Questions tagged [logic-level]

Logic level refers to the output voltage levels of digital logic, which is often 3.3 V or 5 V.

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load sharing circuit power supply and battery with turn off mechanism

I have my power supply VDD with 5 V. If my power supply is connected to the circuit, the MOSFET M1 should block my battery voltage. If the power supply is disconnected (VDD = 0), the transistor M1 ...
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34 views

Connecting Geiger Counters in Coincidence

So for this Geiger Counter kit from mightohm (https://mightyohm.com/blog/products/geiger-counter/), does any one have any suggestions for what circuits to build to connect two detectors in coincidence?...
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63 views

Is it safe to drive a 5V servo using a logic level shift board?

I would like to turn off and on a servo while it is not used. The LV would be 3.3V and the HV would be connected directly to s lithium battery. Could it work if I replace R4 with a servo? What problem ...
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47 views

Logic Converter driving logic level Mosfet Gate

I am wondering if anyone can comment on the feasibility of this circuit. My ultimate goal is to switch a 12V solenoid on and off using a 3.3V microcontroller, but I have had trouble so far. I want to ...
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38 views

MicroUSB to MCU interface with logical level conversion

I'm trying to interface a micro USB port to a microcontroller but I'm not sure about something. The micro USB port will be connected to a computer with a simple USB cable and that will give me a 5V ...
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70 views

Logic level mosfet wont drive solenoid

I am trying to find out why my current mosfet is not working by looking over the datasheet. Ultimately I am just trying to buy a mosfet that I know will work, but I want to understand the datasheets ...
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1answer
74 views

Problem into shifting from 3v3 to 5v using a BJT

I've encountered a problem when I've made a small circuit to shift logic level of my 3v3 MCU to a 5v signal. Probably I've misunderstood usage of BJTs. Here's schematic: As said, my purpose is to ...
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103 views

Logic Level 3.3v to 3.3v or 5v

I have a circuit with two voltage domains that need to talk to each other. One side is always 3.3v, but the other side can either be 3.3v or 5v depending on what physical hardware is connected. The ...
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84 views

Replacing optocoupler with a more reliable and durable device

I am working on a project where I need to have some sort isolation from a machine sending out highs and lows in terms of 24vdc to 0vdc respectively. And I'm using a microcontroller like ESP32 that ...
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56 views

Convert High voltage output ( 15V ) to 5 V

I want to use : DSD 70 Dual Channel Hall Effect Speed Sensor and integrate it with an MCU ( arduino ) atmega , so I have to convert the output of the sensor to 5V to be able to read it by the MCU. Any ...
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64 views

Data Logic Levels Sent From Sensor Are Not Going All The Way Low

I'm having issues receiving data from a 3.3 volt logic level R503 Fingerprint Module that is sent via it's Tx pin using UART. The logic levels are converted to 5 volts using a bi-directional converter....
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71 views

In a NOR gate not connected to any power supply, how can the output be '1' if both of the inputs are '0'? [duplicate]

I was reading about SR Latches and this very weird (and silly) question popped up in my head. Here, when A and B is 0, then Q is 1. Suppose that this NOR gate is lying in air, not connected to any ...
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75 views

Is it possible to use a MAX232 to convert 0 to 5V PWM to 0 to 12V PWM to input to a motor driver requiring 0 to 12V PWM logic?

I'd like to drive a 16kHz PWM signal at 0.5mA into the input of a motor driver expecting logic levels of 0V for LOW and 12V for HIGH, and expecting a PWM signal around this frequency. The PWM signal ...
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49 views

voltage level handled using optocoupler [duplicate]

I want to program at89c2051 chip. I am referring circuit diagram where the optocoupler is used to handle the 2 voltage levels (+12V and +5V). i didn't understand how Pin A0 and A1 will control the ...
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multi-level NAND circuit simple conversion

i am working on understanding the NAND conversion I have just got the basics of two-level NAND conversion and when i went to the book example for a multi-level NAND coversion it used solved an example ...
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42 views

How to read a 5.5V IC push-pull output using a 3.3V microcontroller?

