Katzenjammer Build Guide
Bill of Materials
R1 = 1k
R2 = 2.2m
R3 = 2.2m
R4 = 75k
R5 = 1m
R6 = 100k
R7 = 100k
R8 = 100k
R9 = 100k
R10 = 47k
R11 = 47k
R12 = 10k
C1 = 100n
C2 = 100n
C3 = 100n
C4 = 100n
C5 = 4.7u
C6 = 10n
C7 = 100u
C8 = 100u
C9 = 47u
D1 = 1n4001
"SPEED" = B100k
"VOL" = A100k
"WARP" = SPDT toggle ON-OFF (or ON-ON)
PIC = microcontroller included in the kit
ISD1820 = loop chip included in the kit
CD4066 = CD4066!
TL072 = TL072 or any op amp with the same pin-out
5v = 78L05 voltage regulator
Wiring Diagram
"SPST" is a momentary footswitch
"3PDT" is your latching bypass footswitch (notice it's "sideways" compared to typical depictions)
You can use a different type of footswitch wiring of course, just make sure "B" is grounded when the pedal is bypassed. This tells the microcontroller that the pedal is off and it will stop playing the loop.
PCB is designed to fit in a landscape 1590B, using Lumberg KLB3 audio jack sockets. Other types of socket might fit but I haven't tried any!
I also recommend this type of DC socket for an easier fit
The "R" connection on the PCB is for connecting two boards together for a Dual Katzenjammer. Just ignore it if you're making a normal single pedal, or message me if you want to make a dual one!
If you test the circuit before boxing it up, I've noticed the footswitch might seem to misfire sometimes. However, once boxed up the circuit will work perfectly. I think it's something to do with the speed you can press a loose footswitch at. If that happens, box it up and you'll be fine.
This pic is actually an earlier version, just missing the "B" and "R" connections
Schematic
Dual Katzenjammer
To solder two PCBs in parallel, we use the input buffers on both PCBs (connected at "I" on each PCB), then mix the outputs from each loop chip together on the first PCB by connecting the "R" point on both PCBs with a wire. We also need to connect the "B" points on both PCBs together at the footswitch.
So the PCBs connect in three different places: I, R and B, as well as at the DC socket.
Physically cut pin 2 off the dual op amp you're using for the second PCB. Otherwise the output mixers on both PCBs will be connected and strange things will happen (I think?)
You don't need to solder R6, R8, R9 and C4 on the second PCB, but it doesn't matter if you do.
Wiring Diagram
Lots of wiring, sorry...
Schematic
Hopefully that makes sense! If not shoot me a message - wraa.labs (at) gmail.com
You might find easier/ more efficient ways to connect them together. For example I'm generating 5v and 4.5v twice, once on each PCB, which isn't strictly necessary but it means less wiring at least!
