# Questions tagged [circuit-design]

The process of creating a circuit to accomplish a particular task. When designing a circuit, one should consider how it should work, the target specifications, efficiency, cost effectiveness, code compliance, and ethics.

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79 views

### Limiting voltage on voltage monitoring pin

Question: How do I limit the voltage on a voltage monitoring pin to 28 V DC (due to voltage rating) when the power rail voltage to be measured may go up to 48 V DC continuous? Are there DC-DC ...
49 views

### Simple square wave frequency multiplier/divider

I have a square wave 0-12 V input signal that varies from 30-150 Hz, which I wish to multiply to an output square wave 0-12 V signal of 60-300 Hz. In this case, the multiplier is 2, however I ideally ...
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47 views

### Servo moving to limits randomly

I've seen a very similar question to this but want some extra pair of eyes on my circuit here. The issue I've encountered is on startup of this script every so often the servos will randomly move to ...
75 views

### Is it good idea to use diodes at DC inputs? [closed]

I made a 3.3V ESP32 module circuit with a 12V DC adaptor. 12V DC is stepped down to 5V via a buck convertor and fed into Vin of ESP32. ESP32 module was also connected to my computer via data cable. I ...
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### Does it make sense to place ground plane "island" within power plane layer for return paths of traces on adjacent layers?

I have the following layer stack up: Layer 1: Components and traces Layer 2: Dedicated ground plane Layer 3: Power plane Layer 4: Additional traces as needed I have read (I'm a beginner at circuit ...
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91 views

### Is there an analog circuit that rounds voltage or current to digital-like values?

Is there a simpler circuit than basically using an ADC followed by a DAC for this?
118 views

### RC circuit equation why have negative sign

I'm reading a book named The Art of Electronics. What are some of the features of circuits with capacitors? To answer this question, let’s begin with the simple RC circuit (Figure 1.31). Application ...
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1 vote
75 views

### Will this circuit design of a simple slayer exciter circuit work?

I have been looking at different designs for a simple slayer exciter circuit and have attempted to create a circuit diagram for it based on what I have seen from some other designs online. I just ...
105 views

### The role of Q33 and the connection of pre-discharge circuit in the BMS circuit

I'm trying to understand the following circuit which is taken from the TI's TIDA-010216: I don't understand the role of Q19, D29, D30 and Q33 in the circuit. According to this post, it seems that Q19,...
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1 vote
59 views

### Circuit schema 2 ways WS2812 connect with 1 PCB layout

Hey all I am having a difficut time trying to figure out how to go about the following: I am wanting to just make 1 pcb but I am using WS2812B LEDs and therefore needs to be in the correct direction. ...
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### Help understanding simple Arduino circuit from a datasheet example

I'm trying to use a water sensor in a new design, and I don't understand the example circuit that is given in the datasheet, even though it looks very very simple. I must be missing something. Any ...
101 views

### Is hardwiring considered as a good practice?

I'm a second-semester CE student, and in our programming courses, they say that it's a bad practice to hardcode things, because compilers are geniuses and can optimize everything! However, I'm sure ...
57 views

### Designing battery voltage measurement with passive balancing

At work I have been busy designing a circuit for measuring the voltages of three batteries that are connected in series to each other. A microcontroller will read the voltages and determine which is ...
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1 vote
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### Question / Help with K Map and Circuit Diagram

I am currently working on a 7-Segment Hex Decoder and keep running into a issue with the decoder. I have tried many times to make a circuit based off the K-Map and table of values but ultimately fail ...
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34 views

### Proteus 8 issue [closed]

I imported a Voltage Regulator model Library(AMS1117 3.3V) from Digikey/Snap-EDA. However, no matter what configuration I use, output voltage is always zero.
48 views

### How soft start circuit works, LTspice simulation [closed]

Please help for the attached circuit, further explain how soft start circuit works in M2 (PMOS) with RC circuit, computation and the voltage divider with zener diode with BJT (PNP), how it works, for ...
88 views

