1. LoFI Future - OctoTron Expander

    PCB Design for the 8-Step Sequencer is almost done, Im calling this thing the OctoTron Expander. This sequencer is very primitive. As you will notice there are no step on/off switches and no transistor outputs to pull a proper gate from. It has simply one voltage output. The KORG Monotron likes to receive CV via gate for some reason, so sending this one voltage in to the monotron works just fine. You can also send this voltage into the cut off CV and modulate it, there is an on board switch to send the sequence to the pitch or cut off. The steps can be turned of by turning them all counter clockwise. This is possible thanks to a dead spot in the 1n914 diodes, when the pots are turned down, the 1n914 drops out all the voltage and basically breaks the connection, just like a switch.

    On board 9V and 3V regulators lets the sequencer and monotron run off of a 12V wall wart. Sync in is conditioned and wired to connect into the internal 555 clocks trigger input. It can accept basically anything you throw at it, from a TR626 clock to a line level audio signal.

    This board is designed to be mounted via its pot and 2 PCB standoffs from a custom cut panel that will also host the monotorn on 2 PCB standoffs and a supporting bracket.

    What this means for the builder, is an easy assembly that could be accomplished within half a day.

    This will work with all 3 monotron models. With the DUO its really nice since the voltage from the pots is pitched quantized in key.

     
  2. Custom Korg MicroPreset M500

    Mods:

    -Audio input routed to the filter

    -Red LED strip under key bed that strobes in time with the LFO

    -Trigger/Gate switch (military grade toggle switch, latching and momentary)

    (Source: lofifuture.com)

     
  3. KORG Octotron Auction Ending Today!


    (Source: lofifuture.com)

     
  4. Korg Octotron Demo/Explanation 

    (Source: lofifuture.com)

     
     
  5. KORG Octotron Demo/Test (Modified KORG Monotron with 8 step sequencer)

    Here are some sweet sounds of my latest synth creation with some keys (: (Delay from RV7000 reverb)

    Hoping to finish this project tomorrow, lets hope I don’t get lazy. 

    Oh and re-filming the S2800 bend tutorial over the next few days, lost half of the footage! just going to have to reverse engineer it for the video

     
     
  6. 8 Step controls fitted and soldered. Im just waiting for the rest of the switches to arrive before i install them. Also cutting out the acrylic panels now.

     
  7. Korg Monotron paired with an 8 step sequencer: The Octotron

    I decided to put the External HDD enclosure to the side for a while and use this wooden box instead. I’m making a top panel for the Monotrons controls and all the CV patching out of clear acrylic. The 8 step controls will be on the front of the box. The battery packs will be mounted on the underside of the box witch will be raised by four feet made out of circular cut offs. Since the only battery pack i had for AAA batteries was a 4 cell, i modified it to act as 2 dual batteries. I’m adding a switching circuit so you can select witch bay the monotron is powered off. great feature for live situations. The sequencer circuit is hidden in the box on its PCB risers. Expect a lot more progress tomorow, im working through this build quite quick.

     
  8. The korg monotron

    Here it is so far, i decided to use an on aluminium HDD enclosure. Looks pretty slick so far. It features a 4 step sequencer that sends gate and pitch CV to the monotron circuit. Thinking of adding some patch jacks in the unoccupied space at the bottom.

     
  9. VELLEMAN KIT - MK107

    Just ordered one of these Velleman kits. It’s a running LED module based off of a 4015 dual 4 stage shift register and a 555 timer. This circuit can be easilly modified to work as an 8 step analogue sequencer. It’s what I’ll be using to sequence CASIO SA-20. 

    There’s actually a really helpful here explaining how to do this project.