I have two devices that I need connect, one fed with 5V, the other fed with 3.3V, and I also have a level-shifter, TXS0108E, that allows communication between two circuits, one working in 3.3V and ...
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76 views

Correct usage of 74LCX245 logic level converter IC

I am designing a PCB where I need to convert some 5v logic signals from a Wiegand reader into 3.3v logic that a Raspberry Pi can understand. I have been using a resistor-based voltage divider before, ...
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69 views

Amplfying MCU 113kHz output

I am using an ESP32 to generate a 113 kHz, ~3,5 V output. I then intend to amplify this to a ~50V peak-peak waveform. For that I am trying to use a DC-DC converter based on the LM2577 (to boost from ...
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2answers
127 views

MOSFET 24V high-side switch

I'm trying to control 24V solenoids using logic level inputs at 5V. The following circuit works when replacing both power loops with a single 9V battery, except that the voltage across the gate and ...
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2answers
67 views

Logic level switch controlled via ground (0v)

simulate this circuit – Schematic created using CircuitLab Hello, all. My goal: to convert a ground signal pulse into a +5v signal pulse. My question: How on earth do I do this? Backstory: My ...
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41 views

Connecting signalling lines of the multiple devices with different power sources

I started to develop a simple device and this question arose. I need to make some uC device that will be connected to the PCI-E bus via M.2 socket. And I need this device to be working even during ...
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1answer
24 views

How to make a parallel connection between two components when each has its own voltage?

I have a problem to determine whether or not it is safe to make a connection as picture below. Currently I have a H7EC counter connected to a switch and it has 2.7 V across terminal 1 & 2 on the ...
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59 views

Attiny13 affects USBtiny programmer logic voltage levels

I wanted to port a simple program from an Attiny85 to the cheaper Attiny13. To make sure everything would work properly I started trying to upload a simple blink program to the MCU but could not get ...
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86 views

Using a Non-Inverting Buffer for Level Shifting

I've got a project that involves a 5V Arduino and a Raspberry Pi Zero (3.3V) that need to communicate through a serial interface. The easy solution here would be to connect them through USB, but I'll ...
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50 views

Correct MOSFET for logic level switching

I'm looking to switch a 12 volt 0.5A and 2A load using the raspberry pi's 3.3v GPIO pins. From what I've read a MOSFET is the best fit for this application but I'd like to avoid wasting energy as heat ...
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80 views

Is there a component/method that can take any signal, then increase it to 5 volts no matter how small the signal is?

I was using a logic level MOSFET that should turn on when a voltage other than 0 volts between two points is detected. My problem is that the voltage is at times less than 5 volts and probably won't ...
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296 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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32 views

Compatibility of devices with different voltage thresholds/noise margins/static disciplines

tl;dr included at the bottom. Suppose we have two logical buffers from different logic families, where buffer A drives buffer B. Buffer A has the following voltage thresholds: \$V_{OH}=8\ V\$, \$V_{...
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36 views

NPN BJT NOR gate to drive LED. Base resistance problem

Here's a circuit I'm trying to get working : I have two digital signals (B and C in the diagram) coming from a CD40174 flipflop. I use these to light up two LED's. I also use these as the input for ...
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17 views

Why a CPLD input pin behaves almost like an output pin?

I want my CPLD (a MAX II CPLD, EPM240, see datasheet) to accept an S/PDIF input using an optical receiver with TTL-compatible output. I tested the receiver alone: when giving proper power and optical ...
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2answers
56 views

What happens when both sides of a bi-directional MOSFET logic level shifter try to drive it and how to make sure terrible things don't happen?

I understand the principle of operation of a simple MOSFET logic level shifter like the one described in this question. However, the answer to that question only states what happens when we apply ...
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86 views

Would this circuit interface be a safe interface between full duplex and half-duplex UARTs of different logic levels? [duplicate]

I'm primarily a SW developer who dabbles with electronics. I needs to interface my SoC's HW full-duplex UART with an SDI-12 compliant sensor, without burning either of them and hopefully without ...
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57 views

Logic Level MOSFET Behaving Unexpectedly Driving PWM Signal to PSU

I am trying to control a MeanWell dimmable PSU with an Arduino. Since I do not want to exceed 60% of the output of the MeanWell, I want to use a 0 to 6V PWM signal. I figured a quick and dirty way to ...
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118 views

Connect to LIN bus with logic level shifter as transceiver

Is it good idea to connect my microcontroller to LIN bus with logic level shifter (5 <=> 12 V) instead of factory LIN transceiver (MCP2003, TJA1020, etc.)? As I understand, LIN transceiver just ...
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70 views

logic input that can handle a higher voltage but output a low voltage?

