In this video I build a DC Load that’s controlled by a raspberry pi. I’ve built dc loads before, but this time I decided to up the goal to supporting 100w (it actually handled 200w) using three mosfets instead of one. I drive it with a DAC and read back the actual state using an ADC. The CPU board is a raspberry pi, and I have a VFD, encoder, and some buttons for control. It also has a web UI.
This project is about 24-bit stereo DAC, which we build for Raspberry Pi boards. This R-2R ladder DAC is developing around Intel / Altera EPM240T100C5N CPLD. We developed this module after review the PT8211 DAC, which we tested a few months ago. Compare with PT8211 DAC, this module is capable to provide high-quality audio output with Raspbian OS.
This project as described in www.surfncircuits.com came about because I needed a retro looking linear meter for my espresso maker water tank. I’m always running out of water in my espresso maker, and a cool display letting me know how much water is left and to let me know when to fill it up is definitely needed. In this project, I’ll create a HAT for the Raspberry Pi that can drive two IN-9 or IN-13 linear Nixie tubes. While I’m using this HAT as a single water meter display, this same linear display would be great for showing temperature, bar graphs, audio VU meters, even surf heights by days of the week. The Nixie Tube Power Supply, designed in an earlier blog will work perfectly to drive up to four of the IN-13 Nixie tubes or one IN-9 Nixie tube.
The Raspberry Pi’s 40-pin GPIO connector often gets overlooked. Typical Pi projects use the hardware as a very small desktop PC (RetroPie, Pi-hole, media center, print server, etc), and don’t make any use of general-purpose IO pins. That’s too bad, because with a little bit of work, the Raspberry Pi can make a powerful physical computing device for many applications.
Dr. Scott M. Baker wrote an article detailing how he turned a Raspberry Pi into a virtual storage device for ISA bus computers:
I’m tired of carrying compact flash cards and/or floppies back and forth to my XT computer. I like to do development at my desk using my modern windows PC. While I can certainly use a KVM switch to interact with the retro computer from my Windows desktop, it would be a lot more convenient if I could also have a shared filesystem. There are several alternatives, from serial port solutions, to network adapters. However, I wanted something that would emulate a simple disk device, like a floppy drive, something I could even boot off of, so I implemented a virtual floppy served from a Raspberry pi.
Dr. Scott M. Baker wrote an article detailing how he converted a Seeburg 3WA wallbox into a media player for his homebuilt audio player:
A bit of background. These Wallboxes were used as remotes in diners and other locations back in the 1950s. You put your nickel, dime, or quarter into the Wallbox, which racks up some credits. Then you select the song you want and the Wallbox sends a signal to the Jukebox, which adds your selection to the queue. Soon thereafter your music is playing through the diner. I’m too young to have experienced these in person when they were state of the art, but I do have an appreciation for antique and retro projects.
A new fad is to convert these wallboxes into remotes for your home audio system, be it Sonos or something else. I have my own homebuilt audio system, basically an augmented Pandora player, so my goal was to use the wallbox to control that.