Thursday, September 21, 2017

The Fundumoto motor shield

The Shield

If you are interested in Arduino robotics, animatronics or powered RC vehicles, you have probably run across the "Fundumoto" motor shield from Keyes. It's incredibly attractive for smaller builds of such things as it combines an L298 h-bridge motor driver, which many motor shields would have two of, with sensor headers for the rest of the unused pins, meaning ma of what you get from a typical sensor shield, at a cost in line with those shields. Since the facilities are perfectly adequate for those small builds, it allows you to do them with half the shields, lower cost, space, weight and power consumption. All good stuff!

Friday, September 15, 2017

Copies, clones & counterfeits


In this day and age of miracle electronics at unbelievable prices from overseas manufacturers, the terms copy, clone and counterfeit get used a lot. Some of these items are incredibly popular, meaning there's a lot of money to be made. Some are open source hardware designs, making the legal situation unusual.

People seem to use these terms for emotional loading that reflects their view of the ethics more than from any concern for consistency. I'd therefore like to propose a standard for usage of terms that cover the spectrum of possibilities.

I'll comment on the legal issues as well, but avoid the ethics except for the extreme case. And in each case, provide a little buying advice.

Sunday, August 6, 2017

Video on CPPM vs. S.BUS

I hooked up some receivers to an inexpensive USB oscilloscope to show you what they each look like, and explain why you'd want to use CPPM isntead of PWM, and S.BUS instead of CPPM.  Check out the video.

Friday, September 2, 2016

Measuring voltage on micro RC batteries

If you fly micro aircraft - or other things with small ~100mAh batteries and miniature connectors, you may have found checking the voltage to be a pain. Your standard battery tools can't deal with them, and the exposed contacts are just to small to get DMM probes into.

I found a solution. I ordered an SMD probe for my DMM for other reasons, but it arrived with a new micro heli. So it and the battery were sitting on my desk, and I had to try. Turns out it works really well for checking voltage on those batteries.

I recommend getting one of these probes just for those batteries. If it saves you one bad battery, it'd be worth the cost.

Sunday, July 3, 2016

Reviewing the DSO112A Coral mini oscilloscope

Why an oscilloscope

I hadn't really looked at oscilloscopes for decades, because I really didn't have much use for one. I only recently started doing electronics again, and tend to stick with things centered around microcontrollers and specialized digital modules. A circuit with even as many two analog components is pretty rare for me.
So I was surprised to see a reference to a $20 oscilloscope. Didn't think you could get one for even an order of magnitude more than that. So I investigated them, and found a slew of micro-controller based oscilloscopes ranging in price from that $20 - for a kit - to a little over $100. They typically have one channel, a small display, and a a very low bandwidth limit. But what do you know - I might even have a use for one!

Wednesday, March 23, 2016

diversionTx - a fork of deviation


Over the last year, I haven't blogged much because I've been working on deviation - the open source firmware I use on my rc controllers. Over the past few months, I've been thinking about forking it, and finally decided that I really need to do that.
Not that there's anything wrong with deviationTx as it is, it's just that the current project leader and I have radically different goals for what we want from the project. More than once, this has prevented changes I - and others - have wanted from making it into the deviationTx code. So at this time, I'm announcing a plan to create diversionTx as a fork of deviationTx to get feedback from the community.

Monday, December 28, 2015

FAA UAS registration requirement

If you aren't aware of it, the FAA recently created rules requiring pilots of unmanned aircraft systems (UAS) to register them.   I believe they are a violation of the law passed by congress, specifically the special rules for model aircraft, which I have already posted.

My comments to the FAA are:

Wednesday, October 7, 2015

RC blog entry on my programming blog

Just a short note to refer to the latest post on my programming blog, which is a close look at PWM input. It's an overview of the various methods of inputting a PWM value using an Arduino microcontroller, which is not something I've ever wanted to do outside the RC context. However, it includes code, so the post went to the blog, which has a repository for such.

Thursday, September 3, 2015

Roll Sensor for an RC Yacht

Roll telemetry data

I'd like to get telemetry from my RC Yachts beyond Rx voltage and RSSI info. For instance, the "optimal heel angle" seems to vary depending on who you listen to, so getting heel angle would be a nice start.

There are lots of cheap sensors that can report this, but none are targeted at yachts. So I'm going to build a simple one. Since I can't find rc radio gear that supports such telemetry, I'm going to hijack flight pack voltage on an aircraft system. Just read the roll angle from the gyro sensor (an MPU650 in a GY-521 board), convert that to a number between 0 and 255, then output that as a PWM value via a D->A circuit to get a voltage. The advantage of using an analog voltage sensor is that any radio system with flight pack telemetry can do this.

Thursday, June 11, 2015

The Joysway Orion


The Joysway Orion is another departure, being a sailboat. Or, as those in the hobby put it, an rc model yacht. If you're not familiar with such, you might want to read my introduction to it.

Thursday, April 2, 2015

HobbyZone Sport Cub S Review

The reason

Yup, this one is weird. The wings don't move! Not something I usually do. However, I like scale aircraft, and those aren't very popular for helicopters, at least not compared to aircraft. So scale copters are rare, and hobby grade ones tend to be expensive. I can find a number of airplanes I'd like to fly that cost less than a simple pod-and-boom helicopter of similar quality, never mind the cost of putting a scale fuselage on it!
So I bought this to learn to fly fixed wing, as that's what it was intended for. I also picked up a pair of floats for it, because - well, they were nearly free and look very cool, which is the point!

The aircraft

The Sport Cub S is an ultra-micro scale model of the Cub Crafters Sport Cub, which is a variant of the legendary Piper Cub. At that scale, it's missing most of the struts, and there's no cockpit detail, but it's about as close as similarly priced toy grade helicopters - and it's hobby grade. In particular, it has a steerable tail wheel, which is a nice touch in a an inexpensive model.