LED VU-meter

[johnheath]

Hi all...

Question: Is there a good way to build such a VU-meter from LED's  without op-amps and if so how?

Regards

John

http://www.eeweb.com/project/circuit_projects/10-led-vu-meter-project-by-lm3915-and-lm3241

 

[Rochey]

Microcontroller ADC and doing a software comparison.

 

[s2udio]

Been using these just lately...cant be arsed DIYing them anymore
Personally think they are the dogs bees.
Good price too
http://www.barmeter.com/en/viewproduct.asp?ID=197&XiajiID=1
Very fast with switchable modes.
Purchased thru their Ebay store,which took one week to deliver to the UK

 

[johnheath]

Mmm... ok, nothing for me then =)

I was thinking it could be done with a resistive circuit for each LED to be engaged like a ... using say 12vdc from a tube heater or utility circuit?


Regards

/john

 

[johnheath]

They look nice and I bet they work just fine. There are a ton of similar VU-meter kits on the internet... I guess that I'll have to accept the modern approach on this... with op-amps =)

Regards

/John

 

[Rochey]

opamps and comparators.

thats about it.

 

[johnheath]

Yes, it seems like it.

So, can you recommend a yet simple but good circuit for lets say 10 LED's... preferably small in size too?

Regards

/John

 

[pucho812]

Been using these just lately...cant be arsed DIYing them anymore
Personally think they are the dogs bees.
Good price too
http://www.barmeter.com/en/viewproduct.asp?ID=197&XiajiID=1
Very fast with switchable modes.
Purchased thru their Ebay store,which took one week to deliver to the UK

wow cool. I wonder how easy it is to hook them up into existing diy stuff or otherwise?

 

[JohnRoberts]

There are numerous ways to skin that cat, depends on your comfort level with different technology. That last one I did (for a console) used a cheap micro and replaced an analog board full of op amps and comparators for less money with more features. Which was a win win.

For a one off DIY the software is probably not worth the effort.

JR

 

[weiss]

I know this is a but off topic, but I am currently planning to include a limiting indicator LED for my stereo 1176 by hairball. Does anyone know how to hook this up? I want it to be active when the SLAM mode is selected and audio is being limited..
Alternatively I thought i could use a LED bar VU meter and connect the LED on the top of the bar to the front panel. So each time the max level is reached, the light on the front panel will be active. Don't know if my plan works though.

Would be very thankful for help.

thanks
weiss

 

[ricardo]

The simplest is just to use LM3914/5/6 without any extra OPAs.  It's only if you want extra features eg peak hold that you need more.

Consult datasheet.

 

[PRR]

> VU-meter from LED's  without op-amps

1) Use comparators. For this they are better.

The LM3915 *is* a box of comparators.

Interestingly, nearly all commercial gear uses several LM339 (quad comp) instead of the '3915. Cheaper? More sources?

2) WHY? You need power for the LEDs.

You "could" drive LEDs from say a speaker-line, but they would fade-up, not switch-on.

RCA used a row of tubes and neon-lamps.

 

[johnheath]

Ok thanks guys.

OP-amps it is then. LM3916 seems to be the option?

https://www1.elfa.se/data1/wwwroot/assets/datasheets/ldLM3916_e.pdf

Since I am a complete noob when comes down to OP-amps I guess that I'll have a few following questions concerning hook-up… and maybe some other as well =)

Thanks

/John

 

[johnheath]

Ok - here's a thought from me

Attached is a scheme of a "typical application" of the LM3916 and ten LED's... from -20dB to +3dB ( like a analogue VU-meter). What I need is a bit of advice on if it is possible to just hook it up to a preamp and if so where... is it on the tip and 0V?

Is it the "signal source" that is the connection?

I also attach a scheme of a preamp that I have built that I like and where on that circuit should I connect the LM3916 LED VU-meter?

Please chew and spit if I am way of here.

Regards

/John

 

[johnheath]

And the pre schematic