Questions tagged [circuit-design]

a term to describe how a circuit should behaved based on accomplishing a particular task. When designing circuits, one should consider how it works, the target specifications, efficiency, cost effective, code compliant, and ethics.

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Construct a 16x8 memory [closed]

I am very new to this and have no idea how to proceed, I have looked at tutorials. Someone help me. : ) I have to design and simulate a 16x8 memory on logisim.
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Grounding sensors to large bodies

I've attached a diagram of what I'm talking about. I have a large (600x300x10 mm) aluminum block in which I place thermistors to monitor the temperature distribution in the plate (in a standard ...
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How do you cascade two 7-segment decoder ICs together?

We used one 74LS47 IC in our lab, which we connected to a 7-segment display and tested the outputs. Now our instructor has told us to cascade two 7447 ICs together and implement it on a 7-segment ...
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Best method for modulating a voltage by 50mV

Some context - building a flight simulator that replicates a WWII aircraft. I have a dual ammeter/voltmeter that displays amps by using a shunt resistor that generates a 50mV drop from the reference ...
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How many loads can I have on an open drain output?

So I am using this AND gate which has an open drain output. I am trying to determine how many loads that I can place on this output. I see in the datasheet, that the Iol is over 1mA, but I am unsure ...
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Thevenin's theorem for Voltage divider bias

I am calculating the base current of transistor Q1. To simplify the circuit equations, I applied the Thevenin's theorem and converter V1 and R1, R2 into Vth and Rth as shown in the image. Vth= V1x(R2/...
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Do I need a current limiting resistor with an industrial rail DIN optocoupler?

I'm going to use this industrial opto-coupler: Optocoupleur RS PRO, montage Rail DIN, 6 mA In its specs document they don't mention the need of a current limiting resistor. I always add a current ...
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How to derive effective transconductance versus oscillation amplitude in a oscillator?

In the page below in the lecture note shows a plot of effective transconductance versus oscillation amplitude. How is it derived? Or is there any source to derive effective transconductance versus ...
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Activate arc lighter with Arduino

I have a SaberLight plasma arc lighter, and I have taken it apart for a flamethrower project. I would like to use an Arduino Uno to programmatically activate the arc lighter. Using the Arduino Uno, ...
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How to calculate components values for LM3421 in SEPIC mode

How can I calculate the components values for LM3421 in SEPIC mode? In the LM3421 datasheet, there is not much information about SEPIC topology. (Section 9.2.9.2 is labelled "Detailed Design ...
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Breadboard Layout Validation

I have a breadboard with a bridge rectifier circuit that I am hoping to have someone validate for me. The circuit with breadboard pins is: And a picture of my breadboard is: Thank you!
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4 answers
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Can this circuit with two resistors oscillate?

From this lecture note. Can this circuit oscillate as what the lecture said? I did simulate this circuit in LTspice but it doesn't work. The step from 1V to 0V does have many frequency components ...
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I'm trying to simulate an audio amplifier circuit but I couldn't find how to add LM386 to LTSpice like image. Is there any suggestions?

LTspice circuit. I couldn't find solution for this part of my simulation.
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Is there any alternative mechanism of using 7 relays?

I want to control 7 AC bulbs using a microcontroller. Only one bulb will be ON at a time. I can do that using 7 relays. But Is there any alternative mechanism or IC that can do that with low cost, ...
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How to find noise sources from noise figure data?

An amplifier datasheet provides noise measurements that show it has a noise figure of 3dB for R_s = 100Ω and R_s = 10kΩ (same noise figure for both values of R_s) at T=300K and f=10kHz. I need to ...
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2 answers
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Function generator with an operational amplifier

I am solving a function generator whose frequency of each output is 5kHz. My question is, how can I find the parameters of C3, R5 and R6 to get an output of the same frequency? In addition to the ...
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2 answers
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Circuit that switches on at 4V and off at 3V

I'm new to circuit design so please forgive any misstatements. I'm wanting to create a circuit that turns on a device (mini water pump) when a voltage hits 4V or higher and turns off the same device ...
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How can I step down 24V to 5.5V and 3.3V with separate grounds?

