. I ...
0
votes
0answers
48 views

how to redesign the circuit to drive a 230V 100W lamp for 5 minutes

I have a circuit , the circuit operates with a siren using a 9v battery the siren used is UM3561 i want to replace the alarm part of the circuit using a RELAy that can drive a 100W 230V lamp for 5 ...
1
vote
2answers
102 views

What is the simplest sound-reacting led circuit?

A few years ago (around 3 years) I've made a very basic circuit to make a led blink to the sound. The circuit a single regulator connected to a USB port to extract 5V, with a 3.3V led, conected to a ...
0
votes
2answers
57 views

how to compensate power drains in dc circuits?

This has been on my mind for a while. Lets just take any electronics device. Lets say a mobile phone or a laptop. They have fixed voltage and current, but some components needs higher voltage/current ...
0
votes
1answer
38 views

Low Breakover Voltage Diac [closed]

I wanted to know if there is commercially available Diacs with Breakover Voltage of 20V or less. I tried to find in the internet but always ending up to Diacs with Breakover Voltage of around 30V or ...
0
votes
2answers
51 views

LED circuit:: current goes through, no light

I have made the following circuit. Using the multimeter,+ on first and - on last LED, I get 8.7 volts. What are possible reasons for no light? I have checked that I got the connections correct ( + to ...
0
votes
1answer
23 views

Mesh current method question here?Is this correct?

We have the circuit in the figure.I have to find Vo in terms of Vi. So I have the system of equations {-Vi+ (1k+1k)I1- 1kI2-5=0 5+1k*I2+I2*1k-I1*1k=0 and Vo=1k*I2 We have 5-Vi=2kI1-I2 and ...
0
votes
3answers
57 views

What is the meaning of negative value of alternating waves?

What does the negative values in AC mean? If we have a symmetrical sine wave with positive and negative amplitudes, then what is the physical significance of negative values? If the answer is ...
-6
votes
3answers
65 views

bulbs in series with individual power [closed]

Three lamps (with individual power of 30W , 40W and 50W ) are connected in series to a source of 100V . What is the voltage to the terminals of the 40W lamp ?
0
votes
0answers
29 views

charging of a fan capacitor using a small lightning arc

i am working on a project of "Harvesting Lightning Energy", where i have developed a demo of a small lightning arc using a mosquito Zapper circuit. and now need to store that charge in a capacitor. we ...
1
vote
1answer
35 views

What type of electrical sensing element is used in Water Quality Monitoring Meters?

What type of electrical sensing element is used in Water Quality Monitoring meters such as those pictured below? I might not be using the correct search terms. Some of these meters monitor Total ...
0
votes
1answer
83 views

LED Circuit:: First row doesn't light

I made the bellow circuit on breadboard, but my first row of leds ( each directly after the resistors) is not lighting up. What are the possible reasons for it? I tried swapping leds around and again, ...
0
votes
1answer
67 views

Circuit for supporting, common anode AND cathode RGB LED Matrices

I'm designing a driver / controller board for 8x8 RGB LED Matrices that then can be daisy chained to e.g. make an 16x64 Matrix or so. So I came up with a couple of designs that I've tested and so ...
1
vote
0answers
33 views

Analysis of first order RC using Matlab

I finished designing the given circuit using Matlab but I am getting some weird output results on oscilloscope. and here is what I did I used the commands to define the R, F , C, and ...
0
votes
0answers
35 views

What is the frequency of IR2155 in this circuit?

What is the frequency of IR2155 in this circuit? I made calculations: f = 1/(1.4*(180kΩ+150Ω)*0.0047uF) = 1/(1.4*180150Ω*4.7*10^-9 F) = 844Hz Please tell me if my calculations are done correctly? ...
1
vote
1answer
26 views

Would T feedback network of transimpedance cause serious distortion?

I am now designing a transimpedance using ADA4062-2 to detect signal from a photodiode. The first image is the equivalent circuit. The signal from PD contains 1kHz sine wave and 2kHz sine wave and ...
2
votes
3answers
266 views

NOR circuit with two switches

I need to make a circuit that results in a 0(off) when one or both switches are closed. I am pretty sure this is a NOR circuit, but I am confused on how to make it assert a 0 when the switch(es) are ...
1
vote
3answers
247 views

Please explain this circuit (CNY70, Zener diode) [closed]

I am trying to build a new (Arduino based) controller for a machine that contains a circuit that uses a CNY70 to detect RPMs in a motor. The circuit takes a 5V input and I accidentally gave it 24 ...
0
votes
1answer
70 views

How can I link battery life to resistivity of a phone PCB?

Are there any equations/relevant explanations that can link resistivity of the "wiring"* (or other components) on a phone's PCB to its battery life, i.e. can I prove that using silver wires would ...
-1
votes
1answer
41 views

How to build a circuit that can record and playback our voice?

I want to build a simple circuit that can record and playback our voice. IC should be small in size and the circuit should never contain any SMD components. Can anybody given any suggestions to build ...