Awesome LED VU meter: Any idea?

[transistor495]

Hello All,

Recently I'm playing a bit on LED VU meter circuits and trying to make the best one

I've already built the normal circuit using LM3915N, however,

Do anyone of you experts have an idea on this cool thing is the question:-

Really impressed on that and that's what actually in my mind since so long(yep, that floating peaks..you got right?

 

[duffy]

Says the video is "blocked".

 

[dr peppers]

I havent seen tombstone leds for a while, very 70's.

The ic in the vid could be a pic micro ( with18 pins maybe an 16f88), however I think holtek do a chip thats a mono VU with peak hold.

How about a nixie vu meter, I have a similar tube in a clock I made its argon filled so lights up sort of a UV colour.

https://www.youtube.com/watch?v=aFefRYPvqoY&feature=related

 

[bountyhunter]

Hello All,

Recently I'm playing a bit on LED VU meter circuits and trying to make the best one

I've already built the normal circuit using LM3915N, however,

Do anyone of you experts have an idea on this cool thing is the question:-

Really impressed on that and that's what actually in my mind since so long(yep, that floating peaks..you got right?

That looks like a professional type VU that has "peak hold" on it. Not the cheap stuff.

 

[transistor495]

Yeah, I can understand that its not a cheap stuff because it outputs a very professional grade display like something we could see in a costlier PA systems and all, but I thought there is a possibility of a single chip IC with LED driver/peak hold for that -not much popular though.

At first I thought it could be a PIC micro stuff with programmed output.

However, do anybody think that AN6870N is the engine here(I think it used in old electronics FL displays)..could be an obsolete chip

Could be possible with Sanyo LB1412 also, but I don't think that is the stuff used here.

My search didn't return anything else. Dr peppers, I like that Nixie display!

 

[ronsimpson]

You could use two LM3915s. One with a averaging front end and the other with a peak detector. One set for line and the other set for dot mode.

 

[wkrug]

You could use two LM3915s. One with a averaging front end and the other with a peak detector. One set for line and the other set for dot mode.

Or use one and switch with a analouge switch between the 2 modes and levels.

 

[ronsimpson]

That display has 16 LEDs so it is not a LM3915.

 

[dr peppers]

Older pa equipment used lm3914's, the last led (high end) can be connected to the dot/bar mode pin, so that when the display goes right to the end it goes to dot mode, showing that the display is off the scale.

You could use 2 lm3914's, good idea, it would not look like the video however, in the vid the peak led stays on for a second then resets, 2 lm3914s would give 2 simultaneous displays, one a bar and the other a dot, the dot would go up to the peak signal level then creep back down instead of resetting, you'd filter the bar with a faster response and the dot with a very slow one.

 

[transistor495]

Okay, guys thanks for all your thoughts on this

At last I found what it actually is, it's simply a PIC16F88 driven stuff(Dr peppers guessed it), the whole stuff is here in the link:

https://s-o.webnode.cz/vu-metr/

I'm yet to find what language the site is, and output video same like in the OP is here:

https://www.youtube.com/watch?v=wPiLTrPExNE

I should try this.

 

[transistor495]

Yeah, I understood using the two LM3914/15 in parallel mode, but I doubt with the hold/creep down 'dot' mode operation because, the 'hold' should stay for a second or so and the 'creep down' should be very fast, don't think this double configuration is possible with a single LM3914/15. The 'bar' mode should work fine anyway.

Means if the peak holds for a second, then the each downward creeping LED's will take the same 1 sec.

Nice thoughts anyway, I appreciate it.

 

[Inquisitive]

The ".cz" indicates Czech Republic. How is are your Czech language skills?.

 

[transistor495]

The ".cz" indicates Czech Republic. How is are your Czech language skills?.

Yeah, currently going on with online translator:

https://www.translation-services-usa.com/czech.php

Well, not bad

 

[transistor495]

Eh?..trying to get a USB PIC Programmer this month itself and start executing this cool stuff...

Will post the results.

Cheers.

 

[dr peppers]

I reccomend a pickit 2 or 3.

 

[ronsimpson]

I have made LCD meters that look like this.
https://www.youtube.com/watch?v=aFfTp0nhEs0
Also meters that look like this.
https://www.youtube.com/watch?v=4pvstaKy4MI&feature=related
Here is a very interesting VU meter. See the video at the end.
https://www.sparkfun.com/tutorials/120

 

[dr peppers]

Like the spectro analyser mr simpson, does it use fft, or are the channel filters hardware?

Also like the way the characters fade in and out using partial graphics on the vu, professional touch.

 

[ronsimpson]

I did not do these projects. I have done similar things.
The fade in / out is because the LCD is slow to respond. It is not a feature.

 

[dr peppers]

I've never done a vu, but I did write some code to display the lamba signal from a exahust gas sensor and I had a vertical rather than horizontal bargraph so that I could show a trend, it worked in the end but I remember having trouble getting the custom character generator to work in the display.
Theres some nice examples where peeps have done this sort of thing with a glcd, never used one of those yet.

 

[ronsimpson]

I have done bargraphs on character LDCs (16x4 or 16x2). In horizontal mode I made 128 position meters. Using 8 custom characters.

I am playing with GLCDs. Some take each byte as 8 dots vertically. If you want 8 dots horizontally then there is much software overhead.
Some GLCDs use one byte/ pixel. Some use 3 bytes / pixel. Some use 1.5 bytes / pixel. The last example in post #16 requires about 100 bytes to update the meter.