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Built the Mobius Strip and had to troubleshoot it for a little while to find and replace the wrong part I had installed into the board.  It is working now, and I like the sound.  Much cleaner than another pedal I built around the PT2399. 

One simple change I made was using a DPDT on-on-on switch instead of just the on-on called for in the BOM.  The recommended DPDT on-on switch swaps the feedback loops between the two delays (accounting for the "Mobius Strip" name for the pedal), while using the middle position of the DPDT on-on-on switch routes both of the feedback loops into one of the delay channels and just leaves the delay with no feedback on the other.  Sort of hard to describe, but it seems different enough from the other two switch positions that I wanted to suggest it in case others want to try it.

thanks.  I tend to tread cautiously with part subs on the VFE boards aside from the pots and filter circuits.

Has anyone has used a KY5050 voltage regulator as a substitution for the LP2950 voltage regulator on the VFE switching board?  I had ordered some LP2950s from Tayda Electronics and received the KY5050s instead (showing on the invoice as LP2050.  When I look up the data sheet for the KT5050 I see some references to the LP2950, but nothing saying they are direct substitutes. 

maybe even try 500K if you have one sitting around.

OK -- I misunderstood the role played by the opto-coupler in the circuit.  In that case, seems like the question would be whether Q1 is functioning properly (input and output).

You might also check that the wires coming into the board have not strays touching something they should not -- I've had that problem before.

have you checked to see if you are getting variable resistance from the opto-coupler?  the flashing LED suggests you are getting variable voltage going to it, but the part may be defective.

Thanks for adding those comments Peter!   And my continuing best wishes to you for the time and effort you spend training students at IDEA High School. 

: ^ )   

I guess that explains why you could describe the circuit as having "analog voicing" since the BBD is "bucketing" the sound bits even though the management of those bits is being handled digitally.  It is confusing since a number of articles will refer to the PT 2399 as a digital delay chip.

Looks like an interesting PT2399 delay.    I see that VFE describes this pedal as an "analog voiced" delay, but aren't all of the BBD memory chips digital delays? 

LOL!  pacman fever for sure...

Ordered a Mobius Strip last night.

The Klein Bottle is a great project for people that already have other guitar pedals (like most of us on this board), because you connect 3 pedals and can switch the order for the signal patch, and do something with customizing some feedback loops among the pedals too.   

Sounds like a fun project.  Looking forward to seeing how it develops.

Very interesting idea to have a stereo out with different voicing, with both channels feeding one output if nothing else was plugged in to the other (like the Boss Digital Delay pedals).  Would also be interesting to see what the differences are between the PT2399 and the MN3005, although it could turn out that the sweet spot for rhythmic repeats is less than the half-second or so you can get from the 2399.

I looked at the build doc and I am consistently impressed at the way VFE stacks the parts while getting consistent placements for the pots and switches.  Using the inline strip sockets on each side of the memory chips to free up a bit more space under the board was a good choice -- otherwise I guess those parts could have been mounted from underneath.

Of course that appreciation for the part density on the VFE boards only came after it took me two builds on the Choral Reef to get a working board (poor cap size choices, and trying to use too many sockets for the chips).   : ^ )