Friday 5 May 2023

Aion Fx Aurora

 This one has been requested a few times by now...;-)

Schematic is avaiable HERE.


  1. It's a big one! Thank you Anders!!!!😊

    1. Yes it came out a bit bigger than I wanted to. At least you can fit it in a 125b box...

  2. I believe R7, the 1K resistor in the schematic, is missing. It should join between pin 1 of the 100K trimmer and the junction of R8 (1K) and R9 (200K). Probably a cut should be placed at H12 or H13 and then drop the resistor across it. I _think_ that'll fix it.

    1. I'm still working on this one. Attack 1 and Attack 2 are reversed otherwise it won't emulate the 150K-C, according to the build notes. The schematic has 10K for R18, but the build notes indicate that with the 15K and 300K across the Attack wiper: "R18 resistor (normally 10k) has been decreased to 100R". So I'm going to try 100R for the R18 resistor, between Attack 3 and the Q5 collector.

      I'm thinking I'll cut a trace at M7 and move the top lead of the 180pf down to M6, replace it with a 120pf (maybe even smaller), boost the 820pf to 1nf, boost the 360pf to 540pf, then wire an on-on-on switch as a 3-way to get closer to a Janglebox when the switch engages the 120pf. I'll label the switch positions: Lo, Hi, and 8-Mile Hi. This is going to be a must-have for Rickenbackers, I can just feel it.

    2. Some great observations there. I’ve been having trouble getting this one going myself so I’m following with interest.

    3. This one is killin' me. Here's my laundry list of issues, in order of egregiousness:

      1. The LM13700 requires +v be connected to pin 11. It's currently (heh) connected to pin 12, which is the output of OTA 2.
      2. Add a cut at V9, otherwise you'll have 9 volts connected to the collector of Q6, which is not ideal. This means the 47uF filtering cap has to move somewhere on the other side of the cut, like S17 and T17.
      3. The 10K (R24) connected to the Q6 emitter must be connected to ground, and the 10K (R23) connected to the Q6 collector must be connected to 9v. It's backwards right now. That means that 10K to the collector has to be super-short.
      4. This is a Ross/Dyna design with the "Q6 mod", so the 100nf cap at N6/P6 should be omitted, and you can remove the long N7-Y7 jumper as well.

      Already mentioned:
      4. Attack 1 and Attack 2 are reversed
      5. There is a missing 1K (R7) that needs to be added, so cut a trace at H12, and drop the resistor across it.

      I'll know more when I fix the LM13700's power situation.

    4. After making those 6 changes, this one finally fired-up. So easy! The changes can be done without starting with a new board. Just cut a few traces, add a resister, and shift things around a bit. I was lucky not to fry the LM13700.

      I don't have a 100K-C potentiometer on hand, and it really, really needs it, so that will have to wait. I ended up completely removing the 180pf treble capacitor so it now sounds like a slightly cleaner Janglebox (with a Release control!), which is exactly what I was hoping for. It's my new favorite toy.

      Just to be a pedantic weirdo, I _am_ using the type 1 on-on-on DPDT switch trick to turn it into a low, medium, high treble switch. You can find instructions on how to do that, but essentially add a wire between pin 1 and 5 on the switch, pin 2 is attached to "switch 2" on the board at E1, pin 3 isn't attached (high setting), pin 6 is attached to "switch 1" (medium setting), and pin 4 is connected to "switch 3" (low setting). Then the settings will be in order, low to high.