Kind of a resume

I’m looking into tutoring again and thought it might be useful to list a few links that illustrate what I’ve done. I may not have done the right stuff, but I have done stuff.

Arduino Park:

Grisbot 2-obstacle course:

Grisbot Follows the Light:

Triac/Reed Switch test:

Ultrasonic distance sensor as toggle switch:

Ultrasonic pinger game:

LED Figurine Illumination

Grisbot with Scratch Obstacle:

ATTiny45 light display:

Grisbot light follow test:

Also, here’s my video work on Modeling Molecules.

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Rocket Ship Freedom available for download

Rocket Ship Freedom

Rocket Ship Freedom is my YA novel about a teenager who gets an internship at a private rocket company and ends up going to the Moon, where he discovers a deadly mystery that threatens the survival of the human species.

Judging by the recent popular movies, the YA genre appears to be dominated by fantasy and dystopia. When science and technology do appear in a story, they often deal with really far out stuff like time travel and parallel worlds. Now, I like that stuff too, but I wondered how come there didn’t seem to be any YA novels that focused on hard technology and an upbeat vision of the future. So I tried to write a story that was scientifically accurate yet also fun and full of adventure.

View Rocket Ship Freedom at Amazon

(By the way, the cover illustration is my very amateur work in Sketchup and has several errors. Can you spot them?)

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Ultrasonic toggle switch

ultrasonic toggle

This is an idea for using an ultrasonic distance sensor (aka ‘pinger’) as a toggle switch. I’ll show it first and then explain:

As the hand approaches, the yellow light comes on to indicate that the switch is in aware mode.

When the hand is close enough, the green light toggles. That is, if it’s off, it goes on. If it’s on, it goes off. The yellow light, having done its duty, goes off.

The yellow light remains off while the hand is retracted to indicate that the aware mode doesn’t activate again until the hand is fully retracted. This is to prevent the ultrasonic equivalent of what is called ‘bounce’ in mechanical switches.

So what are the applications of such a switch? Suppose you have a runaway robot and you’re shouting at it but the background noise is high and so you take out your remote but there’s radio/IR interference too. You could chase after it and slam a mechanical switch on the back, but maybe that is getting too close for safety.

So here’s another solution: simply reach out toward the robot, and when you’re close enough (but still at a safe distance), the pinger detects your hand and deactivates the robot.

A more mundane application would be to turn fans and lights on and off more conveniently.

(In case you’re wondering, I had oatmeal for breakfast.)

Buy at Amazon:

Vivotech Hc-sr04 Arduino Ultrasonic Distance Measuring Sensor Module Good Compatible

Arduino Cookbook

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Debugging Touchless Technology


The comment that I added to the previous post was not the full solution to having a row of touchless buttons, but it set me on the way. A second pinger IS necessary to discriminate against anomalous readings.

In the following video, I turn off the yellow lights but retain a comparison between the distances from the finger to the lower (or ‘green’) pinger and the upper (or ‘yellow’) pinger.

Two comments:

1. There is still some confusion between readings for buttons. This might be corrected by setting the buttons farther apart and increasing the separation of the pingers.

2. You can see the light flicker as the finger hovers over the button. This is the equivalent of ‘bounce’ for a mechanical switch, and the solution is likely to be ‘debounce’ code.

Anyhow, it looks like the best way to use pingers for touchless technology is one pinger per button. That’s where I’m going next.

Available on Amazon:

Vivotech Hc-sr04 Arduino Ultrasonic Distance Measuring Sensor

Arduino Cookbook (2014 edition)

And still trying to sell my stories on Kindle:

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Touchless Technology with ultrasonic distance sensors


The concept behind this circuit design is that you can press buttons without touching them. As your finger lowers to the tabletop, the yellow light will come on, indicating that you are on the correct approach. Farther down, the green light comes on, which activates the button function.

Or so it’s supposed to work. What I find is that when my finger is on the lower level, the upper sensor will still detect its position, which is bad enough, but since it’s measuring at a diagonal, it will measure the distance as greater than it is.


Possible solutions would be to redesign the circuit so that there is a UDS pointing up from each button position. But that would require four sensors rather than two even for this circuit.

Hmm, I wonder how big the ‘spray pattern’ is for the sensor pings. If it’s fairly wide, then the position of the finger could be determined by triangulation.

Available on Amazon:

Vivotech Hc-sr04 Arduino Ultrasonic Distance Measuring Sensor

Arduino Cookbook (2014 edition)

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Touchless interface using pingers (set-up)

touchless 01

I’m about midway in building this demo of touchless technology. The idea is that the user will be able to operate buttons without touching them. Confused? It will all make sense when I get this thing running in the next day or so.

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Pingo: Ultrasonic Distance Sensor Game in Development

pinger hardware

This is the hardware for a game I’m developing that uses an ultrasonic distance sensor.

The microcontroller (Arduino, natch) randomly generates distances and then commences a ‘random walk’ from Point A to B. You, the player, hold your hand above the ultrasonic distance sensor (aka ‘pinger’) and the microcontroller compares the target distance with your distance. If you are within the ‘safe’ zone, you get a green LED light. If you are in the caution zones, yellow, and red is for when you’re way off.

In addition to lights, there is a piezo speaker which sounds increasingly high pitched tones when your distance doesn’t match the target.

Thus the object of the game is to move your hand so that it keeps in the green zone as much as possible. Points will be scored in the final version, and there will be different skill levels too. Following is a video of how it works so far. Please be patient, the gameplay is still in the development stage.

I’ve already gotten suggestions about generating oscillating waves and musical patterns in which distances correspond to musical notes. Please let me know if suggestions have occurred to you as well.

Buy at Amazon:

Vivotech Hc-sr04 Arduino Ultrasonic Distance Measuring Sensor Module Good Compatible

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