U.RAT Demo Board

The u.RAT with stepper motors bolted in and coupled to the variable capacitor and roller inductor The two drivers and Raspberry Pi Zero W will be placed in between the capacitor and inductor. I have an Astron switching supply and a 12v to 5 volt step down component to supply the stepper motors and the Raspberry Pi Zero W. The NEMA-23 steppers only draw…

U.RAT is Ready for Open Sourcing!

The u.RAT is now ready for Open Sourcing, but I need to talk to the fine people at Elecraft about this, since the project is driven by the KPOD and is “KPOD Centric”. I guess someone could replace the KPOD with their own rotary encoder and switch instead of the KPOD, but I very specifically wanted to drive the project from the KPOD. The…

Adding the u.RAT Adafruit Pi-OLED

The urat.c program with printf statements ready to be replaced by OLED print commands . .  My good friend Mike, KJ4Z found a C Library for the Adafruit Pi-OLED, something my Google searches just didn’t find. Thanks Mike! Here is the link, and I shared it with Adafruit and their Support Forum – since no one there had found this wonderful C Library: https://github.com/bitbank2/oled_96…

Adafruit Pi Zero OLED

The Adafruit Pi OLED fits on top of the Raspberry Pi Zero W and uses I2C pins, not GPIO pins, which is really excellent Just plug it in and go to the Adafruit web site and look up “Usage” and follow the steps to ensure it works In a few days I will have this cute little Adafruit Pi OLED, and will be able…

Let’s Spin a Roller Inductor

As expected, even though the variable capacitor was a massive Palstar model, a roller inductor has more friction, hence requires more torque. When I spun it as fast as I could it drew just under 1 amp. That’s very reasonable. One BIG issue is that with “direct drive”, the set screws would unloosen – this is because the shafts of the stepper are stainless…

Let’s Spin a Variable Capacitor

There is more than enough torque for the large Palstar variable capacitor. There was little extra power drawn, but not much. I’ll try the roller inductor later today.

U.RAT Key Learnings

Here are some key design notes and learnings: I had to use a Raspberry Pi due to the fact that the KPOD driver software is written in C and compiled on Linux. The KPOD is a proprietary device using the HIDRAW protocol, so its not exactly the same as a keyboard or mouse The WiringPi library turns the interfacing part between software and pin…

The U.RAT Kill Switch and LCD Display

Spinning a capacitor is no problem – you can spin it as much as you’d like in either direction. But the roller inductor would not last if a high torque stepper motor keeps banging on its stops. My first idea (following the KISS rule) would be to just add some leds – green for L – and turn it on when the rocker switch…

U.RAT – Next Steps

I’ve cleaned up the uRAT code and removed probably 2/3rds of what was in the Utility KUSB that Paul, N6HZ wrote, and so now its close to as lean and mean as possible. I am sure if I download a code editor that has C dependency checking I can get rid of more lines – but for now its clean enough – all unused…

The uRAT Has Landed!

YEAH BABY, YEAH! The uRAT now works very nicely – exactly as I had envisioned it working: The “secret sauce” included: Elecraft sharing a KPOD utility that is part of their development and QA suite (thanks Paul, N6HZ and Eric, WA6HHQ!) WiringPi – Gordon Henderson of Devon, UK, who created a C library that makes it as easy to work with RaspberryPi GPIO as…