I am currently working on trying to build a LED spectrum analyzer. I hope it to be a 10x10 at the least and I don't want to use micro-controllers or PICs. I have seen the velleman 4300 design BUT the U2067 is not made anymore . Is there a way that I can multiplex the LM3916? Or should I just use 10 of them and build filters for each channel?

 

I would go for filters on each channel.

I would guess of a solution like this:
For each channel:
1. filter
2. rectify
3. might need to amlify dc value.
4. lead this into a lm3916.

Repeat 10 times.

Interresting problem to try finding another solution so we doesn't have to make up 10 nearly identical circuits.

 

Hmm... that's what i was afraid of... I was hoping maybe i could replace the U2067 with the lm3916. Any Ideas? It seems simple but I haven't the experience yet to know for sure. Also... Are there any circuit design programs and circuit simulators on shareware for a mac out there??

 

There is a old post titled "Peak meter for certain frecuencies".

 

If you multiplex a single LM3916 then the 30mA output becomes an average of only 3mA in each LED which is very dim.
If you use millions of transistors then the LEDs will be brighter and only one LM3916 can be used with a switcher from each bandpass filter.

Use 10 LM3916 ICs.

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Uncle $crooge

 

Hmmm... The Velleman circuit makes use of transistors at the obsolete IC. Maybe I could ultimatly use the lm3916.... does anyone know where i can get spec sheets for the U2067?? That would help out alot...

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Sometimes life can throw lemons and potatoes at you, I take them and make light

 

You probably want the LM3915 instead, as its 3db steps are closer to the original 2db steps of the U2067B. The LM3916 sports steps for a VU meter (-20, 10, 7, 5, 3, 1, 0, +1, 2, 3db).

Display brightness may be an issue, as AG states, because you're cycling through ten rows, hence 1/10 the brightness. But, the original Velleman kit does the same thing. EDIT: With the values they're using it looks like the LEDs are being driven with about 45-50mA, so it may be okay (4.5-5mA average current). You could drop the 270R resistor a bit to get more brightness, say to 120R/2W. That would give you 10mA average. Also, you'll likely have to dork with the input level at the LM3915 some to get it to work properly. Who knows what the original U2067B did.

In terms of a datasheet, all I could find was this, which basically shows that an LM39xx may get you there. Also, there's a German site that appears to have the datasheet, but it's a pay-per-use or subscription service: data sheet information for U2067B from www.ecadata.de).

Attached Thumbnails

 

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Go Trojans!

 

The "Peak meter for certain frecuencies"!!! Nice old memories. I never finished the construction, I ran out of money. 10 Lm3915 would be very complex and expensive! Maybe if you buy them directly with the factory they would be cheaper?

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Felipe

 

I bought an LM3915 for $1.00CAN at a local surplus electronic parts store (Sayal). They buy overstocked parts from equipment manufacturers who don't need them anymore.

My Sound Level Indicator project's prototype still works 24/7 and is almost 3 years old. It uses an LM3915 with an automatic gain control to give a range of 50dB. It shows a pin dropped on the floor in the next room and loud music in its room.

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Uncle $crooge

 

$2.65 ea at Jameco, or $1.94 ea for ten.

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Go Trojans!

 

I found out a bit more about the U2067B by scrounging around through some German web pages, which I drew it up in case it's useful. The thing is a Stereo Level Driver, with each half doing five LEDs and having some sort of precision rectifier.

If the supply voltage is high enough, LEDs can be arranged as drawn, and are sourced with 15mA constant current. As the supply voltage gets less and less, the lower LEDs must start to be wired in parallel. And finally at 7V each output gets its own LED to ground, with a pullup to +Vs, all except the first. The pullup values determine LED current. The chip shorts out each LED as the input voltage falls below the indicated threshold values.

"Aside from the built-in rectifier, the input op amp is used as any other, and the non-inverting input is grounded internally." If the input op amp is not used, the rectifier output pin can be used directly as the input.

Attached Thumbnails

 

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Go Trojans!

 

Sweet!! Thanks for all the help Ya'll I think I can get it together and figure out any information i need from what ya'll gave me! I think I'm goin to make a stereo version of this and have the two stacked one on the other where the lowest amplitudes are nearest each other. I'm goin to paste my schematics as soon as i can get it together and possibly a video of it working.

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Sometimes life can throw lemons and potatoes at you, I take them and make light

 

Does Anyone know of any free Circuit Building Programs?

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Sometimes life can throw lemons and potatoes at you, I take them and make light

 

Do you mean schematic capture/PCB software? Below link has a free version of which you seek

CadSoft Online: EAGLE Layout Editor

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Pay it forward.

 

Maybe Even some programs that allow for testing as well?

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Sometimes life can throw lemons and potatoes at you, I take them and make light