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Questions tagged [uln2003]

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Current drawn with uln2003 together with mcp23017 or PCF8575

I’m using ULN2003A for driving 28BYJ-48 on my ESP32. SInce I need many motors I need to multiplex. I’m going to use either MCP23017 or PCF8575. Ive read however that MCP23017 has a maximum current per ...
acroscene's user avatar
  • 179
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0 answers
49 views

PCF8575 weird behaviour

So I designed a PCB in which I used PCF8575 i/o expander in combination with 74HC14 logic inverter and ULN2003A transistors, and my idea was the following: Pull the PCF8575's outputs high and send low ...
k0cka's user avatar
  • 51
1 vote
0 answers
106 views

PCB layout review and controlling ULN2003A

I just finished my PCB layout for a relay board, and I would like to ask for some feedback. I'm a beginner in this so any tips will be appreciated. I also wanted to ask if the 74HC14 is a good pick ...
k0cka's user avatar
  • 51
1 vote
1 answer
71 views

Unusual ULN2003A marking

I bought ULN2003A but I am unsure. The marking seems questionable to me. Rude logo and absence of the vertical bar. I can't find anything about the marking from the manufacturer? Anyone to help me?
courantelectro's user avatar
3 votes
1 answer
256 views

ULN2003 low-side switch electrical characteristics

ULN2003A So I'm currently exploring low side switches. I started off with an NMOS transistor array IC (Open drain), to develop a better understanding I've tried to understand the Darlington transistor ...
Harkirat's user avatar
  • 121
-1 votes
2 answers
258 views

ULN2003 does not distribute power equally to all pins

I'm facing a problem when I try control more than one DC motor with a ULN2003 Darlington array. Issue: When I turn on one output, the motor turns in 4s. When I turn on two outputs, the first motor ...
douce's user avatar
  • 71
2 votes
1 answer
1k views

ESP32 LED driver circuit

Is there anything majorly wrong with the below schematic? I'm still learning and I have followed the datasheet but feel like I'm missing something.
robbrown92's user avatar
0 votes
1 answer
278 views

The reason behind LEDS getting dim (Water level indicator using ULN 2003) [closed]

** Whenever I switch on the circuit, the LEDs glow fully for a second and gets off. After 2-3 seconds they start glowing slowly. What might be the reason for the above?
Rafi Md.'s user avatar
0 votes
1 answer
445 views

ULN2003 relay driver (recurring problem)

There are seven relays on the board and a ULN2003 relay driver to control these relays. The BCM pins to the relay driver are marked in yellow below. BCM pins are IO pins from Jetson Nano Development ...
Enes Orhan's user avatar
0 votes
2 answers
518 views

Connecting switch in parallel to ESP32 output GPIO

I want to make a circuit where an ESP32 or a button should controll a relay. The button receives power from a different PS (LD1117AV33) This is a potential diagram: What would happen if the button ...
Carlos Garcia's user avatar
0 votes
2 answers
784 views

ULN2003 relay driver

I designed a Raspberry Pi shield PCB. There are 6 relays on the board and a ULN2003 relay driver to control these relays. The BCM pins to the relay driver are marked in yellow below. When two relays ...
Enes Orhan's user avatar
0 votes
1 answer
1k views

Why are my motors not getting enough power?

I am a newbie electrical engineering hobbyist who is trying to get four 28BYJ-48 stepper motors to turn for a split flap display project. I managed to get each motor working perfectly well ...
KidWithComputer's user avatar
0 votes
1 answer
486 views

How to fix this ULN2003 circuit?

I am trying to understand the working of the ULN2003, but I can't run this circuit properly. Please help me understand why this is not working.
KAMRAN HASSAN's user avatar
1 vote
2 answers
994 views

Can I use a ULN2003A IC as many transistor switches?

I want to make home automation using Arduino. Instead of relay modules, I prepare my own relay module using relays and transistor switches, in between the Arduino and relays. I want to make many ...
Nifty 17's user avatar
1 vote
1 answer
455 views

Is it must to have freewheeling diodes for ULN200x when used with dc motor?

I need to eliminate the MOSFET drive circuit from my PCB by replacing uln2004 or uln2803, should I still keep the back EMF diode across the dc motor? motor supply 5V current 70mA
oppo's user avatar
  • 547
0 votes
2 answers
173 views

Convert 8 bit Parallel output from ULN2003 to serial without any Microcontroller

I am hobbyist only with some basic idea about electronics.. I am trying to measure rooftop watertank water level and to display it on a small led bargraph. So by googling I thought about to proceed ...
Sandeep Thomas's user avatar
0 votes
2 answers
1k views

Requirement of ULN2003 IC in circuit

I'm just a hobbyist and actually from software side. Trying to build a simple water level indicator and found the following circuit using the IC ULN2003. But due to my very less knowledge I'm not ...
Sandeep Thomas's user avatar
0 votes
1 answer
428 views

Can we use ULN2003A to power up another module

I have one requirement wherein, I need to power up one of the modules occasionally. I do not have relay in my controller board, but I have ULN2003A in my board. The module consumes around 400mA. So ...
Rajesh's user avatar
  • 229
0 votes
1 answer
303 views

Switching buzzer on and off with two transistors

I want to make a simple water level indicator with tank full alarm as shown in the diagram. What I want to achieve is, when the tank is full to 100% and water is still flowing through the inlet pipe (...
Vinodvnmy's user avatar
0 votes
2 answers
445 views

Shorting of VCC & GND for short duration of time

I have used ULN2003A for my custom board. While checking "continuity" between VCC and GND there is a continuity for a short duration of time(less than a second), it comes at a random time. I have ...
MightyBeard007's user avatar
0 votes
1 answer
375 views

How to increase ON Time of a Relay?