I have a 24VDC 4A input that I need to step down to both 5VDC and 3.3VDC, but I need the 24V ground plane to be separate (isolated) from the 5V and 3.3V plane (these can have a shared ground). What ...
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1 answer
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Connecting two motors to one Arduino board

I am making a project where I will be using two different motors. One is a 6V DC pump motor and the other is a servo motor. The two motors are not supposed to operate at the same time. The user will ...
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3 votes
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Why is each time constant in this transfer function equal to "open circuit" time constant not "short circuit" time constant?

From this lecture notes, the open circuit time constant approximation: How to prove the yellow part? The lecture note mentioned Richard Adler at MIT did prove this but I could not able to find his ...
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Piezoelectric Harvester Circuitry

Can anyone tell me what type of circuit is used in this piezoelectric harvester? And if possible, could you also provide a diagram of it when connected to battery?
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How would one build a circuit board without hiring a manufacturer?

Assuming one had access to old CPUs, ram, hard drives, and mainboards with I/O connections and BIOS chips and other chips in them. I know the basics of the gates to make CPUs and RAM, and I know it's ...
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Clear D Flip Flop when FF input is not equal to 1

I am trying to implement magnitude comparators with storage as a D FF. In this picture, if X is equal to 0, second AND gate on magnitude comparator (that comparator in rectangle) will give 1, as Q' &...
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1 vote
1 answer
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USB-C passthrough (including CC line) not making connection

I'm trying to make a USB-C switcher. I'm using a rotary switch (center) to have one input USB-C receptacle switch between two output receptacles. This is so I can plug my keyboard into the input and ...
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mosfet to protect reverse plarity from a power suply range 10v-18v DC [duplicate]

hello I have designed a board that operates on 10v to 18v DC (2A) I need somehow to protect it from reverse polarity, am thinking to use MOSFET but how I can drive the gate in 10v-18v range
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Is there any meaning attached to the Zener diode symbol?

Is there any meaning to the Zener diode symbol? The triangle is similar to a normal diode which originally indicated current flowing in one direction only. Is there any hidden meaning to the yellow ...
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One freewheeling diode for two relays? [duplicate]

I have two separate relays, both with different part numbers and coil inductances. Both are driven with the same 12V 'control signal.' When the control signal is removed, the inductance of both coils ...
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2 votes
2 answers
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MOSFET gate-source protection, in selecting a Zener diode, is there any consequence of the forward voltage / current rating?

In a design, I have Zener diode used for the protection of a MOSFET's gate and source as shown in the picture below. I'm comparing two diodes for this purpose, and most of the spec values are equal, ...
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How can KCL be satisfied here?

In the transistor biasing using diode below assume that at time t1 the circuit is stable and apply KCL at the junction of the three devices you have: ...
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1 vote
1 answer
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Using a square wave function to select output

Im new here! I been having some trouble thinking about a circuit wich selects one of two outputs based in the value of a square wave function like this To put some numbers Freqs Vin=1Hz Vout1=1kHz ...
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3 votes
2 answers
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Would appreciate some tips on designing simple OpAmp circuit

I've recently posted this question regarding input impedance when working with DC signal on HCPL-7840 Isolation Amplifier. The answers were very clarifying and helpful, but I've come to realize I need ...
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2 answers
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How can I control a firework igniter (e-match) with Arduino?

As the title says, I'm looking to light one firework igniter with an Arduino Uno but I'm a bit of a noob to electronics. From the little I could find online, it looks like I'd need to use a relay? But ...
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2 votes
1 answer
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Correct way of estimating delays in FPGAs

What is the correct way of estimating delays when doing operations in Verilog? For example: reg [31:0] a, b; ... wire [31:0] res; assing res = a + b; The above <...
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TEC cold side temperature decreases, then increases rapidly [closed]

first post to this stack exchange. Self teaching on TEC circuits. I bought a diymore TEC1-12706 12V 60W 6A. Note no heat sink installed on the TEC. To test the TEC I put together a series circuit as ...
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2 votes
1 answer
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Bandpass filter doesn't work when implementing PCB

