lm 3915 vu meter problem.

[lukutis]

also i wired up another led as someone show to see if there is a power in my circuit. and led is glowing showing that there is power

 

[lukutis]

and im using 1B4148 diode if that makes any difference. i can take any photos but i dont think so that would help cuz its really hard to see connections from photo

 

[lukutis]

and i didint connect pin 4 to negative. but if pin 2 is connected to pin 4 i guess pin 4 is automatically connected to ground

 

[turk 182]

shorted capacitor?(without a meter it's impossible to tell)
inverse polarity on the diode?(ditto)
just because a part looks physically ok doesn't mean it is.
resistors can be open or off tolerance but look ok.
so without a meter how can you be sure the parts you added including the diode are ok (and the right way around)

 

[lukutis]

yeah :/ probably i cant
http://www.megaomas.lt/get.image.php?key=image_1&id=4258&thumb=0 this would one work?

 

[turk 182]

like a charm! how much?

 

[Spiny]

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

Its working - Reverse the diode and the leds should blink.
Try some different cap values like 0.5uf (0.47 will be preferred value) or 0.047uf (47nf) once it is working with the diode, a 1n4148 is fine.

To check all are working connect +ve to Pin 5 (or the diode)

I suspect the reason the last few are not working is a peculiarity of the breadboard. This type has the power lines split in the middle, you need to connect across the gap. See attachment.

Sorry I missed that earlier. With a meter you can check continuity. Handy gadgets, like most folks here I have several mainly cheap ones and one expensive and calibrated one to check the others against.
see this which I think is the type you have.
electronics introduction to breadboards

alan

 

[lukutis]

its pretty cheap turk. like 10 euro
tryed reversing the diode and after i touched the my audio wire to diode i could hear cracking sounds i dont think so thats supposed to happen.
Tryed to connect those power lines together but still nothing ;/ Hmmm strange.. i guess if i connect my audio to the diode something should happen no matter 1uf or 0,5uf.. but now nothing happens at all.. not even first led blinking. i might missed some connections but everyyything seems okay without multimeter

 

[lukutis]

i noticed one thing if that would help that if i take out that resistor 100k ohms from diode to negative all leds starts to glow slowly 1 by one. but after i connect a that resistor as i said.. everything turns off.

 

[Spiny]

You need to connect the power lines, removing the 100K resistor will cause the capacitor to hold its voltage - and the display is showing the voltage climbing.

What are you using for audio? as it is this is suitable for loudspeaker output - and it would be loud! to light all the LEDs

Check the 100K really is should be brown black yellow for the bands on a 4 band resistor (with silver/gold as the finaly band) the image is not good enough to read the bands so can not tell.

alan

 

[lukutis]

haha found out that i mixed two resistors... that one 100K which was supposed to go to negative went to pin 5... Changed now how it should be but still nothing :d yes its 100k. brown black black orange

 

[turk 182]

if you had a meter you'd probably measure that resistor and discover it's 10 ohms (what looks like orange is actually gold (5%)or possibly faded red(2%))100k should be brown, black, yellow the 4th band is tolerance
your shorting your signal to ground

 

[lukutis]

i have resistors package of resistors and even on the package it says that this is 100k . its really orange . brown black black orange

 

[turk 182]

ok what color is the tolerance band?(from what your describing this resistor has 5 color bands correct?)

can you show me the pack label (would not be the first time i've heard of mislabeled parts)

 

[lukutis]

http://i.imgur.com/qy8nzgt.jpg
yes its abit confusing im not sure from which side should i start counting if i count from bottom it looks like 100K but if i count from top...

 

[lukutis]

sry i dont have a decent camera... http://i.imgur.com/J8C6ksX.jpg
here u can see the orange a little bit better

 

[Spiny]

sry i dont have a decent camera... http://i.imgur.com/J8C6ksX.jpg
here u can see the orange a little bit better

thats 100K its a 5 band one and Brown is 1%
1 0 0 * 1000 (Brown black black Orange) and brown for 1%
the larger gap should be Orange<> brown

the 1K should be Brown black black Brown (brown 1%)