Questions tagged [3.3v]

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128x64 OLED not working on 3.3v

As the title suggests, I bought a 128x64 OLED display that would not work when powered by 3.3v. The description said that the OLED can be powered by a 3v-5v source, but I have only been able to get it ...
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1answer
299 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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3answers
28k 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. ...
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2answers
154 views

atmega8a-pu PORTC not working in 3v3

I have atmega8a-pu and not problem with 5v. but when i connect 3v3 to ...
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1answer
385 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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5answers
1k views

Switching input voltage, with two 3,3V inputs

I'm designing a circuit that can get its power from either a battery or a usb. The regulating of the battery and usb voltages is already done, and is regulated down to 3,3V. If both supplies is ...
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1answer
889 views

3.3V Buck-boost converter outputting voltage too high

I'm using a buck-boost converter RT6150B with fixed 3V3 output. I followed their application notes, and here's my circuit setup: Note: I used 22uF for C4 intead of the recommended 20uF for output ...
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1answer
477 views

Load sharing between 3.3V regulator and LiFePo4 battery

I am trying to design a supply for a relatively low power (<100mA) device with a LifePo4 (14500 format) battery and a USB input. Everything is running at 3.3V, and therefore I would like to avoid ...
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1answer
1k views

Wide voltage range input regulation (24V - 3.3V)

TL; DR: I need a circuit capable of handling input voltages from 24V to 3.3V (with a 10mA/5mA maximum current) and delivering 3.3V to the microcontroller (ESP32) input. Recently, I've been working ...
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3answers
730 views

3.3v regulator problem when sharing power source with LED strip

I have this circuit implemented on a prototype board. The 12v power source is a 4A switching power supply. This powers the 12v LED strip, the 7805 regulator for the Arduino, and the IRU1015-33 3.3v ...
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2answers
505 views

LM338T Output to 5V issue with LM1085-IT 3.3V

I am using 12V , 2A DC power supply as an input to LM338T and LM1085-IT 3.3 , for 5V and 3.3V output respectively. The issue i am facing here is when these both voltage regulators are connected in ...
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1answer
93 views

3.3v current issues [closed]

I am very new to the world of electronics and have run in to an issue with a relay. I have a Wemos chip that has GPIO pins. I measured 3v coming from a pin but it doesn't seem to trigger the 3v relay. ...
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1answer
507 views

Arduino 3.3 V to 5 V to controll Stepper Driver MA860H

I'm currently working on a project with an Arduino Due and Stepper Driver MA860H. The issue I'm running into is translating a step Direction and Pulse from the Arduino Due to the MA860H. The Due has 3....
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2answers
576 views

Why is my 220v - AC/DC 3.3v transformer cutting power when relay comes on?

Being super original I've made a DIY Thermostat with an ESP8266. Being a bit of a novice (I'm learning). I've run in to some sticky bits with my kit. For the most part it works fine, but when turning ...
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2answers
7k views

Powering 3.3v-5V LED strip with 18650 batteries

I have a fun project I want to do. It's really simple: I want to power a long LED strip using a bunch of 18650 batteries. The batteries I use are 4.2v fully charged and about 3.5v when discharged (I ...
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1answer
99 views

Resistors in battery-powered LED device and Arduino

I have tiny christmas tree that has about 20 small LEDs, which are powered by 2 AA-batteries. So I'm assuming the LEDs are 3V (because of 2 AAs). This tree was bought in a store, as is. What I want ...
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2answers
1k views

How can I return an Arduino digital pin to floating state?

