Aquaboy Calibration and a few other questions

[bsoncini]

Hello, 

So I just built the aquaboy pedal.  Pretty easy build and the calibration was actually pretty easy.  Sounds great.  My question is it says leave the cancel trimmer in the center position unless you are calibrating with an oscilloscope.  I have an old techtronix that someone gifted me and I jump at any occasion to use it.   But I am far from an expert with analog delays.  To set the cancel trimmer what would I do/look for with the oscilloscope?

Another question.  I get runaway oscillation with the feedback at around 2/3. Anyway to get it closer to 100%?

Last question.  I've populated the mod board except the ldr and look forward to hook that up. Anyone know where to get a 9203 in Europe or a good replacement? Smallbear's site says that it is 5-20k light and 20m dark.  I can't find anything like that here.  I have some that are 100k light to 10m dark that I will try. I'll see how it works out.

Thanks in advance to anyone that can help.

[bsoncini]

I just found this googling dm2 calibration. The link at the bottom shows setup procedures.

http://www.hobby-hour.com/electronics/s/dm2-delay.php

Will try tomorrow. It's a bit late here and my girlfriend's gonna start complaining if I have a bunch of weird noises coming out of my amp.

[madbean]

Yup that's the right instruction to follow. I am currently without a scope so I just do mine manually and leave the cancel trim in the middle.

For the oscillation, you can adjust the feedback point by increasing the value of R30. Socket that and try 27k, 30k, 33k, etc.

For the photocells, 100k on resistance might be fine...it will limit the extreme settings of the depth control but that is okay (because you already have limited room to modulate a delay signal that maxes out at 300ms). If you find the modulation is too subtle with your available photocell, then omit R8 to increase the overall range.

[bsoncini]

Thanks Brian.

I calibrated this with my scope and I must say that in the end the trimmers were almost in the same spot as when I started. The cancel trimmer I put just slightly left of center. In the process, I found out unsurprisingly that the frequency calculator in my scope is more accurate than my multimeter.

This pedal has almost no noise and it's not boxed up using some random power supply I found at work.  I calibrated it following the instructions here. http://atomiumamps.tumblr.com/post/15659263080/boss-dm-2-adjustments

Just started playing around with the mod board. My ldr is a gl5549. The modulation definitely worked better cutting out r8. I need to keep playing around with LEDs. I have a yellow one in there now.

[madbean]

You know, I've never looked into it but I'm betting someone has done a study of luminosity vs. wavelength vs. light diffusion when it comes to LEDs and LDRs. I honestly don't know how critical wavelength is but I do tend to stick with red diffused in all mine. However, at least some of the 5c3 vactrols use a clear red 3mm led (I took one apart once).

[bsoncini]

Really I only popped a yellow one in because I had another build with a gl5549 that called for a yellow led. I figured they did some research before but who knows.

[bsoncini]

I played around with the feedback resistor tonight. Settled on 36k. Puts self oscillation right around fully clockwise. Thanks.

[sturgeo]

For the oscillation, you can adjust the feedback point by increasing the value of R30. Socket that and try 27k, 30k, 33k, etc.

I played around with the feedback resistor tonight. Settled on 36k. Puts self oscillation right around fully clockwise. Thanks.

Thanks for this, i tested mine and also got self oscillation earlier on than expected, i'll have a play with R30 

I have to say though, a wonderful sounding delay, my first experience with BBD chips and so far so good, well, better than good