notes to self

Author: abram

  • SCHEMATIC: TL082 9V Active EQ…

    an experimental EQ circuit based of the TL082 datasheet. i modified it to use a 9V battery, but could probably still use some work in terms of efficiency… as most things. nothing is ever finished really. the mid portion has a pretty high quiescence. fine tuning, of course, can be done with the resistor values…

  • SPICE: ngSpice plot test…

    nothing too special here. i’ve been practicing my SPICE skills and attempting to work with a single-supply active EQ circuit based on the TL082. further research of this chip has pointed out that the TL072 is better for audio applications, but it seems that the differences are pretty minuscule. here’s the spice code with the…

  • Mellotronium revised…

    here’s an update on the new additions/approach to the Mellotronium. i’m attempting to redo the SD card routines once i get the functionality added. using the SD library just doesn’t work right when reading byte values at 8kHz. i’ve looked into the WaveHC library with the most success, but had to modify not to use…

  • mobile APRS setup…

    here’s a picture of my mobile APRS setup in the Jeep. it’s been a fun project from time to time. eventually, i plan on constructing a 2m vertical antenna to throw on the roof for better satellite reception while being mobile. i’m currently using a high-gain Comet mag-mount which is an excellent antenna. i was…

  • the Stirgiform PT2399 delay…

    two days worth of soldering and layout. it’s a combination of the Magnus Modulus and Rebote delay schematics. i couldn’t get the mixing circuit to really work from the Rebote schematic (an older version) without some serious distortion, so i just kind of reworked it on my own. here’s the schematic. i wouldn’t commit to…

  • Arduino: LFO Generator

    here’s a treat for anyone that’s into the audio side of arduino. it’s an 8-bit two-timer based LFO Generator using timer 0/2 on an ATMega328p. i’m only using timer0 for output in this code. i’ve started implementing the LFO code into my 8-bit melotronium where timer2 is dedicated for the audio output. in the larger…

  • Arduino: the 8-bit Mellotronium prototype

    i’ve been pretty Arduino obsessed over the past month. i got in my head this idea about building a midi-controlled digital sampler that uses SD cards for storage after thumbing through the Arduino Cookbook and have finally started to make some headway on the project. there were some major obstacle to overcome, unfortunately. the first…

  • Arduino: second verse, same as first… sort of

    well, not really. feeble attempt and making some sort of microprocessor controlled tempo clock, but a good exercise in the ATMEGA328s finicky behavior. don’t ask me what that squeal is. i think it comes from the way the input was wired up (mistaking the second sleeve as a synonym for ground) coupled with the PWM…

  • Arduino: Analog Aerials

    Essentially the oBITerator program with aerials instead of actual input signal. Of course, we’ve got to mix in the newly constructed PT2399 pedal. A little work needs to happen in the common-collector preamp in the delay pedal. I’ll be recalculating those values soon as well as switching out a couple of the ceramic caps. They…