For my project, I want to have two lines of LEDs display the volume of the left/right speakers. I got as far as figuring out the LM3914, and figured I would use one for each side, but what do I need to do to get the volume to the LM3914, without doing anything to the quality of the sound. If It matters, This will be for front headphone jack, and I plan on having the volume controll be on the faceplate.
You'd be better with the log-scaled LM3915, get the datasheet & see fig.1 in the Application Hints for a high-impedance input & rectifier circuit.
this kit is realy nice, if you want to build it yourself i have a circut somewhere... ill try to dig it up when i get home
So, I looked up the lm3915 and came across this So will I have to just make two of those, one for each side. The output will be a pair of headphones 95% of the time, will that cause any problems? or will I need a little amp or something for the lm3915
Are you planing to implement a switch for headphone <-> Speaker? I'm looking for one, and one that is'nt using a mechanical switch but some sort of flip-flop. Sry. for using you're thread but since it fit's the subject
Work out what's happening here. The two resistors R1=390, R2=2k7, on pin 7 turn the LM3915 into a 10V FSD meter. The ingoing R1=18k, R2=10k, divide the speaker voltage by around 3 for the 8R speaker case. So 30V to the speaker lights the full bargraph. That's around 80W RMS from the amplifier. Fair enough for a power amp. But you're going to have to change some component values to cope with the soundcard output, or that from a small headphone amp.
yeah, thats my concearn "The output will be a pair of headphones 95% of the time, will that cause any problems? or will I need a little amp or something" got any Ideas?
