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Questions tagged [uln2003]

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5
votes
2answers
564 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
vote
2answers
50 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
223 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
98 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
44 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
vote
2answers
199 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
votes
4answers
173 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
324 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
347 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
352 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
vote
3answers
2k 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
2k 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
534 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
292 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 ...
-1
votes
3answers
2k 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 ...