Questions tagged [3.3v]

Questions regarding 3.3V level signals, level-shifting, and circuits.

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33 views

Connecting a TCXO to logic buffer

I am trying to connect the O/P from TCXO (FOX Electronics FOX924B. 20 MHz, 2.5 PPM, 3.3 V supply, Output HCMOS VOL = 0.5 V and VOH = 80% of VDD) to 74HC240 buffer, which I am also running at 3.3 V. I ...
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1answer
60 views

load resistor - my setup is valid?

i want to test my output current of transistor 2N3906. I have two questions. Is my setup valid to measure the max load of the (2N3906) transistor? One plug of multimeter is on leftmost pin of PNP ...
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1answer
36 views

My node mcu isnt turning on when connecting 3.3V to VIN [closed]

So I'm trying to wire my node MCU using in with 3.3V and in the multimeter, it's reading the 3.3V being delivered properly by the converter, I also tested for amperage and its consuming 37mA and I don'...
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2answers
61 views

Power on/off 30-50mA module with 3.3V Arduino-like GPIO

In my Arduino 3.3V project I have a problem shutting down a GPS module. When it "sleeps" with a command, it comsumes 2mA which is way too much for my project. To my understanding I have to ...
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1answer
20 views

May I connect 3.6v Li-pol accumulator to 3.3v dc supply?

I have an old Bosch electric owen which has clock and timer on-board. The problem is: on each electricity fail (even milliseconds) this clock resets to the time edit mode and zummer starts to make ...
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3answers
58 views

Mixing 5V Sensors and Devices with 3V3

I'm a programmer, not a wizard. I've read up as much as I can, including the similar questions list from this question, but, they blew by me pretty quick. So here we go: A project I'm doing some ...
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1answer
22 views

Atmega32u4 on 5V. MISO from IC on 3.3V?

I'm running an Atmega32u4 on a 5V circuit. However, I'm also using a Bluetooth IC [MDBT40] on a 3.3V circuit that I'm setting down from 5V with a linear regulator. I'm turning both SCK and MOSI to 3....
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1answer
84 views

High speed logic level converter circuit

I have been trying to make a 3.3V circuit controlled by an Arduino (5V logic.) I have used a logic converter circuit similar to the SparkFun/Adafruit ones. My problem is that whenever i try to ...
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1answer
62 views

Protecting a 3.3V board against a 5V programmer

I'm designing a home automation board with ATmega328. For programming it I'm exposing the appropriate pins via the AVR ISP interface. Now some ICs of the board allow only up to 3.5V power. What are ...
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2answers
91 views

VUSB / +5V selector to safely power KNX project

I'm working on a board that will include a TP-UART IC + an ATMEGA328-AU on the same device. I'm now facing the potential risk of damaging the host computer or the TP-UART IC if I'm mishandling the ...
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0answers
41 views

On/Off latching circuit with a raspberry GPIO 3.3v

I'm currently failing solving my problem. Of course if I would good better in electronic, I would not post my question here but that's life, and any help would be appreciate. Context: I have around 50 ...
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0answers
41 views

Calculation of the resistors values in a voltage divider

I'm working on a circuit where a 3.3v flash memory, which comunicate with SPI protocol, has to be interfaced to an 8-bit PIC microcontroller working at 5v. For the MISO signal there should not be any ...
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1answer
98 views

Diode OR or transistor OR circuit?

I need a circuit that converts a 3.3V signal into a 24V signal. But I also need to be able to activate the 24V signal using a PCB switch. I can do it in two ways, using a diode OR or using a ...
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0answers
26 views

Send a 60Hz trig signal over a 9m cable

I want to send a trig signal over a 9m cable, the signal is around 60Hz (each 15ms it sends a 1ms pulse). In order to avoid electrical interference I convert the 3.3V original signal with the ...
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2answers
85 views

How to do serial communication between 3.3V and 5V devices using THT components?

