Color Organ/VU Meter

[gnrfanatic1414]

I want to know how to create an LED VU meter out of this Color Organ Project, and use all Blue LEDs. I would like to use at least two "Bars" or levels using resistors, but I'm not sure how to do this. I have about 100 blue LEDs with resistors rated at 150Ω and will work with two LEDs in series using 9 VDC.

Video

**broken link removed**

 

[MrDEB]

Not sure what you mean by two bars or levels using resistors?
I think you want to run MORE LEDs instead of the 4 per channel?
One way would be to use a mosfet instead of the transistor 2n3904 then connect more LEDs in series with higher voltage .

 

[Reloadron]

The circuit you linked to is a basic color organ circuit and will not give you the VU meter effect. You want to look over and read the data sheet for the broken link removed LM3915 Dot/Bar Display Driver Cascading two of them as shown in the link would give you a VU meter with 3 db steps.

Ron

 

[MrDEB]

I myself was wondering the same thing but going by the video. If he wants a VU using the LM3914-16 then just up the available output as I suggested.

 

[Reloadron]

I myself was wondering the same thing but going by the video. If he wants a VU using the LM3914-16 then just up the available output as I suggested.

Yeah, I'm not quite sure what he is after either. But yes, your suggestion would work just fine.

Ron

 

[audioguru]

An LM3914 is a linear voltmeter, not a logarithmic VU meter which is an LM3915.

The OP wants to use the bandpass filters from the color organ circuit in an Audio Spectrum Analyser like this project (it has dim LEDs):

 

[MrDEB]

Egads not that schematic I toyed with couple years ago. The filters are ok but the output won't be very good (That's what I was told about the multiplexing circuit.)
One of these days I and Chris (Boy Scout now in college)will build that dang audio spectrum display and graphic equalizer project.
I spent many an hour with that schematic.

 

[gnrfanatic1414]

I want to keep the filters, but also have a vu on each of them to show the levels. Can't I just do this with resistors?

 

[audioguru]

The LM3915 is a bar-graph driver IC that drives 10 LEDs. It has a circuit inside that lights different LEDs with different input levels. It has regulated current outputs instead of resistors in series with the LEDs and has 10 comparators that detect the voltages. It has an adjustable voltage reference that sets up the levels.

 

[MrDEB]

If you download for free EXPRESS PCB then PM me I will send you the entire schematic ALL 6 pages for a 10 channel stereo equalizer/spectrum analyzer.
The project I worked on with LOTS of help from Audioguru and others.

 

[gnrfanatic1414]

does it work with a mac?

 

[audioguru]

does it work with a mac?

Does anybody use a MAC today? Why?

 

[gnrfanatic1414]

I do in fact. There is only one known virus for Mac's because of it's closed OS, and you get it through iChat, which hardly anybody uses. So don't hate.

 

[danrogers]

macs are only good for certain apple software id say.

guys, looking at the circuit, is there any alternatives to the TS921, as RS dont appear to stock them in th UK?

 

[audioguru]

Guys, looking at the circuit, is there any alternatives to the TS921, as RS dont appear to stock them in th UK?

I don't see a TS921 opamp listed. Motorola opamps are used but I would use a TL074 quad opamp and a TL071 single opamp that are made for audio.

 

[Reloadron]

The TS921 is a high output current rail to rail operational amplifier which can be found here. They use it for the virtual ground. You may find a possible substitution using a OP179 or OP279 from Analog Devices. The data sheet can be found here. That may work for this application.

You are giving up 20 mA which shouldn't matter for the application.

Ron

 

[audioguru]

The "virtual ground" opamp is not needed in the circuit. It feeds the extremely low current inputs of 4 opamps so two resistors and a capacitor to ground will do the same.

 

[MrDEB]

spectrum analizer portion

Here is a small portion of the schematic I have.
Download express PCB for MAC (lol) and I will email you the entire schematic.
THEN you can order some boards (I think it will fit on three separate boards (power supply, filters, display board
In theory it will work.
This project is not for a newbi.
Also have a schematic for a pocket unit that you plug an Ipod or ? into.