Questions tagged [3.3v]

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3answers
352 views

Sampling a +/- 12v signal with a 0-3.3v micro pin

It's been ages since I've had to use my old school notes. I am trying to get an esp32 to read an analog voltage that ranges from -12 to +12. Obviously, the 3.3v esp32 won't like those voltages so I ...
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1answer
101 views

Using ESP8266 to read digital input pin to be notified when motion is detected from 24VDC source device

Software developer here, trying to mess around with hardware (VERY NOVICE) and implement neat things around the house using ESP8266s and Arduinos. I have a commercial wall plug that is activated when ...
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1answer
182 views

How can I protect LDO NCP1117 from overheating due to short at output?

I use NCP1117 to supply voltage to various chips, such as the STM32 and buffer driver, voltage sensor, digital insulator ect. But if any of these chips fail, the LDO will heat up. What should I do? ...
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1answer
1k views

Rectifier circuit for ACS712 with 3.3V ADC

I'm using an ACS712-5A hall effect current sensor that output a voltage roughly between 1.5V to 3.5V. I'm am measuring a main AC power line at 50Hz. I'm using and ESP32 which has a built-in ADC with a ...
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2answers
103 views

Trigger distant camera using 3.3V

I need to trigger a camera using a 3.3V signal, the camera is at the end of a 3 meter cable. This camera has two trigger inputs, a 3.3V GPIO input and an optocoupler input with max input of 30V. I ...
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1answer
85 views

Ensuring 'common' ground on my devboard : powering externally, + JTAG + VirtualCom with USB

Before I ask, I did see other similar posts, but it's not easy for me to apply them (I'm not an experienced EE..). My question in brief is, how to get common ground, to avoid potential gremlins. (Or, ...
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2answers
102 views

Charging a battery without overloading the rest of the circuit

I have a charger circuit (BMS) V1 which charges my LiFePo4 V2 battery, the battery also attaches to a circuit which can take a little more than 3.3v, however if for what ever reason the battery fails ...
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1answer
76 views

ICSP (pickit2) on 3.3v dsPIC33

I'm using a dsPIC33FJ64MC202 (@3.3V) for some project. I normally program my PIC projects with MPLABX through a PICkit 2, but I never tried using it on a 3.3V chip. Will it work? I know the target ...
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2answers
486 views

Best way to connect 5V to GND from ESP (3.3V) - transistor or optocoupler?

First of all: I read through some of the suggested topics (i.e. connecting a 5V relay to an ESP), but to my (limited) understanding, this seems not to be the problem I'm trying to solve. If it is, ...
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3answers
1k views

LM1117 3.3 output gives 4.2

I used this circuit and formula as a reference for 5V to 3.3V It's from the LM1117 datasheet but output gives 4.2V. Here is my circuit: I changed resistors with different values but output give ...
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2answers
363 views

How to use a MOSFET driver directly to drive DC motors with PWM?

I need to control a DC motor runs at 9v with PWM signal 3.3V vpeak. I found MOSFET driver noninverting MCP1401. Can this MOSFET be used directly with a Back EMF diode (diode as usual across the ...
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3answers
183 views

How to interface a C64/Atari joystick port with the ESP8266 (level shifting from 5 to 3.3V)?

I'm working on a device based on an ESP8266 (Wemos D1 Mini) that shall be connected to a C64 or Atari 8-Bit computer's joystick port. At the same time, a normal joystick could be connected (signals ...
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2answers
3k views

Using a FQP30N06L MOSFET on a 3.3v microcontroller

I'm trying to drive a 2.5A/12V load controlled by a 3.3v micro-controller. In the past I've used a TIP120. In this case I'm trying to drive a solenoid and the voltage drop I'm getting across the ...
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3answers
327 views

Why “Supports 5V VCC operation” appeared in LVC family datasheets?

Looking into the LVC logic chip family I was aure that it is 3.3 V supply devices. One of our fellows also confirms it here. This manual dated 1999 states that LVC is 5 V tolerant (version A), but not ...
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2answers
428 views

step up from 2 AA to 3.3V [closed]

I've read some related questions, but I was not able to find/understand a proper solution I'm using 2 AA batteries to power a SAMD21 MCU (arduino mkr series), a DS18B20 probe and a MCP3424 ADC. My ...
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3answers
1k views

Designing reverse and overvoltage protection at 3.3V

I have a barrel jack powered design that I'm making, but I would like to prevent damage in the case of reverse polarity (sleeve is positive instead of negative) and overvoltage (plugging in a 12V ...
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4answers
3k views

How to measure AC current using ACS712 and interface with ESP32?

