The Interlarding Fuzz

 
In·ter·lard
  tr.v. in·ter·lard·ed, in·ter·lard·ing, in·ter·lards
       To insert something foreign into...
 
 

Thanks to everyone at Aron's Stompbox Forum and Ampage for all your help and encouragement.  I've got you guys to thank for getting this far.

Have Fun and Good Larding!

The Schematic (the one I soldered together):

 
 

I didn't use R11 in my final version, but I changed R5 to 100k and R1 to 22k (as shown).  Capacitors C2, C3, and C4 are each switched with their own 6 pin DIP switches (S1, S2, and S3 respectively).

The capacitor values for C2 on my version are:

• 0.01uF
• 0.022uF
• 0.047uF
• 0.22uF
• 0.47uF

The values for C3 are:

• 0.015uF
• 0.026uF
• 0.47uF
• 1.0uF
• 4.7uF

The values for C4 are:

• 0.015uF
• 0.026uF
• 0.47uF
• 1.0uF
• 4.7uF
• 10uF

S4 and S5 are combined into a single DP6T rotary switch as shown:

(NOTE: where it says "Output" should be more appropriately labeled "positive side of C5")
 

 

Here's my PCB for all those who have been waiting for it (thanks to JD Sleep for the PCB templates!)
(NOTE: resize to scale before printing, and if you feel the need, flip it horizontally.)

This layout is a little tight for the capacitors, though there is room to space them out if you draw the traces a little differently.

 
 

Here's the wiring diagram.  Really just a badly labelled PCB layout:

 
 

Here's a sample of Bill Bergman's take on the layout (Thanks Bill!):

The expansion board for the switches and caps looks promising.  That will clean up a lot of the offboard wiring.

(NOTE: his entire layout including my notes are available here as a zipped Power Point File.  This gif file isn't as good as the ppt because of a lack of detail/resolution.  Bill told me about it being a raster-farian or something : )
interlard.zip

 
 
 

Now once you have this done,

you'll  need to start playing with all the knobs and switches to get some sounds out of it.
There are a lot of dead zones, and even more squealy settings.
What we want is a setting that is just on the edge of squealy.

The following is a set of instructions of simply tuning the interlarder to get a sound.
 

Do the following in a remote location or while everyone is out of the house.  If you live in an area where air-raid sirens are the norm, be sure to warn your neighbours and local authorities that you will be working on a new noise-maker.

• Plug in your Interlarder make sure you have the power connected.  But don't turn on your amp yet.
• Turn S1 and S2 off (open circuit) and S3 to open circuit if available (DIP switch wiring) or to the smallest capacitance (rotary switching).
• Switch the transistor selector switch (S4) to PNP transistor (Q4) and switch the output selector to tap the collector junction of Q1 and Q2.
• Turn all the knobs to one extreme or the other, I reccommend R1 on no resistance, and R8 on no resistance to ground from wiper, R2 shouldn't matter that much at this point, as long as it is at an extreme.
• Plug in your guitar, with the volume turnted down.
• Turn on your amp with the volume at 0, then turn it up slowly to a low, but audible volume.  You may hear a hum.
• Slowly turn down R1 it should click or pop once or twice and any hum should dissapear.
• Slowly turn up (or down) R8
• Once you hit a squeal back off slightly and play a chord
• If you still get no sound turn all pots to the other extreme and start again.
• If you still get no sound after playing with pots, then fiddle with the switches and pots

Here are some working voltages, your's will vary depending on the settings.
 

• Power Source = 9.18V at 1.5mA
• Positive Supply Rail (after R1) = 0.781V
• Q1-PNP: (E, B, C) = (0.779, 0.315V, 0.778V)    (perhaps the guitar signal provides the "turn-on" voltage?)
• Q2-NPN: (E, B, C) = (0.9mV, 0.473V, 0.778V)
• Q3-NPN: (E, B, C) = (46.6mV, 46.6mV,  0.734V)
• Q4-PNP: (E, B, C) = (0.734V, 66.6mV, 46.6mV)

These are just the voltages for the initial setting (maybe with a few knob twists to focus.  You should be able to run the interlarder for a few years on one battery, not only because it draws very little current (on some settings), but it also works with a 9Volt battery running at 4 Volts.
 

This completes the Interlarding Fuzz page thus far.  Check Mr. Bergman's layout for more Interlarding notes.
Maybe it would be a good idea if I posted other settings (cap combinations and pot positions), so if you find something good tell me and I'll post it.

Contact me if you have any questions, concerns, problems, ideas, or anything else that I can assist you with.
krustykorp@hotmail.com