I know that there are many questions dealing with logic level conversion/shifting between 3.3V and 5V devices, but my goal is to do do this with standard breadboard parts, so either discrete parts or ...
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0answers
47 views

ADC IC I2C problem

I'm trying to run ads7924 using stm32f series. But i2c does not work so I check the i2c line. Between 0R, MCU side 3.3V but ads7924 side 0V. I set pull up setting of MCU internally . What is the ...
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1answer
61 views

Interface 24V signal from one device to 3.3V signal on another device

I have a device A that sends a signal through an optocoupler, this signal travels through a 7m cable and is used by another device B that has a SN74LVC1G17SingleSchmitt-TriggerBuffer powered by 3.3V, ...
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1answer
71 views

ATtiny13A on 3.3V not working

I'm trying to get the ATtiny13A to run on 3.3V which, if I'm not wrong, would be possible. I've programmed the chip using an Arduino Uno. I'm doing a simple blinking LED example and when I power the ...
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1answer
56 views

Can you power a 3.3 led with an arduino 5v output?

I have a led that can handle 10 milliamps at 3.3v. Can I use a voltage divider and a plus resistor to power it from an arduino nano 5v digital pin? Maybe something like this. simulate this circuit &...
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1answer
51 views

Bidirectional 5V-3.3V level shifter and ADS1115 resistor implementation reduction

I’m using the ADS1115 with 5V because my measuring device provides 0 to 5V measurements but since the microcontroller is not tolerant to 5V, I need to shift it down to 3.3V. I plan to use the BSS138 ...
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2answers
50 views

Getting different measurements from power supply vs a battery

to start with, I am very new to the hardware side so don't beat me up too much. For a project I am doing I need to build a couple power rails, one 3.3v and another 24v. The power supply will be from a ...
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2answers
404 views

Best MOSFET to control small 12v load with NodeMCU? [closed]

I am pretty familiar with Arduino, and I will be using a NodeMCU for an upcoming project I'm doing. I have never used a NodeMCU before. I am using it along with a few sensors to turn on and off some ...
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2answers
70 views

STM32F411 Discovery Has to connect to an external 3.3V to power up?

I have an stm32f411E Discovery board and I'm working with it well. After I use it to work with an UART module suddenly it can't not power up anymore. I have to connect its 3.3V pin directly to ...
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2answers
74 views

how to choose level shifters for serial / UART

I have so far been using some MAX3323EEPE chips for shifting between 3.3V and 5V logics on serial / UART communications. This is quite some stuff to solder on a PCB, and the chip is a bit expansive. I ...
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1answer
47 views

teensy 3.5 interfacing with RockBlock 9603

I want to interface a Teensy 3.5: https://www.pjrc.com/store/teensy35.html With a RockBlock 9603: https://www.rock7.com/products-rockblock-9603 I will give 3.3V input to the Teensy, and 5V input ...
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1answer
51 views

How to control ESP-05 power using Arduino (both are 3v3 devices)

I have ESP-05 connected to Arduino Pro Mini. Both are 3v3 devices. I need Arduino to power on/off ESP-05 device using GPIO when needed. Please suggest. I tried to use N Mosfet but that did not work ...
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1answer
70 views

IRLZ44NS mosfet + 3.3v gate

I'm considering using some IRLZ44NS mosfets that I have with an ESP32 that runs at 3.3v. Looking at the datasheet it says: VGS(th) - Gate Threshold Voltage - min: 1.0v, max: 2.0v It seems like this ...
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0answers
32 views

NodeMCU - Are all GND connctions born equal?

I'm designing a PCB which is based on NodeMCU board in its core. On NodeMCU there are some GND pins, most of them are to serve digital outputs/inputs, or external sensors which operate on 3.3V. Vin ...
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2answers
249 views

Capacitor selection for LM3940 LDO regulator

My project requires 3.3v for operation. For the simplicity I want to power it with USB sources and this makes me to add step-down converter/regulator to get 3.3v from 5v line (let's omit input power ...
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2answers
130 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
42 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
118 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
374 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
80 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
56 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
82 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
55 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
175 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
570 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
155 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
124 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
1k 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
208 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
246 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
593 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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3answers
2k 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 ...
0
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1answer
71 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
170 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
484 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
82 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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