LM3914 LED 1 DOT Mode problem...

Thread Starter

Clomifuge

Joined Jan 16, 2022
36
Hi all and happy new year.

I know the this question was posted a numerous time but I never seen a reply, if yes very sorry.

I have a LM3914 in simple Vu-Meter, the Voltage PSU is 5VDC with a BARLED 10 LED Bloc in DOT mode the LED 1 always stay on.

I discover that the problem seem to be disappear a little bit with a another 10LED BAR Bloc (KINGBRIGHT) but the problem is always here, lowest brightness but stay ON.

Thanks by advance.

Clomi
 

Ian0

Joined Aug 7, 2020
4,821
Hi all and happy new year.

I know the this question was posted a numerous time but I never seen a reply, if yes very sorry.

I have a LM3914 in simple Vu-Meter, the Voltage PSU is 5VDC with a BARLED 10 LED Bloc in DOT mode the LED 1 always stay on.

I discover that the problem seem to be disappear a little bit with a another 10LED BAR Bloc (KINGBRIGHT) but the problem is always here, lowest brightness but stay ON.

Thanks by advance.

Clomi
To ask the obvious question - what is the voltage on pin 5?
 

MrChips

Joined Oct 2, 2009
25,919
Do you want to use one section of the display or all three sections?

For one section, just use the one you want.
If you want to use it as a single 30-dot display it might be better to use a different solution such as with an MCU.
 

MrChips

Joined Oct 2, 2009
25,919
Sorry I don't understand your question ! I have this BARLED Bloc (30LED) and I want to do a VU-Meter with the LM3914/15 and this Bloc, I don't start to realize the project, I just to want how can do that with this special 30 LEDS bloc.

Thanks and sorry for my misunderstanding
In that case, forget the LM3914 and use a microcontroller unit (MCU), Arduino, for example.
 

MrChips

Joined Oct 2, 2009
25,919
You can cascade (chain) three LM3914/5 followed with ten 3-line to 1-line multiplexers. Then add the multiplexing hardware. This brings you over ten ICs.

You can do it with one chip.
 

Thread Starter

Clomifuge

Joined Jan 16, 2022
36
I have seen this behavior using the LM3914. It seems to happen when using very sensitive LEDs. The simple solution is a 4.7K or a 10K resistor in parallel with LED #1.
Hi and thanks for your reply, I will test it and I let you know.


Best and thanks again
 

Thread Starter

Clomifuge

Joined Jan 16, 2022
36
Hi and thanks for your reply, I will test it and I let you know.


Best and thanks again
Hi

I tested with a 10k or 4?7K resistor in parallel with the LED 1 and the problem still here, the resistor attenuated the brightness but not solve the problem...:( sorry and thanks I think this is a LED problem.
 
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