Mad Bean's Holy Roller low output level

mybud

mybud

Well-known member
Came across this schematic recently and have breadboarded it for testing. I used an NSL-32 as recommended by a fellow builder and it seems to function ok, but with a very reduced gain. I observe that the LED indicator (parallel with the vactrol) stays lit all the time.

I also notice that @bean no longer offers the board and was wondering if anyone else has tried this and if so, what their results were. It's an old circuit judging by the copyright date so there may be some insoluble problem that I'm trying to solve here. Any advice gladly received.


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Solution
J
I think this was only ever offered as an etch/diy PCB.
Did you use an LED and a NSL-32?
Not sure what you mean by "led parallel to the vactrol". Or did you just insert a led parallel to see? D1 should be changing luminosity when playing...
Others reported good luck with a LDR with 1meg Rdark and red lwd. A NSL32 is only 500k Rdark.
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I think this was only ever offered as an etch/diy PCB.
Did you use an LED and a NSL-32?
Not sure what you mean by "led parallel to the vactrol". Or did you just insert a led parallel to see? D1 should be changing luminosity when playing...
Others reported good luck with a LDR with 1meg Rdark and red lwd. A NSL32 is only 500k Rdark.
 
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Solution
jwin615 said:
I think this was only ever offered as an etch/diy PCB.
Did you use an LED and a NSL-32?
Not sure what you mean by "led parallel to the vactrol". Or did you just insert a led parallel to see? D1 should be changing luminosity when playing...
Others reported good luck with a LDR with 1meg Rdark and red lwd. A NSL32 is only 500k Rdark.
Click to expand...
Thanks for the reply, @jwin615. I wired the indicator diode across the diode of the NSL-32. That it stays on all the time bears out what you're saying regarding Rdark.

Let me try this with a home-rolled vactrol setup. I have a couple of LDRs (5516, 10720) that may be closer to the mark than the 32.
 
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mybud said:
Thanks for the reply, @jwin615. I wired the indicator diode across the diode of the NSL-32. That it stays on all the time bears out what you're saying regarding Rdark.

Let me try this with a home-rolled vactrol setup. I have a couple of LDRs (5516, 10720) that may be closer to the mark than the 32.
Click to expand...
Ok, LED still stays on but much more gain. There seems to be an issue now with the level control which only allows signal at full CCW. I'll do a proper job of sealing the vactrol and recheck the wiring, probably some silly error on my part. Thanks again in any case.
 
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This Limiter keeps getting pushed down my build queue, but mybud's build report here has pushed it right back towards the top!

mybud

Thread 'Bean LA2A optical limiter'

I breadboarded this last September, according to my notes, but couldn't get it to work at the time. I built it from @bean's original 2016 schematic.

IMG_4422.jpeg

Futzed about with it yesterday and found it functional but squealing to beat the band. At least the level pot seemed to work but obviously unuseable as it stood. Last night I double-checked the components and found a 6k8 sneakily masquerading as a 68k MFR.

Corrected this and resumed double-checking this morning to find an off-by-one error which effectively disconnected one end of the vactrol (NSL-32 in this case) from...
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  • This ROCKS!


This would be the perfect circuit to add after an unruly envelope filter, such as taming the DOD FX25's resonant volume spikes, for example.

So I'm thinking combo build, with the option of toggling between either circuit to run them independently or together — with a two-knob envelope-filter or other circuit, a compact 4-knob pedal... 'twould be awesome!
 
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Feral Feline said:
This Limiter keeps getting pushed down my build queue, but mybud's build report here has pushed it right back towards the top!

mybud

Thread 'Bean LA2A optical limiter'

I breadboarded this last September, according to my notes, but couldn't get it to work at the time. I built it from @bean's original 2016 schematic.

IMG_4422.jpeg

Futzed about with it yesterday and found it functional but squealing to beat the band. At least the level pot seemed to work but obviously unuseable as it stood. Last night I double-checked the components and found a 6k8 sneakily masquerading as a 68k MFR.

Corrected this and resumed double-checking this morning to find an off-by-one error which effectively disconnected one end of the vactrol (NSL-32 in this case) from...
  • Like
  • Love
  • This ROCKS!


This would be the perfect circuit to add after an unruly envelope filter, such as taming the DOD FX25's resonant volume spikes, for example.

So I'm thinking combo build, with the option of toggling between either circuit to run them independently or together — with a two-knob envelope-filter or other circuit, a compact 4-knob pedal... 'twould be awesome!
Click to expand...
And so it would, Feral. I’d completely forgotten about this particular thread of woe from last September. Thanks for the reminder and to everyone who pitched in to advise. Pretty sure I did something stupid in this case (missed connections, what have you), so fixing the rebuild and getting it to work is a minor victory of sorts. I do think it will work well with a quack box exactly as you suggest. Will give it a spin and report back.
 
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