Fusing Skills: Writing, Math, and Science

UnknownSince we’ve found bravewriter.com things have been starting to turn around in the writing department. We’ve learned to relax and let things develop a little more naturally (especially on those Friday Free Writes). However, today we did it on a Thursday!

I decided that it would be good to use Primo’s new-found love of electronics as a topic for this week’s writing. (Just explain to me how you did it Dr. Frankenstein).


The Project

Primo (now 11 and 11/12th) spent a large part of last weekend trying to solve the problem of more accurately measuring the pendulum swing for our follow-on to The Pendulum experiment.

He knew he wanted some kind of photo-sensor and the ability to detect the swing with the Arduino, but this time I told him he needed to design the circuit himself; whatever he comes up with will be fine. Begrudgingly, he set about to put the parts together, and by trial and error, and some algebra, he found a circuit that he liked. My only involvement was to answer the question as to why the voltage input to the relay was lower than he needed; this is what lead to the algebra to solve for the desired resistance in the circuit.

The next step was to have him tell me what the circuit does, how he did it, and then have him write it down. The following is the result exactly as he wrote it, including the pictures, using LibreOffice and Fritzing. I’ve left the grammar and spelling exactly as he had it; although LibreOffice fixed the spelling for him, there is time enough to work out the other details.

IR optical sensor circuitversion 1.0

This circuit will change states when there is IR (infrared) light applied to the phototransistor. It’s purpose is to help measure time between object(s) passing between the IR light source (most likely will be a IR-LED on final circuit), and the IR sensor.

Coming to the final product took some trial-and-error testing. I threw together a quick transistor circuit to find out that the phototransistor was working and just needed more amplification. So I built the same circuit but with a regular transistor instead of a phototransistor and put the freed-up phototransistor on the normal one’s base and, presto! More amplification! So I took the regular transistor’s emitter and collector in place of the photoresistor, shined the light on the phototransistor and (drumroll, please.)IT WORKED!

Now whenever it’s IR-dark; one LED is on, and whenever it’s IR-light; the other’s on! Plus! It’s extremely sensitive!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 IR optical circuit_html_m5895de7

IR optical circuit_html_cc283d2


The following video show a more complete circuit (added later) as we prepare to re-run the pendulum experiment.

What did we learn?

I think the biggest thing learned from this exercise was that we don’t have to get it perfect the first time; it being the science, the engineering, the math, and yes, even the writing. The point is to keep trying.

Most importantly, Primo learned that he can write.

Tell us your thoughts and how you encourage your children to write.


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