Actually, I want to measure the AC current using ACS712 connect with ESP32 module. I know this module only works under 3.3v. So, I used voltage divider circuit and step down 5v to 3.3v which is being ...
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1answer
78 views

Would this switching power supply work?

I'm trying to design an integrated power supply to use in IoT projects that I'm working on, some including microcontrollers like the ESP8266 or ESP32. In previous projects I've made, power supply ...
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2answers
265 views

How can I get a loud noise out of a 15mm piezo disc?

I need to get an as loud as possible noise out of a 15mm piezo disc, using only the 3V from Arduino. I know I will have to make some sort of amplifier circuit, and I have attempted to make a basic ...
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2answers
923 views

0-3.3V to 0-5V step by step [closed]

I have a 3.3V microcontroller. I want to use dac. I will work 0-5V range. But my microcontroller has max voltage 3.3v. I want to use a amplifier. I wait your recommendation. note: how can i this. ...
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0answers
98 views

What is the most sane way to switch between 5v and 3.3v on a PCB on the same lines?

I apologize for the blasphemy I may spit during this question, I am a newbie in electronics. That said, I want to design a PCB that will house an ESP8266, the chip I selected provides both 5v and 3....
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1answer
183 views

Low current RPi GPIO inverter

What is the lowest current way of inverting the output from a GPIO pin? I have a solar board that has an add-on that can turn a USB port power off if a LiPO gets below 3.3v. The problem is, they ...
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0answers
159 views

Need a Negative to Positive Level Shifter

I did a simple differantial amplifer for 0-3.3V output. But, as you see I got -3.3V output because gain. I need a shifter circuitry for non-negative output. Can someone help me? Thanks a lot.
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1answer
90 views

Increase voltage drop required to saturate PNP BJT to avoid noise

I have this circuit which must signal +3.3V or 0V depending on the switch status. The the switch is about 20 meters away and is getting EMI from mains. I realized that it only takes -0.7V of ...
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1answer
3k views

RS-485 using USART or UART port on STM32

On STM32F405 MCUs there are USART ports as well as UART ports available. If I need to implement RS-485 communication then which one of these should be used, USART or UART? Or are both of them equally ...
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2answers
1k views

How to operate 1602 LCD on 3.3V [closed]

I wonder if its possible to run a common 16x2 LCD with 3.3v power supply. Its datasheet shows supply voltage = 5V. Are there any 3.3V variants of 16x2 LCD modules?
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1answer
628 views

5V Current Transducer to 3.3V Analog GPIO Input

I am trying to find 3.3V variant of the 5V Current Transducer LTS_25-NP but so far no success. Is it possible to interface this 5V analog output to 3.3V STM32F407 analog input GPIOs? Edit: I want to ...
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1answer
69 views

SOPs for converting a digital circuit from 5V to 3.3V

I am in the middle of an exercise in which I have to upgrade an old motor driver circuit. The old circuit has an MCU and all its logic based on Vdd=5V. I have to use a new MCU whose Vdd=3.3V. So now I ...
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1answer
915 views

HC vs LVC for 3.3V Logic

I am designing a circuit in which Vdd=3.3V. I have checked datasheets of hex inverters 74HC04 and 74LVC04 and both of these can work good at 3.3V logic circuits. If I have to select one of them then ...
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3answers
995 views

Interfacing GPIO 3.3V to 74HC04 5V

Will it be safe if I connect STM32F407 GPIO outputs (Vdd=3.3V) to 74HC04 hex Inverter inputs (Vdd=5V)? What is the best recommended method to add an inverter at the output of STM32F407 MCU? edit: ...
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3answers
1k views

Use 5v Linear Regulator and LDO 3.3V

I am designing a PCB with a STM32 microcontroller, a GPS, DataLogger and X-Bee module. The power supply is a 12V Battery. So in my project I need 5V and 3.3V, at the same time. I don't know if it is ...
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3answers
69 views

Limiting the current into Raspberry Pi GPIO pin

I have a dc dc regulator which can output .35A Current at 3.3V. I just need to check that the voltage it is producing is 3.3V by connecting it's output into one of the GPIO pins of Pi. So i was ...
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2answers
925 views

AMS vs LD vs ZLDO vs NCP in 1117 Linear Regulators

I was in the process of choosing a 3.3V Linear Regulator for my ESP based Project when I stumbled upon the different types of these voltage regulators. The 1117 regulator had different prefixes, AMS, ...
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2answers
1k views

3.3V I2C SDA/SCL but 1.8V VDD?