I think some logic IC input can handle a range of lower voltage levels but will output at supply voltage... What is the best way to achieve an input that can handle higher levels but output at a ...
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32 views

CPLD High-Z pin - safe to drive over the high logic level voltage?

I have a CPLD connected to a BUS and an EEPROM. The bus has 3v logic and is 5v tolerant. The CPLD is 3v only. If I configure the CPLD pin to be in the high-z state and the eeprom drives that pin to ...
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235 views

Logic Level Converter for Negative Voltages

Here is logic level converter mostly used for converting signals between 3.3V and 5V. (Other positive levels such as 1.8V are also possible). What if I want to convert from 3.3V to -5V logic (negative!...
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99 views

which kind of design of level shifter suitable for high frequency data transfeing in range of 1MHz? [closed]

A circuit needed to convert 3.3V and 5V logical voltage. However, the issue was that the circuit was supposed to handle very high data transfer at or above 1 MHz and up to 16MHz. I thought of ...
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91 views

Usage of 74LVC1T45 in open-drain case

I want to do one 'universal' or 'multiprotocol'-capable IO block and currently thinking of using 74LVC1T45 level translator to do the communication between two different voltage leveled systems. I ...
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56 views

3.3v input in a 1.8v logic question

In a board design there's a mistake in the voltage level to control a reset pin (Signal RESETB). It should be 1.8v but it is driven by a 3.3v level. The datasheet shows the next info: It looks like ...
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Logic-level transistor not switching

I am trying to use a transistor to drive a lamp from a Raspberry Pi (3B+) and I went after one that can be switched by the 3.3V logic. I found the FQP50N06L to have a max Vgs threshold of 2.5V, so it ...
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438 views

~150 WS2812b LED's with Pi Zero and SN74AHCT125N

I'm planning to control about 150 WS2812b LEDs with my Pi Zero and a 5v 11a power source (PC molex connector). Following this guide: https://www.thegeekpub.com/15990/wiring-ws2812b-addressable-leds-to-...
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83 views

Capacitor to discharge upon switch open

Update Please evaluate this third attempt: This is my first electrical project, so please be gentle with me. I know very little about electronics. I'm building a machine that has a crank that users ...
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Driving a 74HC245 in one direction with 3.3V when Vcc is 5V

I have a 5V device that accepts parallel data in. That data is buffered by a 74HC245 IC (TI datasheet, NXP datasheet) where the Dir pin is hard wired to drive in ...
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58 views

Single chip level shifter from LVCMOS to 12 V

I'm working on a nixie clock based on a STM32L476RG microcontroller and HV5530 chips. The microcontroller uses 3.3 V logic while the HV5530 really needs 12 V logic, which is a pain to implement. There ...
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3answers
577 views

Raspberry Pi with 74HC14 connecting to LED strip (WS2812B)

This might be a stupid question, but I can't seem to figure out how to convert 3.3V to 5V with the 74HC14. I have a power source which can supply 5V (see the power adapter at the left), and use it to ...
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34 views

Output voltage of AT28C64B into HC CMOS IC

I am trying to load the output of a AT28C64B parallel EEPROM into a 74HC194 shift register. The datasheet for the AT28C64B states that the minimum high level output is 2.4V, which I believe is not ...
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1answer
313 views

Switching 12v pilot with 3.3v logic

I have an entry gate pilot operating on 12v. I would like to connect it to my esp8266 (3.3v) to control it over the WiFi. I would like to use 12v power line which I already have. The components which ...
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70 views

Stepping Down Logic Level of a Differential Signal

simulate this circuit – Schematic created using CircuitLab Suppose I have a unipolar, differential 24V signal, and I want to step it down for use with a 5V differential receiver (such as RS-422)...
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781 views

N-Channel Mosfet or NPN transistor for Low Power PWM Application

simulate this circuit – Schematic created using CircuitLab LED: 2.05V @ 350mA 5-6 Ohm Resistor for current regulation Hi, currently designing a circuit that controls a LED using a PWM logic ...

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