### Do you know this circuit? [duplicate]

I was checking the flipper Zero Wi-Fi Developer Board schematics and in the power section I bumped with this circuit, but I've never saw it before. Someone knows the name of the circuit or its purpose....
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1 vote
35 views

### Help Needed for Solar Battery Charger Design Using CN3795

I have created a solar battery charger using the CN3795 IC. The goal is for the panel to output 2A at 5V. The panel characteristics are as follows: 50W, Vmp of 17.22V, and Imp of 2.91A. For the ...
85 views

### 30MHz signal that could drive a 100W load

I'm seeking an AC source or signal generator for a RF application with the following specifications: Output bandwidth: 0-30MHz Power output: 100W (necessary for sustaining a plasma) The issue I'm ...
• 1,163
1 vote
53 views

### RC Integrator Simulation

I am simulating an RC integrator using an ideal opamp. I model the opamp as two different models (one with vcvs and the other with vccs) as shown in the below two cases. When I ran the ac simulation, ...
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### How can I drive a MOSFET with high input capacitance using discrete transistors? [duplicate]

Driving MOSFETS at high frequency is hard, especially if the MOSFET has high input capacitance (as high power MOSFETS typically do). There exist dedicated ICs to drive such MOSFETs. However, for my ...
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### Designing a simple toy dashboard

I would like to make a "car dashboard" simulator as a gift for my kid. Nothing too complicated. Here are my initial thoughts, and I would like to hear your opinions - where I was wrong, what ...
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1 vote
54 views

### How do I generate a trigger signal from a periodic analog signal having varying amplitude [closed]

I have an analog signal detecting a periodic vibration of low frequency (<100Hz) and want to generate a pulse whenever the signal crosses a certain threshold. The challenge is that the amplitude of ...
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1 vote
35 views

Hello I am attempting to build a simple load cycler that will charge and discharge 3.7 V 18650 batteries for a certain number of cycles. I would like to program it to do something like this: I'm not ...
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85 views

### How to approach the highlighted part of the question?

The boolean expression for Z for the four input module came out to be A0A1A2+A0A2A3+A0A1A3+A1A2A3 I am attaching my work here.
1 vote
103 views

### custom PCB design for UART-TTL to STM32

I have a project where I am using an stm32f103c8t6 to send a 10Hz pulse (as a hard trigger for a camera) and sends data through UART to a connected computer. I'm using this opportunity to learn PCB ...
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80 views

### Understanding taser circuit with MOSFET and push pull transformer

I'm trying to understand the circuit pictured. It's a circuit for a stun gun. I understand the function of the first capacitor at the front, but I'm having difficulty understanding how the push pull ...
70 views

### Power supply gives at most 20 millivolts

I have a power supply KIKUSUI MODEL PAB 250-0.25A (photo below). The voltage source used to work correctly, but my roommates have used it for a while and now ...
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1 vote
112 views

### Programmable pulsed current power supply

I am wanting to build a lab-scale or benchtop power supply circuit which can produce theoretically square (practically trapezoidal-ish) pulses of frequency and duty cycle that can be set via Arduino/...
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### PCB inverter design

While prototyping a inverter or a power converter on bread boards we use separate power supply for microcontrollers and separate supply for gate triggering. But how to design a PCB for an inverter or ...
83 views

### Driving 2xP-channel MOSFETs with a single N-channel?

I would like get some feedback on the given subject. I want to control the N-channel MOSFET using a microcontroller and use 2xP-channel MOSFETs to increase the current capability. What I'm doing as ...
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### Is putting capacitors in both ESP32 and HX711 overkill in this circuit?