I'm trying to avoid the use of a level shifter in a design, but it would unfortunately require that I communicate at different voltage levels than what I power the device at. If I communicate with a ...
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1answer
42 views

Combating voltage drop on low voltage distance sensor

I have a distance measuring sensor unit that I am having some issues with, its a Sharp GP2Y0D815Z0F Digital Distance Sensor (Datasheet) that takes a 2.7-6.2v DC input. When plugged directly into my 3....
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1answer
633 views

ATmega328P running on 3.3V using a CH340G as serial to USB interface

I'm trying to use a CH340G chip with an ATmega328P that is running on 3.3V to have a simple serial to USB interface. The available datasheets for this chip seem to be very minimal so I've tried ...
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1answer
67 views

si7021 with 5V MCU [duplicate]

i need to connect Si7021 wich is an 3.3v I2C humidity sensor with Arduino, this sensor has open drain SCL and SDA drivers. is it possible to connect this sensor directly to Arduino 5V?.
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1answer
165 views

Feeding AMS1117-5V with 3.3V [closed]

I need that an Arduino NANO clone work with 3.3V. Can an AMS1117-5V give 3.3V if supplied with only 3.3V? edit: current consumption is 400mA max. the AMS1117 output current is 800mA.
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1answer
176 views

Help with supplying 3.3v to ESP and temperature/humidity sensor

I'm new to electronics. I've built this: It's an ESP-01 Wifi chip and a DHT22 temperature/humidity sensor. Now I'd like to power it with batteries instead of an Arduino. The ESP-01 requires 215 mA, ...
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1answer
620 views

5V to 3.3V for bluetooth module - Is a voltage divider ok?

So I purchased the JDY-10 BLE 4.0 module and a very small MCU which only is capable of feeding 5v. Since I'm not an electrical engineer, I've been reading a bit on the internet, and so far, I ...
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2answers
230 views

Suitable transistors for adaptive motorcycle light project

simulate this circuit – Schematic created using CircuitLab I am working on something very similar to this, Adaptive LED Headlights – Model 8790 Adaptive 2 as a hobby project. I have controller ...
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1answer
567 views

Switching a 3v motor with a MOSFET using a 3.3v signal

****I have knowledge of programming but VERY little experience with electronics.**** I'm attempting to switch a MOSFET using a 3.3v signal from an Adafruit MCU module (Adafruit Module here). The ...
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1answer
287 views

ESP8266 module emits random/garbage characters on external supply (but works on arduino's 5v & 3.3v)

Summary: With arduino's 5v & 3.3v supply , ESP8266 module emits boot messages and responds to AT commands on serial terminal@115200 baud as - boot message: ...
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2answers
620 views

Arduino Nano disconnecting from PC on plugging in 3.3v NRF24L01 into PCB

I've built this PCB which includes two I2C port expanders, an Arduino nano, inputs for buttons and encoders, and headers to plug in an NRF24L01 board. Currently, I just have code running to read two ...
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1answer
244 views

High pitch sound coming from Low-Dropout Linear Regulator (1117 3.3V) setup

I am using the below schematic to drop voltage from 5V to 3.3V (1117 3.3V - http://www.farnell.com/datasheets/2100276.pdf?_ga=2.141255921.210515873.1532314816-790306462.1508240417) for a Wifi Micro-...
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2answers
598 views

Reduce supply from 4V to 3.3V

What is the simplest and cheaper way to have 3.3V 0.5A from 4V? I'm developing a board which uses a SIM800 so it must have 4V 2A power input from 24V external power supply (I'm using a LM2596S adj, ...
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3answers
420 views

OpAmp VS Voltage Divider VS Buck Converter (Current Sensor Output)

I'm working on part of a project and I need to build the circuit that reads the current through a phase of a motor using this IC from Allegro. Assuming there will be no more than 5A, and using a VCC=...
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1answer
843 views

Alternate to LM386 for 3.3V system [closed]

I'm trying control the volume of a small speaker (8Ω, 1/4W) in a 3.3V system using a potentiometer wheel (10kΩ). I've done this in the past using an LM386 in 5V systems, but the project I'...
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0answers
261 views

Turn ON/OFF 5V 2-5A by Raspberry Pi GPIO

I need to control few 5V 2-5A devices by rpi GPIOs, which has the 3.3V logic level. I come up with a simple circuit, but I'll appreciate any ideas, corrections, suggestions. The LOAD is something like ...
0
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1answer
360 views

Drive 12V 1A with 3.3V 10mA (the cheap & easy way)

I found many disussions on the internet regarding this issue, but as an engineering noob I cannot get a proper circuit working :( What I want to achieve: I want to control the ignition line of a car ...