I have been trying to make a 5th-order Chebyshev filter going from 500 MHz - 570 MHz and a 3rd-order Chebyshev filter going from 500 MHz - 540 MHz. This is my first time making a filter into a PCB. No ...
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1 answer
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Trace to Pin connection

I am having the issue of connecting my voltage regulator to the trace. The trace must be thick but the pins are too small. What is the best solution? I am using proteus. Does making a solder Paste ...
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1 vote
2 answers
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Switch off 2 power supplies using a single switch in a feedback loop

We have setup a solar stairwell project at home, using LED and salvaged batteries and this is what it looks like: However it may look, the circuit can be oversimplified to: simulate this circuit &...
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LTspice JFET Voltage Divider Bias Configuration

I want to simulate this circuit in LTspice program and find Idss,Vp and Idsq,Vdsq but cannot. How can i simulate transfer characteristic?
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1 vote
1 answer
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Buck converter bias supply

I am using an MP2325 buck converter (datasheet) to drop a 24v supply down to 5v to supply a Raspberry Pi. The datasheet above details ...
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3 answers
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Water level indicator using CMOS inverter

I want to build the below circuit. The circuit has three levels to indicate water. low->o/p LED. Medium->O/P LED. High->O/P LED + Buzzer. Each level has two types of MOSFET; they work as CMOS ...
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-2 votes
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AC or DC input to DC output SMPS circuit design

I want to design an SMPS circuit with the following specifications: Input can be either 33-265 VAC or 48-375 VDC Multiple DC outputs (eg. 5VDC, 10VDC etc. ) Output power (40-100W) I am not able to ...
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2 answers
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What would the output impedance of the circuit below be?

My analysis is as follows, the auxiliary amplifier with input Vb is being used to sample the output current of the main amplifier (NMOS on the bottom) and return a voltage to its gate. So it is ...
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2 votes
1 answer
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Designing GPS matching network with TESEO and chip antenna

I am new to designing for RF and have a question regarding the design of the matching network for a GPS module I am working on. The datasheet of the chip antenna ANT161575ST-1202A1 recommends a ...
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1 vote
0 answers
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TP4056 circuit - have I got this right?

I've designed and built this circuit which seems to work, but this isn't my day job so if anyone's able to take a look at it and let me know if you can see any flaws or potential improvements I'd be ...
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5 votes
1 answer
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Voltage on battery-backed SRAM somehow higher than both battery and regulated supply

I'm using an AS6C1008 SRAM chip, and I'm having an odd issue with it. The voltage supply going to this chip is created from a stiff 5V supply (VDD) and a 3V backup battery (CR2032), diode or-ed ...
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2 answers
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Understanding 24 V PoE mode B magjack connections

Having just realised I have screwed up my board by stupidly swapping pins 4 & 5 on the magjack output, I have realised I don't properly understand the PoE power pins on the magjack. I wonder if ...
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1 vote
3 answers
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What causes the output of the flip-flop to be LOW in 555 timer monostable circuit?

Before pressing the button, the external capacitor isn't charging because of the short circuit applied across it, but the short circuit is happening because discharge transistor is ON because the \$\...
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5 answers
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Circuit shorting creates less resistance

Using only intuition, without mathematics, why can't the total resistance in the circuit of the 1st image be less than the total resistance in the 2nd image? The 2nd circuit gives more path options ...
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1 answer
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How do I connect a female EEG electrode to a breadboard?

Electrode output end: EEG electrode: I'm trying to connect the output of EEG electrodes to a breadboard as input. How do I connect the electrode to the breadboard? Usual jumper wires don't seem to ...
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14 votes
4 answers
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Does each IC need its own bypass capacitor when there are multiple ICs in the same circuit?

I am working on a circuit to measure the current drain of six hobby servos for a robotics application. I'm aiming to use six ACS712 current sensor ICs. The ACS712 data sheet shows a typical ...
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