Hi all
I've been toying with the idea of installing some kind of volume meter into my pedal board and just wondered if this was even possible?
I use several drive and boost pedals each with slightly different volumes and I'd like some kind of visual aid to tell me what the levels are. It doesn't need to be massively accurate just basically tell me is pedal X louder than pedal Y.
Something like this would be perfect but probably with a few more LEDs
Is anyone aware of a project that might fit the bill?
Thanks as always.
I was just looking at a schematic for this...try google and pictures. Or the DIY hi fi boards.. I want to add a reverse gain or gain reduction meter to a compressor...
This would be remarkably easy using a microprocessor. Check out this project (http://www.instructables.com/id/Arduino-VU-meter-1/).
Bottom one looks pretty good...
http://www.4qdtec.com/LED/avu.html (http://www.4qdtec.com/LED/avu.html)
http://www.bowdenshobbycircuits.info/page11.htm#vumeter.gif (http://www.bowdenshobbycircuits.info/page11.htm#vumeter.gif)
http://www.free-electronic-circuits.com/circuits/audio-level-meter.html (http://www.free-electronic-circuits.com/circuits/audio-level-meter.html)
I have had the exact same idea myself, for the same reason. I would love to have something like that on my board.
Some LED volume meter ideas in an old thread at diy...
http://www.diystompboxes.com/smfforum/index.php?topic=102271.0
This would be really easy to do using an MCU. If you don't want to go the MCU way, there's the LM391x series that is in that last link that Dan provided. The LM3915 is the dB scale version. Here's a link to an Intstructables project that uses the IC, http://www.instructables.com/id/LM3915LM3916-VU-Meter/ (http://www.instructables.com/id/LM3915LM3916-VU-Meter/)
It would take a bit of scaling for the voltages to be right, but the project looks pretty easy overall.
Thank you for all the replies. Greatly appreciated.
I have zero experience with Arduino so a LM3915 circuit would probably be better for me. The circuit that blearyeyes linked to http://www.free-electronic-circuits.com/circuits/audio-level-meter.html looks pretty simple but I'm useless with schematics. Can someone with a good eye for these things tell me if it looks easy enough to build?
I'm surprised there isn't a PCB project for this kind of thing knocking around.
Thanks again guys!
Quote from: Guybrush on February 27, 2015, 09:24:24 AM
I'm surprised there isn't a PCB project for this kind of thing knocking around.
http://kuzyatech.com/lm3916-led-bargraph-vu-meter
https://www.tindie.com/products/kuzyatech/lm3916-led-bargraph-vu-meter-breakout-green/
Quote from: marmaliser on February 27, 2015, 10:51:40 AM
Quote from: Guybrush on February 27, 2015, 09:24:24 AM
I'm surprised there isn't a PCB project for this kind of thing knocking around.
http://kuzyatech.com/lm3916-led-bargraph-vu-meter
https://www.tindie.com/products/kuzyatech/lm3916-led-bargraph-vu-meter-breakout-green/
Perfect!
I've odered one.
Thank you!
No idea how to connect it up to my guitar signal but I'll cross that hurdle when I get to it.
LM3914's are about $2 ea. So are 10 segment displays. You can even stack multiple chips to get more resolution, like 20 or I think up to 100 LEDs. You don't have to use the 10 segment package. They are just 10 LED's conveniently packaged. I haven't used these yet, but I plan to. They're really simple to use and calibrate.
https://www.sparkfun.com/products/12694
http://www.ebay.com/itm/331414194726?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT&autorefresh=true (http://www.ebay.com/itm/331414194726?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT&autorefresh=true)
LM3915 kit from China 10 led meter... Cheap..
Ordered! Again though, no idea how to get a guitar signal running into it. Hopefully it'll be clearer once I get my hands on the kit.
Thanks!
Quote from: Guybrush on March 01, 2015, 09:14:33 AM
Ordered! Again though, no idea how to get a guitar signal running into it. Hopefully it'll be clearer once I get my hands on the kit.
Thanks!
Here are links to a hookup guide and video that may help.
https://learn.sparkfun.com/tutorials/dotbar-display-driver-hookup-guide
https://www.sparkfun.com/videos#all/TZxPjRrn_3U/8
Quote from: Guybrush on March 01, 2015, 09:14:33 AM
Ordered! Again though, no idea how to get a guitar signal running into it. Hopefully it'll be clearer once I get my hands on the kit.
Thanks!
I was thinking about that as well but it should be fun experiment. The sensitivity is adjustable but the range is pretty high. Might have to add a simple gain stage in front of the meter If the guitar signal is too low. Since it isn't in the audio path per se it might be easy..
Sometimes I wish I knew what I was doing.
http://pages.ebay.com/link/?nav=item.view&alt=web&id=231447448719 (http://pages.ebay.com/link/?nav=item.view&alt=web&id=231447448719)
A bunch of 5 LED kits for 8 bucks...
I ordered one, too.
Let me know how your build goes. I am wondering how to split the signal properly.
I received a couple of 10 LED meter kits from China. I'll post how they turn out...
Just built one of these up - https://www.tindie.com/products/kuzyatech/lm3916-led-bargraph-vu-meter-breakout-green/
I hooked it up to a 9vt power supply and to my guitar via a mono jack. As expected the output of the guitar is too low for the circuit to register properly. Even with the trim pot on the circuit board fully cranked I can only get the first LED to light.
Does anyone have any suggestions to increase the guitar output and so make the LED readout useable?
Thanks in advance.
Schematic and instructions can be find here:
http://kuzyatech.com/lm3916-led-bargraph-vu-meter
You can check valvewizard's vumeter that uses the same chip, and adjust the kit to it (schematic on page 9):
http://www.valvewizard.co.uk/glassblower.pdf
He seems to be using a level detector and a buffer but I only took a quick look. Here you have his notes about the vumeter:
Quote from: valvewizard link=http://www.valvewizard.co.uk/glassblower.html
My prototype GlassBlower turned out to be so useful as a general purpose preamp that I decided it would be nice to have some sort of metering, especially when driving other pedals since I don't really want to slam them with an excess of 9Vp-p.
The VU meter is done in the usual way by sending the audio to a peak level detector and then to an LM3916 audio-taper LED driver. Although this chip is designed to drive 10 LEDs, it is not easy to get the full scale out of it with only 9V available, so I used six LEDs. In any case, with six I managed to fit the whole thing into a standard small enclosure (Hammond 1590B equivalent). The lowest LED lights at about 60mVp-p, and the highest at 9.5Vp-p. Since I use electronic bypass the metering continues to work even in bypass mode- you don't get that with true bypass! This gives a really visual idea of how big raw guitar signals are (not very big!)
Current consumption = 15mA when active.
I just received my kit from china. Looks fairly simple to build. I don't yet know if I will need to look into some sort of amp for this, too. I'll post back up as soon as I build it.
Got mine built up, but it doesn't register anything from my pedal board. It will need some sort of amp, I assume. I have no idea how much signal it needs to hit the red.
I didn't use the supplied LEDs. I think the way I have it set up will be easier to mount in an enclosure. I have to drill a really straight line of holes, though.
(https://dl.dropboxusercontent.com/u/13215910/Web%20Images/20150323_184738a.jpg)
(https://dl.dropboxusercontent.com/u/13215910/Web%20Images/20150323_184754a.jpg)
If you have or have access to a drill press, clamp a fence or straight edge to the press table so you can slide the enclosure against it as you move from hole to hole and you'll achieve your nice straight line. Precise layout and center punching goes a long as well.
dave