The Human Electrical Circuit
They say that most people greatly fear public speaking. In fact, they say it comes in second only to death for what people fear most.
That's not me.
My idea of a really great time is a room full of folks who don't know much about controls or electricity. I show them how circuits go together. I can see lights snapping on - in people's heads and on the demo boards. And I'm possibly glowing more than any light bulb because of my delight in the learning going on there.
But I tell you, recently I was really nervous about an electricity class. I have three major tools: a battery-powered pink plush pig, a collection of homemade you-wire-'em-up electricity demo boards, and a projector to show my slides. I thought any class was absolutely dependent upon these three things - plus the people, of course. Not having these tools would be like, well, trying to eat spaghetti without a fork. How would I even begin?
As you may expect by now, I had an opportunity to find out. What I learned is that you don't need any pictures or diagrams to teach electricity when you have people. Folks learn about circuits better and faster when they or their buddies are playing the parts of the circuit.
I had thought everyone hates group role-playing. I was sure that techies hate it worse than anyone else. It turns out that techies love being a transformer, or a thermostat, or best of all, a valve. Oh, yeah! I've done it with four classes now, and it works.
Learning As A GroupI learned this when the slide projector didn't show up for class. Sometimes I bring my own, but more often the projector comes with the training room. This time it didn't. Eventually it was clear that it wasn't going to. And the class had to happen anyway. That meant I couldn't show any slides. What was I going to do, pass them around the room?
Of course I could have drawn circuit diagrams on the board at the front of the room. But I know that if I turn my back to draw, the Back Row Boys settle in for a nap. Can't have that. I'm gonna use those boys.
We were well into the class. I'd already explained that a circuit is always made up of a power supply, a switch and a load, and that they all have to be connected together in roughly a circle.
“Hey, let's build a circuit,” I announced. “Who wants to be a power supply? You?” I looked at the fellow who had asked at the beginning of the class if we were going to talk about transformers. He nodded.
“C'mon up here then. Stand, uh, how about here? You're a transformer - a power supply. In low-voltage circuits the power supply is a transformer.” I pulled one out of my supply box and handed it to him.
“Here's your transformer.” He took it.
“Now, who wants to be a switch?” I looked at a skinny kid in the back row. He grinned, looked at his buddy, shrugged, and loped to the front of the room. I handed him a thermostat.
“Like we said earlier, a thermostat is a switch, right?”
“Uh ... right.”
“Let's have you here beside the transformer. Now we need some connectors.” From the supply box I pulled out a handful of colorful insulated wires with alligator clips on both ends.
“Let's use these alligator clips. Connect the transformer and the thermostat together.”
With considerable fuss, the three of us got it done.
“So, what else do we need?” I asked, looking at the class.
“A load,” someone said.
“Who wants to be a load?”
“He does,” laughed two guys sitting on either side of a fellow with muscles enough for two people.
He shot a glare at each of them, paused, and slowly stood up. He lumbered to the front of the room and crossed his huge arms. I was betting on lots of tattoos under that work shirt.
He took his place beside the thermostat.
“This valve's for you,” I said, looking way up at his broad face. “A valve is a load. It uses electricity to open the valve.”
“Thanks,” he grunted.
To him and the thermostat kid I said, “Here are your alligator clips. You two go ahead and connect the thermostat and the valve together.”
Eventually they did.
“Do we have a complete circuit?” I asked the class.
I heard a tentative, “Yeah.”
I heard a stronger, “No.”
I heard, “Ya gotta finish the circuit.”
“We have the three parts of the circuit,” I said. “What do we need to make it a complete circuit?”
“Well, yes, more alligator clips. What are we going to do with them?”
“Connect the valve with the transformer,” someone said.
It was then evident what had to happen. The transformer and the valve had to move toward each other, in front of the thermostat, in order to make the connection. There were snickers from the performers' buddies. I heard “paybacks!” from someone in the circuit. Slowly the three parts of the circuit moved into a circle.
And it was then clear, as it never could have been with a picture, how a circuit goes together.
More Human CircuitsA few weeks later I was teaching a similar class. I had everything I needed, including my choice of projectors. I used my slides, but when we got to the complete circuit, it just wasn't as much fun as it had been with real guys playing the parts. Clearly it was time for volunteers to come to the front of the room to be a transformer, a thermostat and a valve.
Since it went so well, I decided to take it further.
“Do we usually have just one zone valve in a hydronics system?” I asked, looking at our human circuit in the front of the room.
“No,” someone answered.
“Then let's add another zone valve to this circuit. When we add a valve, we need to add another thermostat to control it. Let's have a couple more volunteers.”
This time, because everyone was having fun, including the guys at the front of the room, volunteers came eagerly. We figured out who was the thermostat and who was the valve.
I said, “Notice I didn't ask for a power supply. We're going to use the transformer that we already have up here. When more than one load share a power supply in the pattern I'm going to show you, it's called a parallel circuit.
“Second valve and second thermostat, let's wire you together. Now finish your circle with the transformer.”
Of course there was a lot of shuffling around while the two valves and two thermostats figured out how they could all connect with the transformer.
“Think of it like this: we want to have two circuits of thermostat, valve and transformer. But you both use the same transformer.
“It doesn't matter what shape you circuits are in,” I said. “You can have one circuit to the right of the transformer and one to the left. Or you can have the second circuit circle around the outside of the first. Electricity doesn't care. All that matters is that there's a path for electricity to leave the transformer, go separately through each valve and each thermostat, and get back to the transformer.”
With lots of laughing and horseplay, they did it.
From there we went on to figuring out how many of these circuits you can put on a transformer.
At the end of the class an old-timer came up to me.
“You know,” he said, “I have no idea how many classes I've been to in my life. But I gotta say, that was the best way to explain circuits I've ever seen.”