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Questions tagged [3.3v]

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1answer
185 views

Raspberry Pi Pico 3.3V_EN pin control voltage inquiry

I am trying to turn on or off a Raspberry Pi Pico using a Raspberry Pi Model 3. The Raspberry Pi Pico seems to have a 3.3V_EN ping which is basically the 3.3V regulator enable pin (3V3_EN) pulled up ...
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1answer
144 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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1answer
29 views

Can RFM98PW 3V3 Regulator Cause Heating

I'm using RFM98PW RF module that is supplied by 5 volts. This module has SX1278 on board which is supplied by 3V3. So there is a 3V3 regulator on board. As you can see in the diagram below there is a ...
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1answer
204 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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2answers
210 views

PMOS reverse polarized - 12v light

I've this circuit: simulate this circuit – Schematic created using CircuitLab I have a doubt, when I press the SW1 the LAMP1 turns on, when I press the SW2 the light turns on but the P channel ...
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0answers
41 views

CAN Transceiver circuit problem with TJA1042T/3

I am a novice designer who recently started designing circuits. Using the STM32f407VGT MCU operating at 3.3V, using the CAN1TX(PB9) CAN1RX(PB8) pins, the circuit was configured by referring to NXP's ...
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1answer
60 views

stm32 nucleo 3.3V usage

This is probably an easy question. When using an STM32 Nucleo powered by a 5V power supply, can I use its 3V3 pin to supply 50mA? Or do I need to use for instance a 3V3 linear regulator attached to my ...
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2answers
44 views

splitting ground plane

I have a 4 layer board, where I have a 3.3V STM32 and some 3.3V components, and also a 24V H bridge to drive a 24V DC motor. The board is supplied with a 24V DC power supply, the 3.3V is created by a ...
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votes
3answers
439 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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2answers
1k views

Driving a 24V isolated load from a 3.3V MCU

I am looking to drive a 12-24V purely resistive load from a 3.3V MCU. I would like to use an opto-isolator to separate the circuits electrically. I've drawn up the following circuit, but I'm not ...
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1answer
390 views

Connect 240v PIR motion detector to Raspberry Pi

I want to connect a 240V PIR motion detector directly to my Raspberry Pi 3. Inside its plastic case I found 2 PCBs. One is the power supply board which has a 24VDC relay, a S9013 NPN transistor, ...
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2answers
186 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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1answer
51 views

How to choose a resistor value for Wheatstone bridge such that it is a balanced circuit?

I have a 3V sine wave input and I want to measure resistor precisely from 1 ohm to 40ohm. I have tried using Arduino to measure the resistor using voltage divider but it became obvious that I will not ...
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1answer
39 views

How can i turn a DPST button in to a DPDT?

How can i turn a DPST button in to a DPDT? I've replaced all the stock rocker switches in UTV, got all 14 of them done except for one all to Push Buttons. The push buttons are SPDT, "on/on" ...
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1answer
315 views

How does this USART level shifter circuit work?

I'd like to ask how this circuit works: I understand how it works in principle, but not technically. It's a USART voltage level shifter. It's supposed to divide 5V to 3.3V by a resistor divider, in ...
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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
110 views

Can I drive a motor directly with GPIO pins?

I have a Raspberry Pi Zero with a DC motor attached (directly) to gpio. According to the Raspberry Pi Foundation: The operating voltage of the GPIO pins is 3.3v with a maximum current draw of 16mA. ...
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3answers
395 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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4answers
115 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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2answers
64 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
222 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
67 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
76 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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6answers
4k views

How to blink an LED (~5Hz) at 3.3V (coin battery) with minimal components to save power?

I need to build a circuit to blink an LED (about 5Hz) with a coin battery, so on 3.3V. Main specifics: Single coin battery (3.3V.) The LED is an SMD5050 with 3V and 100mA maximum. I would save ...
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votes
1answer
60 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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votes
1answer
115 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
127 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 ...
0
votes
1answer
482 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 ...
1
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1answer
66 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
votes
1answer
57 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
133 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 ...
6
votes
3answers
896 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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votes
3answers
132 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 ...
0
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1answer
43 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
vote
1answer
70 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
votes
1answer
41 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
173 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 ...
4
votes
3answers
29k views

Resistor requirement for 3.3v

I have a quick questions: can I safely power a LED with 3.3v without a resistor? I have some LEDs that I typically power with 5v and a 220Ω resistor, but I can only supply 3.3v at the moment. ...
0
votes
1answer
24 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 ...
0
votes
3answers
182 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 ...
3
votes
2answers
149 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 ...
0
votes
1answer
61 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....
0
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1answer
156 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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0answers
53 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 ...
0
votes
0answers
42 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 ...
1
vote
1answer
114 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 ...
0
votes
1answer
104 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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0answers
30 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
795 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 ...
1
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0answers
56 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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