Another Volume Pedal Retrofit Question

Started by JRM, March 26, 2013, 08:40:50 AM

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JRM

#20
Hi dear friends,

As usual, my diy projects are a loooong term battle :icon_evil: Work, family, source the parts... Now I'm taking this a second break... I've bought an Artec APW-3 not working to use the pot and rocker mechanism and go for this project with Johnathan's schematic but: it doesn't have one, it works with a "mag pot". It's a strange solution. They use a 78L05 to deliver steady 5V to an A1301 Hall effect sensor that delivers 2,35 to 4,7V to a voltage divider and then to an LED/LDR group. Rocking the pedal will change the A1301 output from 2,35V (heel) to 4,70V (toe). The APW3 has a range pot that interacts with the LED and the LDR making things a little harder to understand (smd and double face pcb helps to the pain  >:()
The good thing about taking long to finish my projects is that they get more focused on the goals! Why to insist in a variable gain to overdrive the amp when I already have several boosters and distortions on my board? I'll stay with a unity gain active volume pedal and use Johnathan's schem.
As the A1301 puts out between 2,35 and 4,7 I'll have to build a voltage divider in order to have between 1,4 and 2,8V at the controling input. Therefore a max of 0,7mA for a 2k resistance in series. Could this properly replace A1 and following circuit on Johnathan scheme?

guitarkill

I built this Anderton "VPR" project and found it was way too noisy for me. That is when I discovered the DOD FX-17 which is super quiet and has been on all iterations of my pedal board ever since.
just another dude killed by his guitar

PRR

> steady 5V to an A1301 Hall effect sensor that delivers 2,35 to 4,7V to a voltage divider and then to an LED/LDR group .... project with Johnathan's schematic

Can this get more complicated??

The LDR _is_ an audio volume control, or part of one.

Measure the LDR resistance, each end and in the center.

Figure out what range of gain you *really* need.

Post that and some sharp soul may see how to use a single opamp and a couple ressitors against the LDR to get your gain-range.
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