Glass Blower GTI: Ultimate boost with VU meter!

[merlinb]

This is my latest version of my bootstrap booster, with a built-in LED VU meter! Totally clean, low noise, no colouration.

By using a rail-bootstrapping technique this pedal can deliver more output voltage than your ordinary 9V circuit can manage. Maximum output is about 11Vp-p! But unlike other pedals that use voltage multipliers, this one doesn't waste power continually, the voltage is only boosted when demanded. Total current consumption is less than 10mA. The intended application is to overdrive the front end of a valve amp (hence the name), but it's really just a high-headroom clean booster that could be used for anything.

It uses silent electronic switching, so in 'bypass' mode it actually acts as a unity gain buffer, and the VU meter continues to work. Again, this is ideal for a tube amp interface as it improves immunity to heater hum.

The lowest green LED lights when the output signal is about 60mVp-p. The top red LED lights at about 9.5Vp-p! I made a quick and dirty video clip to show this (the overdrive sound is coming from the amp not the pedal).

Schematic, PCB and more photos can be found here:
http://s81.photobucket.com/albums/j207/merlinblencowe/Glass%20Blower/

Video clip:
http://s81.photobucket.com/albums/j207/merlinblencowe/Glass%20Blower/?action=view&current=GlassBlowerGTI-1.mp4

[jplebre]

Nice!

Is there any way around it so the LED's stay on whilst the level goes higher?
Loved it though!

[frequencycentral]

The LEDs look just brilliant on the video. I'm gonna have to steal this idea.

[merlinb]

Is there any way around it so the LED's stay on whilst the level goes higher?

You mean bar graph? Yes, just cut the ground connection on pin-8 of U3 and connect that pin to +9V instead (i.e. the top end of R21).

[jplebre]

Ahhh! Brilliant!

Might steal this idea too!!!! 

[alfafalfa]

That was the shortest version of "Since I've been loving you"  I ever heard !!   

Looks good but I would like to hear a  longer clip if that's possible.

[merlinb]

Looks good but I would like to hear a  longer clip if that's possible.

All it does is boost. Not sure what you're expecting to hear except more volume...

[petemoore]

  If the centipede chip outputs supports charging of capacitence[s...
   Having the LED's drain the charge, timed LED fading would be possible.
 

[caress]

cool!

[culturejam]

Damn that's cool. Merlin, you are a smart dude. 

[Gordo]

Merlin, this is one of those gizmos that I really don't need, but it's so friggin cool I just have to build it.  Thanks for sharing this one, I suspect it will be on my board before the weekend.  If I'm gonna be a shoe-gazer I may as well have cool lights to look at.