Questions tagged [uln2803]
21 questions
3
votes
3 answers
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 first time asking a question on SE, So please go…
Scot Kreienkamp
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2
votes
4 answers
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, where each may be pulled high to 30V which comes…
Res
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- 2
2
votes
1 answer
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 is 500mA/per channel used.
How should I calculate…
Teoman Açıkgöz
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1
vote
3 answers
I want to obtain 30 relay outputs using an optocoupler and ULN2803
I am designing a PLC board using ESP32. This board will contain 30 relays. I want to design the protection circuit for these relays as shown in the upper left corner of the photo. Due to the high number of relays, I need to use ULN2803 and PS2801-04…
Mehmet Emin ARSLAN
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1
vote
1 answer
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
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1
vote
1 answer
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 current I need to source or sink as well as the…
tsambou
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0
votes
1 answer
Correct use of a ULN2803A
Did I wire up correctly this ULN2803A?
I am trying to use it to power an RGB LED Common Anode strip ith a length between 50 cm and 1 meter, and a 24 relay with an Arduino Mega 2560
Thanks in advance
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Luismm2311
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0
votes
0 answers
Unexpected output from ULN2803AC when input is given manually
I am working on a single-digit seven-segment module. The module can take input as BCD when the ULN2803 connected to the CD4511 is grounded via the N-channel MOSFET. The other MOSFET is off in that case. Or it can toggle each segment individually by…
Hesham Hany
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0
votes
0 answers
Do entire IC labels need to match? ULN2803A replacement
I burned out an IC on my OmniLogic pool controller and am looking to try to replace it. I've never attempted repairs with ICs before, and don't know much about them. The chip is a TI 1CZRL34 ULN2803A G4 (picture included below). Would any ULN2803A…
0
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1 answer
0
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1 answer
No output signal with ULN2803 on Proteus
I'm using an ULN2803 to amplify a voltage signal from an Arduino, but the output is 0 V even though the input is 5 V. I've tried multiple simple circuits to test it, but it just doesn't seem to work. I don't know if it's a Proteus problem or…
Seyl
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0
votes
0 answers
Problems with ULN2803
I have a circuit with a ULN2803. The output pins of the ULN2803 are connected to 8 LEDs.
The problem is that irrespective of input voltage (either high or low) all output LEDs are glowing for a fraction of a second WHEN POWERING ON THE…
0
votes
0 answers
ULN2803A Relay Driving Circuit from ESP-12E through PCF8574
I am designing a circuit which will drive 4 relays & 2 LEDs from 4 push buttons(for each relay) with ESP-12E via (I2C) IO expander PCF8574 as I need more IO's than what are usable(stable) on ESP-12E. I'm using ULN2803A as a relay driver circuit.…
saurabh kandalkar
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0
votes
0 answers
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 over but I'm not sure how to go about it.
For…
2A-66-42
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0
votes
2 answers
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 is reading. As the GPIO interface is MCP23s17…
Suvi_Eu
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