Tone guard device by pcb guitar mania

[harrisxr650]

Hey people.

Just finished the tone guard device from pcbguitarmania. Can someone clarify the positioning of LED/LDR is ok before I heat shrink them? Also I've noticed that the led is not going full bright , is this normal?

Thanks

[GibsonGM]

Looks about right to me!  Why not set it up w/guitar, and turn off all the lights?  (get it into the dark...even a closed box or something).

Then you'll know what is really going on!    Sometimes the LEDs on these things don't light up "all the way" on purpose; I think you have to let your ears decide. 

[harrisxr650]

Looks about right to me!  Why not set it up w/guitar, and turn off all the lights?  (get it into the dark...even a closed box or something).

Then you'll know what is really going on!    Sometimes the LEDs on these things don't light up "all the way" on purpose; I think you have to let your ears decide. 

I have never build an optical pedal so i wasn't sure how to position the led and how bright it should be. my though, and from what i read around is to place the brightest spot of the led to the ldr.
the pedal sounds really cool but i think the attack and release knobs are very subtle, will test i again tomorrow as i couldn't play at a normal volume.

anyway. thanks for the help  

[antonis]

I think a "4 legs device" should be more efficient..

[harrisxr650]

I think a "4 legs device" should be more efficient..

i can give it a go, led shouldnt touch ldr or its like that for scetch purposes?

[antonis]

I think the distance between LED top and LDR should be that of not permiting heat shrink tube to "block" part of light emission area..
(a couple of mm should be fine..)

[ElectricDruid]

i can give it a go, led shouldnt touch ldr or its like that for scetch purposes?

There's no reason why they shouldn't touch. It's only plastic touching plastic. It won't get hot, and in terms of electrical isolation, only light passes between them, so it makes no odds. If it makes it easier, get them tight together. It should work better like that.

[ThePracticalPeasant]

I immediately wondered why not use an opto-coupler... I share my findings:

Apparently, the ones from the 60s (Vactrols) were made out of a neon and a photoresistor. These days, they're made out of Silicon junctions, but there are all sorts of opto-isolators available out there these days, that have all sorts of behaviours. I wonder what could be done with the modern equivalents.

I also found mention that [Vactrols] were previously used somehow to modulate a tremolo effects [and others], but I haven't yet found any information as to how that was done.

...Pardon the interruption, as you were!

[Ben N]

I don't know if there is any real benefit, but when I make these, especially in a device that uses more than one of them, I use two layers of shrink tube, the inner one of a light color and the outer one black, the idea being to improve isolation and maximize light transmission. But I always have them touching.

[marcelomd]

Never did it myself, but saw recommended a few times: sand the top of the led (not to the actual device, of course). It spreads light a bit more evenly and allows it to sit perfectly flush to the LDR.

[antonis]

I have to disagree, Marcelo..

"Flat head" or "Straw hat" LEDs aren't so good for focused light..
Especially, those made after top sanding, are worse 'cause light inwards reflection due to grainy surface..

[marcelomd]

I have to disagree, Marcelo..

"Flat head" or "Straw hat" LEDs aren't so good for focused light..
Especially, those made after top sanding, are worse 'cause light inwards reflection due to grainy surface..

Noted!