I was getting erratic readings from my HX711, which was receiving power supply from my ESP32. I figured it was catching noise and power fluctuations from my ESP32. So I added a 0.1 μF capacitor and a ...
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### ESP32-WROOM-32UE cannot be powered and loaded with firmware

I designed a custom ESP32 board (schematic attached). I am using an ESP32-WROOM-32UE. My schematic is based on the ESP32-Devkitc-V4 board from Espressif (schematic attached). When I connect the board ...
78 views

### Detecting 12V using MCU

I am trying to detect a 12V input signal coming in from a DC wall charger using an STM8 microcontroller. I am using a voltage divider with 10k/2.2k : First there is a 10K resistor in series with the ...
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### Switched Capacitor Non-Inverting Amplifier

I have been studying switched-capacitor circuits recently. I have come across one question with regards to the switched-capacitor non-inverting amplifier circuit shown below. It is made up of ...
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48 views

### What should I do when clearance boundaries overlap with SMD pins?

I am brand new to layout design. I am using the TPS62136RGXR buck converter in my design. However, according to the attached image, the pin's clearance boundaries (0.2mm according to JLCPCB's assembly ...
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32 views

### Help needed for verifying 3.3 V wireless charging schematic with LIR927 battery

I am currently working on a small electronics project for my swimming club and could use some advice. Forgive me if this is basic, I'm really new to electronics. I am working on a wireless charging ...
1 vote
60 views

### Choose Transistor and Op-Amp for Constant Current Source Driven by Microcontroller

for my project I am trying to provide a current source to a heater (load in the diagram) on a PID loop to keep an object at constant temperature. A thermocouple is attached that reads the temperature. ...
24 views

I am testing a vcvs and trying to use it as an ideal OP. This is what I observed when I tried to set a "maximum output voltage" to the vcvs. This is the simple vcvs schematic. VIP: AC=0.5, ...
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642 views

### How do we measure inductance with a DC source?

I just got this question asked by a Staff Engineer for an entry-mid level job at a large company, and I suspect the interviewer might be wrong here. I had this interview on Monday and I got a ...
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149 views

### What is the purpose of this circuit inside a solar lamp?

I'm trying to get started with electronics, just as a side quest. I found this little circuit inside a solar lamp I had. I'm trying to understand what its purpose is and why it uses its components, ...
1 vote
37 views

### Circuit design for a timer and relay

I'm designing a timer circuit that detects white cards with black stripes, which needs to be inserted in a specific position to activate. The black stripe sensor must remain disabled when the card is ...
52 views

### Problem with the triggering the 555 monostable trigger

I am currently making a dual speed dc motor circuit that is controlled by 555 timers. My goal is to have DC motor full speed below 2V and between 2-3V, the DC motor spins half-speed using PWM from 555 ...
1 vote
82 views

### How do you utilize a voltage signal from a subcircuit when developing a larger circuit?

I am trying to understand how circuits are built. In my experience learning about circuits, I have learned all about analysis techniques for circuits that start with a complete circuit and ask, "...
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### How to design a battery charging circuit for solar panels and USB

I'm working on a low-power project using an esp32 and an e-paper display which will be used indoors. It uses a lithium ion battery. I want to harness solar power so the battery has be manually charged ...
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118 views

### Is my solution to this differential receiver circuit calculation correct?

I solved the difference receiver circuit problem in the picture with the following formula but I am not sure of its correctness because I do not have an answer key. I would like to discuss whether it ...
61 views

### Finding it hard to track connections when they are under the protoboard/perfboard

What I really like about creating the connections underneath the protoboard/perfboard is that you can create really compact circuits. Also, since there's no insulation, it's easier to make multiple ...
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### Simple circuit to bypass preamp when battery fails

A guitar has an on-board battery powered pre-amp between the pickups and the output jack. This is great until the battery fails, when it goes dead until the battery is replaced. I would like to have a ...
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### Why does the author assume $R_{in} = 1/ g_m$ for this this circuit?

The following circuit is from Chapter 13 of Analog Design Essentials, page 1324, written by Willy Sansen. Calculate $R_{in}$ for this circuit. The author thinks $R_{in} = 1 / g_m$ However,  -...
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1 vote