Electronics Merit Badge Workshop with Microprocessors

I had an opportunity to conduct a STEMulate Learning workshop for a group of Boy Scouts seeking their Electronics Merit Badge, which was a wonderful experience as always.

BSA Electronics Merit Badge

I had an assistant for the soldering/de-soldering station provided by the Texas A&M UniversityStudents Serving Scouting” student organization here on campus. The SSS folks are a tremendously dedicated group of young men and women who coordinate expertise and facilities for various scouting events through the year for Boy Scouts, Girl Scouts and Venture Scout crews.

As my assistant discovered, the SSS organization’s members are also personally involved as mentors and guides for our Scouts under the watchful eye of a designated Merit Badge Counsellor with specialized experience or understanding of the subject matter. Given a group of two or three dozen energetic, inquisitive young ladies or men that can be a difficult task but the TAMU SSS folks have never given complaint or expressed anything beyond the simple joy of working with their charges. I would certainly not have been able to teach lessons in reading diagrams or building electronic circuits if my assistant had not been staffing the soldering station while I rotated the boys through to give everyone a chance to complete their requirements.

One aspect of the BSA Merit Badge program is that while boys often work together, each must personally do all steps required to earn their Merit Badge. This is wonderful because it our courses are often the first time that some of these boys have performed even a simple task like measuring and cutting a piece of wood using a hand-saw for themselves. During the Electronics class, the boys spent a great deal of time in modifying their circuits and trying out various differences between digital and analog controls, parallel vs. series components, and other combinations of the equipment we had made available.

To experiment with a simple control circuit, I needed a simple and easily understood sample circuit the boys could use to do something simple like make an LED flash on and off. The scouts later adapted this circuit in several ways to create their own unique interpretation of a control circuit. Traditionally, I have always used a 555 Timer chip together with a set of components to build this type of circuit.

LED Flasher Circuit using 555 Timer

This design makes use of a 555 Timer, together with three resistors, two capacitors, one LED and a battery in order to cause the LED to flash on and off at a rate established by varying the two resistor’s values between pin1, pin2 and VCC. I wanted to reduce parts count to keep cost down so boys could take part without additional personal expense. None of the components were particularly expensive, but when you may have 50 participants it adds up.

I was looking through my electronics gear and realized I still had a batch of Atmel ATTiny85 microcontroller chips left over from last Christmas, when I was crafting multi-colored RGB LED pixels for a holiday display. These are Atmel single-chip microprocessors from the same family that is used in the Arduino boards I often use with teachers for robot control and e-textile designs. Single-chip microprocessors have the ability to store programs in on-board memory, so I modified a standard Blink sketch for the Arduino to create a simpler circuit than the 555 version I have been using for so many years.

LED Flasher Circuit using ATTiny85 Microprocessor

With only an 8-pin Atmel microprocessor, one LED, one resistor and a battery the boys were able to construct the same circuit as provided by the 555 timer. More than that because I had programmed several of the chips to do more than simply flash on and off. Scouts that had studied their Morse code quickly recognized S-O-S (…,—,…) and started trading chips with their fellows to find other hidden code messages programmed into the microprocessors.

Several scouts reprogrammed chips with my laptop so that their control circuits could do more with the additional pins of the Atmel chips, and the scouts spent an afternoon learning about electronics and digital controls. Several boys told me they plan to study Morse for the next time as well! A marvelous time for everyone and a great opportunity to share the fun of STEM topics with young learners.

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