Right. I've found on the net an electronics kit which allows you to connect a line level or speaker sound output, and it will turn on a sequence of LEDs depending on the level of the sound (in mono). However, I've got a feeling that as its a kit it shouldnt be TOO hard to work out how to make myself, and probably cheaper (and I could customise it more easily). Heres a link to said kit : http://www.designnotes.com/velkitprice.htm K4304 10 LED MONO VU METER The object being that I'm going to wire this up to a set of LEDs which will be mounted into my case, giving me a "sound meter" sort of thing. Also, what would be the best way to get this wired to the sound card in a fairly permenant way?
http://www.gideontech.com/content/articles/210/1 And also search other modding sites, this mod has been made many times.
You can buy a stereo kit for £12, which includes 2 expensive ics, 20 leds and the pcb. Better circuit than above link, too. Get the schematic from the kit documentation download.
Thanks ! Hmm, thats interesting. Slight disheartening that its been done before a lot, but I'm not sure its going to be exactly the same as my application of it. I'm basically going to use them to "side light" bits of clear acrylic, which will be part of the front of the case. I'll probably want to make a switch to turn it off as well
why doesn't more people use the BA6822? it had 24 LED's.. (2x12) and peak hold... it also have adjustable rise and fall times... The LED driver is multiplexed aswell, so it uses only about 30mA... I made one using that IC... using blue and red LED's... looks great the chematics is already in the datasheet
Hmz matbe an original idea to modify the circuit above. Replace the leds with octocouplers and hook up ccfls to them
(a) nobody in the UK sells it, (b) surface-mount or shrink-dip packages only, (c) Sanyo's LB1412 is also 12-seg but a nice big DIL package
ah... sorry... i have the shrink DIP package... but nothing wrong with them? No problem soldering those... it's only a tiny difference from the normal DIL packages...
I used the 20 LED stereo VU meter kit from Maplin (10 led per channel) that was easy to fit together.
But now discontinued along with the mono version... Order Code: VF91Y Title: K4305 2x10LED VU Kit Status: Discontinued Order Code: VF90X Title: K4304 10 LED VU Kit Status: Discontinued
Exactly. Thus why I asked this quetsion I'll have a look at the schematics, see what would be easiest for me and what I can actually get hold of. Another question. How could I wire this up to my soundcard to give me the level without affecting the sound quality at all?
Do you have both line and speaker outputs? Taking a signal from the speaker jack shouldn't affect the sound from the line jack to your amp or active speaker system. If you only have the one output point, try with just a Y connection, screened cables to the vumeter. Any quality problems, you'll need to add a unity-gain op-amp buffer, very cheap & simple.
Buh... a wha? lol, sorry, I've got no idea what one of thems is! Ok, well, it looks like a Y-splitter it is then. OR I could get a stereo jack socket and some setereo cable (good quality of course ), and have an "audio out" socket on the case, so I can plug "the case" into the sound card, and still have a line out socket available. Now, this unity-gain op-amp buffer you speak of. Very cheap & simple perhaps... but what on EARTH is it?
http://ourworld.compuserve.com/homepages/Bill_Bowden/opamp.htm#opamp.gif Bottom-right schem in the first section.
The "voltage-follower" whypick1 linked. The output voltage is the same as the input (an amplifier with a voltage gain=1 but lots of current gain) but the input resistance of the opamp is several megohm so there's no extra load on the soundcard to affect quality. Check out the LM358N datasheet and AN-116 application note on the same page, it will run off a single 5V (or 12V) supply and is a dual opamp, so all you need for stereo.
The Fig 1 circuit in the LM3915 datasheet (on p9) using a PNP transistor will also do the job and looks easier to build for a single-rail supply.