I am trying to setup a programmed reset function for a 3.3V BlueTooth module that resets when its reset pin is pulsed LOW for a short period of time. There is a 47K pull-up resistor in the BT module ...
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1answer
6k views

N-channel MOSFET used to control 5V relay from 3.3V ESP8266 pin

Today I "played" with a relay for the first time. I only had an N-channel MOSFET available (an IRLZ44N) and wanted to control the relay from an ESP8266's GPIO pin - i.e. use a 3.3V signal to control ...
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2answers
643 views

mic5504 + esp8266 = going mad

I've a board with an esp8266ex and a flash IC. The main power rail is +5 and it goes into a MIC5504 for 3.3 voltage regulation. The enable pin of the MIC5504 is tied up with a 10k resistor to the +5 ...
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0answers
1k views

VGS(off) for JFET in AGC circuit

I want to use a well known AGC circuit (see below) with 3.3V instead of 5V. The description of the circuit can be found here, and state the following about the JFET: Other JFETs with VGS(OFF) of 5V ...
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1answer
810 views

LDO 3.3V Overheats on DC input and no load

XC6206P332MR 662K 3.3V 200mA TOREX LDO Voltage Regulator SMD SOT-23 The capacitors on Vin and Vout are not too close, maybe 1cm away from the pins, I've tried anything from 0.1uF to 22uf, Im powering ...
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2answers
1k views

How to drive multiple LEDs from a Li-ion battery (with varying voltage)?

I want to supply constant voltage to my LED's but the supply varies from 3.7V to 4.2V (Li-ion battery). I cannot use 3.3V voltage regulator as it will need at least 4.3V voltage at the input but my ...
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3answers
4k views

Can is use the 2N7000 MOSFET to switch 12v from 3.3v?

I want to control some 12V solenoids (SH-04215-015) from a Raspberry Pi Zero W. I believe I need to use a MOSFET transistor to switch from the 3.3V of the GPIO to the 12V the solenoids need. I'm not ...
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5answers
4k views

3V LED Pulse Circuit

I am trying to make a very compact and lightweight circuit that will cause an IR LED to blink on and off at a constant rate, preferably at least once per second but the flashes can be more spaced out. ...
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1answer
724 views

How to use 74LS245 to level up signals form 3.3V to 5V?

I am using FPGA 3.3 V outputs to drive 16x4 character LCD (5 V). I went through the data sheet 74LS245 and found this can be operated at Vcc 5 V and accept input voltages from 2 V. I am confused ...
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2answers
908 views

3.3V step up to 5V using BJT

I'm using an Arduino Blend Micro with outputs that provide only 3.3V and I need to control a MOSFET that needs 5V on its gate. Can I step up the voltage from 3.3V to 5V using a single BJT?
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2answers
2k views

How to shift-up logic signal from 3V3 to 5V for NeoPixel [duplicate]

I'm working with NeoPixel led strip and a microcrontroller which run at 3.3V. As you can read in the NeoPixel documentation using a micro with 3.3V out on pin require the ...
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2answers
208 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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1answer
235 views

Having trouble using Adafruit LM3671

I'm trying to make use of an Adafruit PCB with an LM3671 on it. Note on the PCB layout how the EN pin is connected to Vin via a 100Ω resistor. On the 3.3V output, I've connected a 100Ω resistor and ...
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0answers
280 views

RXD line problem

Hi below is my setup block diagram to understand Setup description: I have two board , board 1 and board 2. Board 2 is third party board we purchase. Board 1 has on board SMPS which convert 230VAC to ...
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1answer
2k views

AMS1117-3.3 from 5VDC show 0.09vdc

Hey all I am having an issue using this AMS1117-3.3 SMD: According to its documents it says its either a fixed or adjustable version? So I hook it up as I see in the documents: The left pin (1) ...
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2answers
169 views

best way to regulate 3v3 from 25.2V (DC)

The circuit maximum voltage is around 25.2V so this is the supply im using, I wonder which one is the best way to get 3v3 with less components count and keeping it cost effective, space is a problem, ...
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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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2answers
4k views

How convert a 3.3v PWM signal to a 5v PWM signal

I want to drive an array of leds with a transistor, no more than 240mA the things is that im dimming them with PWM works fine with 5v PWM but im having problems with 3v3 uc because with full 3v the ...
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1answer
673 views

Fuzzy 3.3V from MC34063

Recently I've made simple buck regulator based on MC34063 from TI. I want to use that to power my SMT32 base application. Voltage on input varies from 9-26V. I've put some part on general purpose ...
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2answers
1k views

