Shared Projects

Guitar integration board for Raspberry Pi 5 + HiFiBerry ADC2 DAC Pro. Includes two impedance matched inputs and two outputs featuring isolation transformers for ground loop problems.

Five Fish Tribute Opamp Test Jig (NOT FOR RESALE / NOT FOR COMMERCIAL PURPOSES)

NOT FOR RESALE! FOR NON COMMERCIAL DIY PURPOSES ONLY!

BOM and schematic are attached as pdf files below.

“FIVE FISH TRIBUTE” OPAMP TEST JIG

A friend of mine needed a test jig for discrete op amp kits he is building. My go-to recommendation for this was always the Five Fish Audio board — super straightforward, good options, etc. but since Five Fish has sadly passed, that project is no longer available.

Five Fish published schematics for many of their projects, including the opamp test jig, so I laid out a “new” one as a tribute. This project is completely and totally open source, as FF Audio had released the schematics presumably under that context, and is heavily marked as FOR NON COMMERCIAL DIY PURPOSES ONLY!

I’ve added a few changes to the FF board, including I/O jacks, a whole section for testing dual DIP-8 opamps one side at a time, various parallel footprints for different types of switches, etc. Likewise, I added multiple footprints for parallel resistors, since some of the gain setting resistors are oddball values and maybe you’d prefer to use “close enough” common values. Goal for this was to be able to build it out with parts you already have in your parts drawer.

Schematics, BOM, etc here: https://drive.google.com/drive/folders/1GjXNpyXrVJYEGH8Aos_KSex3xHcXm_Db?usp=sharing

[email protected]

Replacement joystick PCB for NES Advantage arcade-style controller

Tiny dev board for Atmel/Microchip ATF1502/ATF1504

See ATF150x_uPRG for programmer.

1M RAM Disk for Olivetti M-10

320K upgrade for 130XE (or 16-chip 65XE upgraded to 130XE). Resides under the PIA (6520) chip on the mainboard. One connection to extended DRAM pin-1, two-pin connection to SPST switch, to toggle between stock 128K with ANTIC bank support and 320K. (Memory MUX concept by Scott Peterson)

Assemble in the following order:

1. Install SMT parts

2. Install and solder 20-pin turned pin header strip on back of board for pins 1-20. You may want to use a socket or breadboard and both header strips while soldering to ensure alignment. Only solder pins 1-20.

3. Clip the pins short.

4. Install and solder 40-pin socket on top.

5. Install and solder second 20-pin header strip for pins 21-40 using same alignment method used previously.

6. Install and solder J2 and J3 horizontal headers.

NOTE: Do not use wide SMT ICs with NSR suffix. Use only narrow ICs such as SN74LS158DR and SN74LS157DR.

Installation:

1. Assemble board

2. Desolder eight xx64 DRAM chips (i.e., MT4164, M3764) on the right bank of RAM (extended).

3. Install and solder the eight 16-pin sockets where DRAM was removed

4. Using hookup wire, connect pin-1 of all eight DRAM sockets together.

5. Insert and solder new 41256 DRAM chips in sockets

6. Desolder the PIA chip, 6520 - take care not to damage the chip

7. Install and solder 40-pin socket in mainboard where PIA was removed

8. Install upgrade board in PIA socket

9. Install PIA into upgrade board

10. Connect single-pin Dupont wire to J2 and run to opposite side of board and solder to one of the Socket pins that you previously connected with the hookup wire.

11. Cut the 2-pin Dupont wire to about 4-5" and attach and solder the cut end to SPST switch

12. Plug 2-pin Dupont connector into J3

13. Mount SPST switch in suitable location in the 130XE case