Questions tagged [3.3v]

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

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4answers
73 views

Convert digital 12V/7V inputs to 3V3 levels

I'd like to read the digital inputs of my alarm sensor into a microcontroller (mainly PIR and Reed switches). The alarm system and the sensors operate at 12V (actually a tad higher) and the MCU uses 3....
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0answers
38 views

Having trouble finding a good transistor to turn off boost converter with Arduino

I have a 3.3V volt logic level Arduino that is powered by a single lipo cell. Also connected to that lipo cell is a boost converter that boosts the voltage from 3.7V to 170V to drive Nixie tubes. ...
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2answers
46 views

Step up 3.3V to 5V and draw 500mA without a voltage collapse/break down

I would like to step up 3.3V from my power supply with the help of a dc-dc-boost converter to 5V and then I want to draw 500mA by placing a 10 Ohm resistor between the output-pin of the boost-...
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2answers
74 views

Recharging a lipo battery while using it

Right now I am designing a circuit that will charge a lipo battery via usb, using the mcp73831 (at 100mA). The battery voltage(nominal 3.7v) will be regulated to 3.3v to power a microcontroller like ...
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0answers
42 views

MOSFET for 3.3v MCU

I'm building a custom board with ESP32-WROOM-32E that can supply 3.3v trough the GPIO. I need to power a screen using 3.3v power. I'm looking for a way to power off the backlight using the GPIO pins ...
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1answer
47 views

How to change breadboard power supply output voltage?

I recently bought a 3.3/5v power supply like this. I'm powering it with a fresh 9 volt battery and 9 volt to barrel connector cable. Right now, it's on 3.3 volt mode, and I have no idea how to switch ...
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1answer
53 views

Diode instead of LDO

For a cost sensitive application we need a 4V supply for a GSM module and a 3.3V supply for a STM32 MCU and couple of sensors. Would it be possible to use a diode like 1N4148 to drop from 4V to supply ...
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1answer
99 views

How to use the human body as a battery?

I was wondering if you'd be able to extract 5 volts (or even just 3) from the human body. I recently discovered in an experiment that just putting a wet strip of aluminum foil over your forehead can ...
1
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1answer
78 views

Powering the Raspberry Pi zero from printer PCB

I want to convert my simple printer into a network printer with CUPS on Raspberry Pi. I tested everything with Raspberry Pi 4 and it worked perfectly. Now, I want to fit my Raspberry Pi zero inside ...
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1answer
43 views

Using the same ESP8266's GPIO for 3.3v and 5v

I am designing a pcb which should receive various types of sensors. The microcontroller is an ESP32 and the external input are RJ11 linked to I2C GPIOs of the uC. I have already planned a LevelShifter ...
2
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1answer
48 views

Driving a 5V LED on computer chassis with 3.3V

My add-in card uses a pair of pins to drive an external activity LED, with anode "provid[ing] 220 ohm pull-up to +3.3 V". However, the LED that I wish to drive with these pins, is designed ...
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2answers
89 views

3.3V Regulator Overheating

Here is my circuit For some reason my 3.3v regulator is over heating. The regulator is a TLV1117LV33. I've tried everything to try and debug the problem but can't seem to figure out what's wrong ...
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1answer
149 views

Connect two pins on AD009-01T without a relay

I have an IR chip where I want to shortcut two pins (PA2 and PA0) when told so by a 3.3V Arduino. I could do this with a sort of relay, but I want a better way. I thought, that one of the pins needed ...
6
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3answers
844 views

Change voltage without consumption

Is it possible to change voltage without consuming power? I have a 5V Arduino circuit that makes use of a wireless chip (NRF24L01) that runs on 3.3V. My current approach to get 3.3V out of a 5V source ...
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3answers
84 views

USB2 powering 3.3V at 500 mA

I have the above simple requirement, and I'm frankly astonished that I can't find it as a simple chip. My understandings: USB2 provides 5V on its power pins; USB2 assumes 100mA, but will provide ...
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1answer
37 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 ...
1
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1answer
64 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 ...
0
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1answer
38 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
90 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 ...
0
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1answer
21 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
71 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
30 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
93 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 ...
1
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1answer
79 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 ...
3
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2answers
101 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
44 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
102 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
29 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
214 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
49 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 ...
0
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1answer
81 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, ...
1
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1answer
131 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 ...
0
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1answer
142 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 &...
0
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1answer
109 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 ...
0
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2answers
58 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 ...
1
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2answers
553 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 ...
0
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2answers
113 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
156 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 ...
0
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1answer
56 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
81 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
82 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
73 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 ...
5
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2answers
348 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 ...
0
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2answers
204 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 ...
0
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1answer
57 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 ...
0
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1answer
146 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? ...
0
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1answer
809 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 ...
0
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2answers
89 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 ...
0
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1answer
64 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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