Altera Max10 3.3V interface

Regarding Altera's MAX10 Cpld, I got some questions regarding the interface of this CPLD with 3.3V devices. I have set pins to 3.3V LVCMOS and I got this warning message in quartus: "Warning (...
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2answers
5k views

Proper use of CD4504BE Level Shifter IC for SPI

CD4504BE Datasheet: http://www.ti.com/lit/ds/symlink/cd4504b.pdf I've been searching all over the web for a proper example of the use of this IC, but I haven't found anything. My basic application is ...
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2answers
1k views

Li-Po/Li-Ion solar charger and 3.3V stabilized output

I'm working on a project with ESP8266 and I want to power it with solar panel and a Li-Ion/Li-Po backup battery. I searched on google and I found a buck/boost regulator is required to stabilize ...
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1answer
4k views

NodeMCU to control MOSFET, not enough voltage

I'm trying to make a HomeKit device that will turn a component on and off. The component's power supply is 12v at 2amps. I figured I'd put the NodeMCU inline with the power (the component's power ...
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1answer
224 views

Arduino MKR1000 relay transistor

I have recently made an internet controlled switch with an arduino mkr1000 and the software part worked just fine. I'm new to electronics and i have a few questions for the wiring part. I have a opto-...
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4answers
3k views

Driving a fan using a mosfet, do I need a diode?

I am using this BS170 MOSFET to drive a fan using a pwm signal generated by a 3.3V MCU according to the following schematics: (I know about the wrong symbol it's just for the packaging on the PCB) ...
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2answers
16k views

Why do you have to use a voltage divider with HC-05 bluetooth module? (Arduino) [closed]

simulate this circuit – Schematic created using CircuitLab I am trying to connect my bluetooth module to my Arduino but it takes 3.3 volts (the bluetooth module HC-05, The Arduino mega takes 5v)...
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1answer
121 views

Using a DC / DC Converter?

I'm trying to use a MAX541 DAC (datasheet here) with a Tiva LaunchPad (TM4C123G). I've gotten this to work with other DACs, the problem is that that those DACs required 3.3 volts and the MAX541 ...
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1answer
179 views

Efficient alternative to a charge pump for stepping up a 3V supply to 3.3V?

I'm currently using a charge pump ic chip (http://www.digikey.com/product-detail/en/microchip-technology/MCP1252-33X50I-MS/MCP1252-33X50I-MS-ND/529831) for stepping up a 3V coin cell to a 3.3V ...
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1answer
164 views

Need for 3.3V regulator

I have seen several products ( such as the pitft for the raspberry pi, and most other small tft screens) which use a 3.3V regulator on the 5V power rail to provide power to the 3.3V system. In some of ...
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2answers
13k views

Changing a 3.3V signal to a 5V signal using a BJT transistor

I saw someone asking this EE.SE question in a thread over 2 years old and could not really understand some things about the answer. He had a 3.3V input signal that he wanted to change into 5V signal. ...
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5answers
2k views

3.3v to 5v conversion with non-5v tolerant part. (single npn transistor?)

I was wondering if I can convert 3.3v to 5v when the 3.3v part isn't 5v tolerant. I was thinking of using this layout: However I'm not sure if the gpio pin will get 5v "for a second" or if this is ...
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2answers
691 views

Is a 3.3V-5V MCU runnable at “nominal” 3.3V?

I've got some 5V MCUs whose rating is 3.3V Min to 5.5V Max. My question is whether running them at a "nominal" 3.3V is OK. I can imagine that a 3.3V source runs typically at ~3.35V, so no ...
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1answer
81 views

Safe amount of current going into my device?

I am trying to send a signal from an Altera DE2 FPGA to a detector so that I can gate it on and off. The FPGA uses 3.3V logic while the detector uses 5V logic, so I need to increase the voltage on the ...
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1answer
284 views

Interfacing 5V to 3V3 devices - MAX3377 damaging my board

I am using the bidirectional MAX3377 level translator by maxim. I am doing a prototype board and as I test this board piece by piece, everything works until I solder on this part, and my 3v3 rated ...