lm 3915 vu meter problem.

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Jump to Latest
Spiny

Spiny

Member
Joined 2008
allthingsspiny.co.uk
The diagram with the diode is an input for audio. The audio earth goes to ground (-ve).
Connect the Audio signal to the in(put). Connect the end of the 1K resistor to pin 5 on the LM3915.

With a bargraph setting (pin 9 to positive) this will display the signal. Speed depends on the capacitor value.

Attempt at a video (avi) of the VU meter

May be best to right click and download the avi file I think, does not work too well in Firefox with VLC for me.
@ 7mb

alan
 
Last edited:
G

gmphadte

Member
Joined 2003
lukutis said:
Mooly, you have the patience of a saint.
aggree. No one else survived my questions that long.. I know that i should try to do it by myself and stuff but believe me im so bad, most things i try to do by myself 99% i fail. The god didint give me enough brains and my logical thinking is also very very bad..
Click to expand...

Everybody is special.

You have to be systematic while doing such an adventure.

And you have to check each net and complete all the connections at each point(net) without going to the other net. First check pin 1 is correct.

e.g. pin 8 connects to R1 and R2...done it then the net is connected. Pin8 issue is over.

Gajanan Phadte
 
Spiny

Spiny

Member
Joined 2008
allthingsspiny.co.uk
lukutis said:
in that circuit Spiny showed me. where i need diode , 2 resistors and capactior. My input is pin 5 so i dont get it.. I connect that diode to pin 5(input) and that resistor 1K ohms also gues to pin 5? do i get it right?
Click to expand...

the Audio input goes to the diode, the resistor to Pin 5
the audio ground goes to negative

To test Connect the diode input to +ve this puts 9v on the input. All the leds should light if pin 9 is connected to positive (bar graph mode)
 
Spiny

Spiny

Member
Joined 2008
allthingsspiny.co.uk
Here is the LM wired up to test.
I suggest you put a led and resistor (1k-5K resistor will do) from positive to negative as a power on indicator, this will show if the battery is connected and if it has some power in it.

Check the IC is the right way round. Pin 1 is the end with a small cut out/ dent usually semicircular. some have a dot molded by pin 1

Do connect Pin 9 to positive.

alan
Ive used a 47K to stop the blue led used blinding the camera :)
 

Attachments

  • LM_meter2.jpg
    LM_meter2.jpg
    146.2 KB · Views: 33
Spiny

Spiny

Member
Joined 2008
allthingsspiny.co.uk
Can you check the resistor from Pin7 to pin 8. it should be Brown Black Red + Gold or silver. your picture suggests Orange as the 3rd band
If its orange then its a 10K not 1K
the original Gif suggests 1.2 K thats Brown Red Red + Gold/silver
(Brown Red Orange is 12K)

the value of the resistor from the diode to negative should be around 100K , the one to pin 5 @ 1K
I can not read the values from the photo I'm afraid

Is there a wire from pin 4 to negative? there appears to be one from pin 2 to negative.

To stop confusion have Positive only at the top of the breadboard and Negative only at the bottom. Do not use the extra power rails. Put a power light from + to - to tell you the battery is connected.
 
Last edited:
L

lukutis

Member
Joined 2015
Spiny
Resistor between pin 7 to pin 8 is 1k
resistor from diode to negative is 100k and other resistor from diode is 1k. capacitor im using is 1uf and capacitor positive connects diode cathode and negative to ground :/ When i connect my audio to pin 5 everything works but only 6 leds blink... when i connect to diode all the leds immiadetly turns off
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Top Bottom