1. M

    Controlling high power LED with transistor and Arduino

    Hello, I'm doing a small project and I'm stuck. I want to control brightness of 90v 185mA LED strip with my Arduino Uno. I used bd941 transistor in series with LED strip and I'm sending signal form arduino PWM digital pin to 100om resistor and then to transistor base.(in datasheets for...
  2. beic

    i2c Pull-up resistors for multiple chips

    Hi there, I wish to connect multiple i2c chips together on the same PCB board, these chips are DS1307, DS1621 and AT24C256. My question is, do I need to put 6 x 4.7k pull-up resistor (2 resistor / chip) or 2 x would be Ok for those three chips as shared? Also what will happen if I would...
  3. D

    Measure voltage on 12v SLA battery with arduino

    I've been reading how to measure voltage using an arduino uno (cheap knock off) analog pin. I have a project that will be powered by a 12v SLA battery. I do have a 7805 to get 5v to the arduino and a few components. I would like to turn on a red LED when the voltage gets down around 11v as...
  4. farzad latifeh

    INA219 Sensor faulty output

    I made a device to track battery discharge pattern, it works with Arduino and INA219 Sensor, as you can see in the schematic, the system is wired somehow with a common GND, when I put one battery in the device, it works as I expected with 3.9 Ohm resistor in the path, but when I add second and...
  5. E

    how to properly make a charging circuit -- 2s 7.4V to 5V 2A

    I have 2 18650 li-ion cells, each at 3.7v (in case you don't see the pictures, they are available here : https://raspberrypi.stackexchange.com/posts/121847 ) and this bay with this white connector I saw on youtube that depending on the length of the cell, we can know whether they have...
  6. B

    l298N motor driver one terminal is not working.

    Hello guys, Im beginner in this field, so pls be patient with me. So here's my question, Why is one of the terminal (they call it motor1 ) of l298n not working but the other side(the motor 2 ) is working. By the why I am using 2 linear actuator same 12v and my power supply is 12v and i did the...
  7. T

    Pressure sensor in flowmeter is accurate but not consistent

    Hi All, I have a ultra low differential pressure sensor in a flow meter configuration(Venturi meter). https://www.te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Data+Sheet%7FSM9000%7FA1%7Fpdf%7FEnglish%7FENG_DS_SM9000_A1.pdf%7FCAT-BLPS0062 Through help from the members...
  8. firashelou

    How to stop a timer delay using millis() from executing with NRF24L01 Network (Arduino)

    Hello, what i have in my circuit is 2 push buttons, the first for starting a timer of 3 seconds which then when the timer is done it sends a 1 to the NRF24L01 which turn a relay on for a specific time which is 3 seconds then turn it off by sending 0 to NRF24L01. The second button is reset button...
  9. V

    Arduino i2c communication hangs while running motor

    I have a Arduino uno board connected with PCA9698(I/O expander) through i2c communication. Controlling if input and output were working correctly. The data pins from the PCA9698 is connected to the 24v DC motor driver(BTS7960) and also sensors(PROXIMITY sensors). While reading the sensors there...
  10. T

    Differential Pressure Sensor zero error constantly moving

    Hi All, not sure if this should be in the test or the sensor section, apologies if I have mistakenly placed it here. I am currently trying to calibrate this Pressure Sensor (...
  11. M

    voltage subtractor

    i'm working on a arduino based BMS which have to measure voltage from a multicell battery which is connected in series. i can measure the voltage of the cells by individually grounding them. But what i want to achieve is to measure single cell battery voltage when they are connected in series. I...
  12. B

    AC Coupling Arduino PWM Output Over varying Frequencies

    The load on the output is 100ohms. The frequency will vary through the full range of the arduino. My simetrix simulations shows it should work using a 100uF capacitor biased by a 1Mega ohm resistor, but in theory it doesnt. If someone knows the values of the components to use or another method...
  13. R

    Arduino guitar pedal help

    Hi! I've been working on a school project, that is a guitar pedal (effects) using an arduino board. I've been using the EasyEDA site for designing the schematic. I would like to ask a more skilled/experienced person to go over my design and look for any flaws or mistakes. Any tips about it...
  14. Dimbel36

    IGBT Gate Driver Selection

    Hello, I'm designing a resistive load bank. Currently, I am designing the switch that will be controlled by a control signal via Arduino uno rev 3. The bidirectional switch is composed of two back-to-back igbts connected by their emitters with anti-parallel diodes. (Due to cost, there are two...
  15. I

    TTGO V1 no GPS signal

    Hey Folks, I am encountering the following problem. I have a TTGo board V1 and i tried compiling this code on it #include <TinyGPS++.h> #include <axp20x.h> TinyGPSPlus gps; HardwareSerial GPS(1); AXP20X_Class axp; void setup() { Serial.begin(115200); Wire.begin(21, 22)...
  16. lefterisgar

    DIY Arduino-powered 12V UPS suggestions | HELP NEEDED!

    Firstly my wishes to whoever reading this piece of text, have a nice year and I hope that everyone is doing fine in this current pandemic and I think this is going to be a piece of the past very soon... I'm also sorry for two things regarding this thread: I'm not a fluent English speaker. I...
  17. B

    Automated watering system

    I was wondering if someone could help and guide me in a little project that I am working on. I am making an automated watering system for my wife. I can't seem to wrap my head around the 'C' script/code. This is what I want to happen. Using an LDR I wish to determine weather it is day or...
  18. T

    Diode usage in SPI modules

    Hi All, Hoping that someone can put me out of my misery. I have been searching the internet for the past 5days for an answer to this question and feel like I am starting to lose my mind. Can anyone explain why the attached schematic has a 1N4148 on each of the SDI_5V, SCLK_5V and CS_5V lines...
  19. B

    Arduino with ps2 for 2-motor control

    I am trying to program a UNO to control a robot to move forward and back using a ps2 with joystick. I want to control the speed by moving the js on x-axis and direction by moving js on y axis. The foll. code works but without js controls. Now want to include js controls. Any help appreciated...
  20. zazas321

    How does LoRa work in ESP32

    Hey. I want to try to make low power device based on ESP32 to send readings to the server. I have come across this tutorial that describes how to get lora working on ESP32: https://randomnerdtutorials.com/esp32-lora-sensor-web-server/ Lora reicever function: void getLoRaData() {...
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