Airsoft / Paintball Chrono Project

Today I built a prototype Chronograph for Airsoft and Paintball (and Nerf!) using an Arduino and IR LED emitter/detector pairs, I am not sure it it will be fast enough for measuring airsoft pellets though. The initial code was pretty bad, it could only measure a maximum of about 5 fps! (Too much serial debugging going on)

Here is a picture of it, I will post more once I do more testing and debugging.

Chrono Prototype

The default ADC sampling rate is around 120us per sample which is not good for this project.
Thanks to some other blogs about high speed ADC on Arduino (that I have referenced in the source code) the system is now sampling at 15 micro seconds and using interrupts for better performance. I think 15us is good enough, but in case it is not I have ordered some IR detectors from amazon (Uxcell a14060700ux0143 SM0038 3 Pin Ground Vs Vout Infrared IR Receiver Module 250mV) that will allow me to use the digital inputs at 16MHz.

I am writing up a page to describe this project here.

Assembled Tank Tread and Motor mounts

Here is the assembled tread and motor mount. Using a 12V 2A power supply I tested each unit and found that they work nicely. The motors are 30 rpm, so 1 rotation of the wheel every 2 seconds resulting in a nice slow robot that should be easy for me to control with the Raspberry Pi.

The final assemlby is below.

Right side up.

Next I will be building mounts for the DC motor controllers and the raspberry Pi.

Raspberry-PI : Robot Tank Treads Progress

I have created a wheel design for driving the tank tracks for my mini Raspberry PI robot. The STL file is available here on

Also found a couple worm gear motors that will run at 30rpm at 12V (Unloaded) on . They have a 6mm D-shaft that is a little short, but should be ok.

Next step is to build a 3D design for mounting the motors and holding the wheels in position within the track.

Will try to post some pictures soon.

3D Printer Wanhao Duplicator i3 Plus!

A friend of mine is really into 3D printing, it looked like so much fun that I bought a ‘Wanhao Duplicator i3 Plus’ for $649 from the same place he got his, It has been a great experience so far. I have been printing almost non-stop for the last month! This printer is very well built and I can definitely recommend it to anyone wanting to get started.

I have been using for all my designs, here are links to a few of the models I have built. I am slowly building up a tank type robot for my Raspberry Pi. Fun stuff!

Nerf to Picatinny Rail Converter
Modified Picatinny Riser For Airsoft
8cm by 2cm Tank Treads for my Raspberry Pi Robot Project
Tank Tread Wheel for the Tank Treads

Here are my almost finished tank treads…

wxWidgets 3

I have not posted much on my website due to working on several big commercial (windoz) projects using wxWidgets 3 / OpenGL / SQLite / MariaDB. I used to be a big fan of Qt, however the licensing was way to expensive for me to use it for any project that I decided to take commercial, so I gave it up and dove into wxWidgets. I am happy to say that I have found it to be most useful as a general purpose GUI building tool, and superior in performance and simplicity compared to Qt. I am completely loving wxWidgets and I plan on posting a pile of wxWidgets instructions and examples in the future to help support the community of wx users.

Single Sheet Elevon based RC Aircraft

I recently built a sci-fi themed elevon prop-in-slot single sheet Airplane. My goal was to use only one sheet for an airplane that could fly with some of my smaller quadcopter motors, it weighs under 190grams (without battery). It uses a 5050-3 bladed propeller.
It flies great with either a 3cell 850mah or a 3cell 450mah battery even though the 850 is almost twice the mass of the 450. With the 450 it is so light that if you cut the throttle and pull the elevons back 50% the aircraft floats to the ground as light as a ball of tissue. Despite it’s aggressive appearance it is extremely forgiving to fly, and is suitable as a trainer.

190G RC Airplane
190G RC Airplane

A simple paint job using acrylic paint and foam brushes significantly strengthens the foam.
A simple paint job using acrylic paint and foam brushes significantly strengthens the foam.

RC Sim has new keyboard controls

I was playing without a gampad trying to fly my RC simulator and noticed how horrible it was, so I rewrote the keyboard controls.
The new controls do not require a numberpad, and are as follows:
[x] [w] for 100% elevator up and down.
[a] [d] for 100% aileron left and right.
[q] [e] for 20% throttle increments.
This is much easier to operate than the old method. So for people who want to try it out without a gamepad this is your best option.
Try it out here.

Review of EteckCity ‘Measure Up’ Digital Multimeter

This is the second product that EtekCity sent me for free for my honest review as part of their EtekCitizen program.
I requested this multimeter from them because I am constantly looking for my voltmeter, and needed an extra one to leave with my RC gear. This one retails for $16.98 on

Package for EtekCity Digital Multimeter

I have used this quite a bit in the last 2 days. I have too many large batteries around (for my Dalek, and a wooden go kart I built ), so I decided to give them all a check as well as test some continuity on some of the circuits I have built for my Dalek. I also did some resistive measurements on some bits of RC stuff as well. So far I am happy with this multimeter, it seems to work as expected. Is has a fast settle time (unlike my old tester) and the backlight makes reading the display very easy.
EtekCity Digital Multimeter
EtekCity Digital Multimeter

EtekCity Multimeter backlight

It feels very solid, and runs on a 9V battery. The only problem I have with it is that there is no battery cover, instead you need to take the unit apart (2 screws) to change the battery. Also it does not auto power down, so try not to forget to turn it off.
EtekCity Digital Multimeter taken apart
Disassembled for battery replacement check

Conclusion: I am pretty happy with it, it will have a permanent spot on my RC workbench.