Questions tagged [uln2003]

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1answer
51 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 ...
0
votes
1answer
56 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 (...
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2answers
60 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 ...
0
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1answer
93 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 ...
2
votes
3answers
319 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 ...
-1
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1answer
168 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 ...
1
vote
2answers
148 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 ...
6
votes
2answers
1k 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 ...
1
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2answers
157 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 ...
2
votes
3answers
536 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 ...
1
vote
2answers
196 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 ...
0
votes
1answer
45 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 ...
1
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2answers
340 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 ...
0
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4answers
352 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 ...
0
votes
1answer
514 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 ...
1
vote
1answer
642 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 ...
0
votes
1answer
474 views

One stepper motor of two getting really hot

I'm using two stepper motor 28BYG-48 rated for 12V. Those are unipolar motor with 5 wires. 1 Common wire and 4 wire to control the 2 phases. The motor that is getting hot has around 76-77ohm the ...
1
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3answers
4k 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 ...
0
votes
2answers
3k 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....
1
vote
1answer
1k 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 ...
0
votes
1answer
352 views

Stepper Motor Control - Full Step not working

Good day, I am using an ULN2003 to control a unipolar stepper motor from my PIC18F45K20. When I only connect the one 12V power cable (Red) the stepper motor works in full step. However, when I ...
0
votes
3answers
4k 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 ...