I am trying to increase the ON time of a Relay. The Relay is turned ON from ULQ2003 by a 1 Sec ground pulse on its OUT1 Pin. I am trying to increase it to approximately 3 Sec. The accuracy of pulse ...
alt-rose's user avatar
  • 1,479
2 votes
3 answers
774 views

ULQ2003 not driving a Relay properly

I am driving a 9V DC (5 PINS) Relay from darlington array ULQ2003. The ULQ2003 COM pin is connected to 9V power supply while the Relay coil is connected to +12V supply. The Ground of both are ...
alt-rose's user avatar
  • 1,479
-1 votes
1 answer
738 views

Multiplexing common anode 7 segments using only 2 shift register, darlington array, and transistor

I'm trying to multiplex up to 8 digit common anode 7 segment display using only 2 shift registers chained together in series driven by arduino. So it would need only 3 pins (trying to save up pins ...
gema's user avatar
  • 3
1 vote
2 answers
509 views

ULN 2003 open collector

I have searched for troubleshooting the ULN and did not find any solution. I use a ULN chip in a motor inverter for controlling precharge relay and main relay. The problem is when the motor inverter ...
Johannes's user avatar
6 votes
2 answers
3k views

Water level indicator using ULN2803

i made an water level indicator using IC: ULN2803 Refer: Easiest water level indicator It works well when used on glass of water, but when connect to my rooftop tank all the leds slowly diminishes ...
Alex Robbin's user avatar
1 vote
2 answers
1k views

ULN2003 Saturation Voltage help

I'm busy designed a PCB that will use a Raspberry Pi's GPIOs to to drive several optoisolators. Additionally I'm also interfacing with an IO module that works with HIGH > 1V. Because of the number ...
riaanc.'s user avatar
  • 13
2 votes
3 answers
2k views

Controlling Solenoid Valves with ULN2003A, Inrush Current, Arduino

I want to control a total of five solenoid valves with my Arduino. The solenoid walves operate at 12 volts and have a power consumption of 5 watts per solenoid valve, which equals a current of roughly ...
Chris1309's user avatar
1 vote
2 answers
569 views

ULN2003 current flow through non enabled pins

Edit: solution found There was some amount of flux residue remaining on the board from when I soldered it. My meter didn't beep in continuity mode, but it did register some resistance, which I didn't ...
MKUltra's user avatar
  • 147
0 votes
1 answer
116 views

Controling where sound goes (darlington array)

source of sound (dealing with multiple sources) and six speakers. I want to control to which the sound goes. The system has a DC offset with both sides of the wave within positive range Question is ...
Tomas's user avatar
  • 141
1 vote
2 answers
820 views

Driving solenoid valve using LM358 as comparator and ULN2003

I'm trying to drive a 12V DC solenoid Valve with following diagram. In 1st block the PC input is compared with 2.2V and its output goes to block2 and ULN2003 for driving the valve. The 2nd block is a ...
Mehran's user avatar
  • 237
0 votes
4 answers
892 views

uln2003a: Switching ground of device works, however, optional USB function of device doesn't work correctly

I use the uln2003a to switch a device (with use of a MCU) that is capable doing several things, like fm-radio, bluetooth, playing MP3's etc. It also provides an USB ...
Codebeat's user avatar
  • 1,367
0 votes
1 answer
957 views

Startup Buzzer Sound

I have made a button box, using an Arduino mini pro, which includes LEDs and buzzers. I am using a shift register (74HC595) with a ULN2003 (to use 12v on the LEDs) to decode the SPI. See the top ...
Fed's user avatar
  • 435
1 vote
1 answer
2k views

MCU to switch single coil latching relay not working (attempting array with common gnd)

I have several single coil latching relays, (low rep points so not hyperlinking), mouser.com/ds/2/212/KEM_R7002_EC2_EE2-540906.pdf (EC2-5SNU). I am trying to control them by an MCU; connected ...
Orbitronics's user avatar
0 votes
1 answer
775 views

One stepper motor of two getting really hot

I'm using two 28BYG-48 stepper motors rated for 12V. These are unipolar motors with 5 wires. 1 Common wire and 4 wires to control the 2 phases. The motor that is getting hot has around 76-77ohm the ...
Loïc Faure-Lacroix's user avatar
2 votes
3 answers
7k views

Explanation how uln2003a works

This is a schematic for the an internal input/output pins of an uln2003a and other such array transistor. From what I understand, when no voltage is present on the first transistor, the current will ...
Loïc Faure-Lacroix's user avatar
0 votes
2 answers
8k views

Easiest way to check if uln2003a is working

Ok, here's the schematic I'm trying to use to test if my uln2003a chip is working. While checking the pinout with my multimeter, I couldn't find that pin out1 was connected in some ways to the com pin....
Loïc Faure-Lacroix's user avatar
1 vote
1 answer
2k views

Multiple Voltages for ULN2003

I am using a ULN2003 to power lamps and LEDs, and controlling them via 5v TTL. I have some LEDs can be driven by 5v, and some lamps which require 12v. Using the same ULN2003, can I have some ...
Fed's user avatar
  • 435
1 vote
1 answer
485 views

Stepper motor control - full step not working

I am using a ULN2003 to control a unipolar stepper motor from my PIC18F45K20. When I only connect one 12 V power cable (Red), the stepper motor works in full step, however, when I connect the other 12 ...
Matthias's user avatar
1 vote
3 answers
8k views

What is the purpose of 9th pin in ULN2003

Whenever I need to use relays with Microcontroller, I use ULN2003. I connect the GPIO from MCU to the input pin of ULN. Connect 8th pin of ULN to GND and take ...
S Andrew's user avatar
  • 621