Questions tagged [uln2803]

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43 views

ULN2003/ULN2803 for Switching Application

I'm prototyping a board which will drive a control module. I'm not an electrical engineer by trade but I have tried to learn as much as I can. The board is intended to interface with 8 logic lines, ...
3
votes
3answers
589 views

ULN2803 not working like I expect, or at all

I am a total electronics noob trying to build a simple circuit for a jukebox that I'm making using a Raspberry Pi and an old jukebox wallbox. I'm a computer systems engineer by trade. And it's my ...
0
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0answers
44 views

ULN2803 switch off

I have a ULN2803 that drives a higher current H-Bridge but the issue is the ULN2803 is inverting the output. I was thinking of switching the ULN2803 off until the micro-controller is ready to take ...
1
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1answer
78 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
0
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2answers
50 views

ULN2803 behavior when its output is not connected to any load in this circuit?

I'm studying the a circuit that is using a driver ULN2803 datashet. The driver is needed for external loads as LEDs when a pin is writing. The situation that I would like to talk about is when the pin ...
1
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1answer
246 views

Led Matrix multiplexing: sinking/sourcing current + LED brightness

I am trying to make an 8x8 LED matrix (actually a bigger one, but for now it would be easier to discuss this more simplified version) and I have gotten too confused about a few things concerning the ...
0
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1answer
107 views

Can there be a voltage spike from ULN2803 to MCP23017?

I would like to ensure I have designed my circuit to operate safely. I am trying to control a 12V electric lock using Raspberry Pi. I have connected my SCL and SDA to MCP23017 and the output of ...
0
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1answer
105 views

ULN 2803A Relay Driver Circuit

I am building a basic relay driver circuit using ULN2803A. I have attached the basic circuit diagram, i would like to know if i am missing anything. I am Planning to use it with HLKPM01 5V Power ...
0
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1answer
81 views

Driving ULN2064 with 74HC595 for 12V motor loads

I've made a circuit with ( Arduino + 74HC595 + ULN2803 ) to drive 20 hobby motors using 12V 10A Supply. Initially It Looks Good, But when i started running one motor, Motor running too slowly and ...
0
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0answers
564 views

Deciding between ULN2804 or ULN2803 with 74HC595

I'm making a circuit with Arduino + 74HC595 + (ULN2804 / ULN2803) to drive a few 12 V Motors. I'm trying to decide whether to use the ULN2804 or ULN2804. On testing, performance of both is fine, ...
2
votes
1answer
3k views

How to calculate current limiter resistors for ULN2803 and Relay?

I'm designing a digital I/O, and for the outputs I have ULN2803 and relays. I have the schematic below. The coil current of relay is 16.7mA, ULN2803's max input current is 1.35mA and output current ...
0
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1answer
310 views

Voltage drop on relay coil while driving relay using Darlington Arrays

I am using Wemos D1 mini and trying to use ULN2083A Darlington Arrays to drive SRD-05VDC-SL-C relay. The relay does work properly when the circuit is connected as attached schematic. The Darlington ...
0
votes
1answer
288 views

LED ULN2803 thermal / heatsink questions

I'm intending to use LEDs of 5mm, which have a max forward current rate at 30 mA, or a value of 100 mA, with 10% 1 kHz duty cycle, in a circuit like the one below except some changes: STM32F103C8T6 ...