Mobius Strip Dual Delay... delay... delay... delay...

[Chuck D. Bones]

This was one challenging build, but sounds great. Capable of generating some complex repeat patterns. Peter Rutter truly stuffed 10 lbs into a 5 lb sack. There are six resistors underneath each delay chip. The PT2399s have to be mounted on SIP rails to elevate them above the resistors. Even the Switching board is stuffed to the gills. The main filter cap is on the underside. I had to select the electrolytic caps very carefully because most of the ones I have are too tall. Had to lay down the charge pump caps. Now that I know everything is working, it gets disassembled for paint & labeling.





I had to do a little troubleshooting along the way. First, I had the 1N5817 diode in backwards. Then I had delayed signal, but no clean. There's only one part in the clean path that is not also in the delay path, it's the 15K in the center of the two pix below. Can you spot the bad solder joint?

Before


After


A little solder touch-up and it was good to go.

I built this one pretty much by the book. I subbed a 78L05 for the LP2950 +5V reg on the Switching board, a 0.82mH choke for the 1mH choke and a 10K trimpot for the 20K LED brightness trimpot because that's what I had. I increased one capacitor in the clean path to better filter out high freq noise.

 

[jjjimi84]

Looks fantastic! I love mine, what are you thinking for the graphics?

 

[Chuck D. Bones]

An acrylic pour. Something spacy to go with the sounds this thing makes.

 

[Barry]

Man that is a lotta stuff, can't wait to see paint job, swirl maybe?

 

[Chuck D. Bones]

Uh huh.

 

[HamishR]

I hope it sounds great and you use it every day! I've been looking over every board with a magnifying glass before it goes in the box these days - have caught a few possible bridges this way. Saves a huge amount of time in the long run. And since I got a finer point for the iron I have had fewer cold joints on PCBs.

 

[Chuck D. Bones]

I am digging it! It makes all kinds of interesting delay patterns. Only scratched the surface so far.
There is some of the infamous PT2399 noise/distortion, so I'm going to try swapping chips and also try the green LED trick that BurntFingers mentioned in the Troubleshooting forum.