abfackeln a écrit :
Several of you have been asking about these, so here's the "first pass" at some add-on projects for analog delays. These have been tested on madbean's Aquaboy prototype and the Aqua Puss project boards, and should work for any similar circuit (DM-2, AD-80, etc). These were tested with the MN3005, but should also work on madbean's Aquaboy if you're using the V3205, since polarity switching is handled on the main board (but I have not tested with the 3205).
I'll also say that these are not so much my "own" work, but rather a compilation and tweaking of projects and ideas found within this forum. The project files are fairly rudimentary (I'm no madbean), but these should get you there.....
Double-Delay:
Increases stock delay time from 300ms to ~600ms. This one's essentially Dirk Hendrick's double delay schematic for the AD-9 in another thread. There's two versions in the file:
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Double-sided etch - this ones a tough etch because of the small size, but it works perfectly. Onboard bias and cancel trimmers.
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Single-sided etch with top-side jumpers - This ones a little easier, but loses the cancel trimmer (I have not yet tested this version).
The offset pads on IC1 are for the connection to the main board's bbd. I used left-over resistor clippings for the "pins" that attach to the pads, and these plug into the main board's bbd (I used a socket there) in a 1-to-1 configuration.
Worth noting - if you're planning on building madbeans Aquaboy into a 125B, you may want to forego sockets on the daughter board and solder the bbd's directly to the board, but still use a socket on the main board. Height quickly becomes an issue with sockets on both boards.
Modulation:
Adds on-board chorus/vibrato modulation. This one's based off Rick Holt's (frequencycentral) LFO for the Midfi Clari(Not) (which looks similar to the Magnus Modulus LFO). The trick here was the LED/LDR combo, which produced pleasing results. Without it I was only able to get mild chorusing. These are fairly easy to make with a high-brite white LED, and LDR (I bought mine from Radio Shack) and some heat shrink tubing. I had an assortment of LDRs, and picked one that was roughly the same size as the diameter of the LED. You can hot-glue them together, but I just held mine together with the heat shrink. Lower settings on the depth knob get you the chorusing, and higher settings take you into the "seasick" territory..... I used a TL072 for the IC, but I believe any "standard" opamp will suffice.
In the second picture below, you can see the LFO board mounted behind the 3PDT:
Expression pedal:
This is the poor-man's implementation of an expression pedal control, taken from R.G. Keen's article. It uses a stereo switched (NC) 1/4 jack, and a TRS cable. This will work for any of the pot controls. Don't connect the pot to the board - rather, connect the pot to the non-switching side of the jack, and the other side of the jack to the board. Then find an old wah/volume shell, and install another pot for the control. For my build, I chose to control the feedback/rate pot (50KB) - I made an antilog pot at 50K (from 100K) from modman's suggestion in another thread, and wired it to a stereo switch. With the pedal connected, it controls the function, and disengages the on-board pot. Disconnect the pedal, and the on-board pot is engaged again.
For the stereo switched jack, I used Mouser part #550-NMJ6HCS. Again, if you're planning on building a madbean board into a 125B, you may want to opt for the 1/8" version instead of the 1/4" to help save space. It'll also help keep you from mixing up the TRS cable with your other cables....
And here's everything into my main AP - double delay, modulation (the two smaller knobs at the bottom), and exp pedal input at the bottom.
