Tuesday, May 27, 2014

Experiment 0 (Preface): I Have The POWER!

Multimeter reading 4.91 volts -- close enough to 5V for me to be happy.
Today I wired up the schematic from Figure S-2 (page xxvi of the Preface) on one of my new breadboards. I didn't make it all pretty like the one that Charles wired up for Figure S-1, but I'll probably clean it up a bit once I get a simple problem solved (more on that in a moment), but as you can see here, it does deliver almost 5V (4.9V give or take).

My 5VDC regulated power supply is now working... but it doesn't look exactly like the one in Figure S-2. First, I didn't have a 0.33 microfarad capacitor. (Actually, I probably do, but sometime in the past my nice organized capacitor collection became disorganized. I'm not going to point fingers at either the 7 or 4 year old boys in my household, but I'm certainly looking in their direction.)

Closeup of 5V DC Regulated Power Supply
To solve this, I went back and refreshed my memory on combining capacitors. I seem to recall that putting capacitors in parallel (versus series) was the way you added their values together. I sure hope this is true, because that's exactly what I did. I put a 0.1 microfarad and a 0.22 microfarad in parallel and no puffs of smoke have appeared.

As with Figure S-2, I added in a green LED but the more I think about it a red LED is more likely to make someone think *DANGER* so I'll swap that out later. I had plenty of 2.2k resistors in my collection as well.

Teeny tiny switch -- $0.95US
One other difference in my power supply is the On/Off switch. Charles uses what appears to be a SPDT switch but I could not find the PC-mount type to save my life. Radio Shack didn't have it, and even my trusty Atlanta-based ACK Electronics store was coming up blank until one of the associates there pulled out this little gem of a switch -- it has the low profile of a simple pushbutton component and inserted quite easily into the breadboard. Total cost -- $0.95US.

I'm not using a 9V battery. Instead, I pulled out the variable wall wart I purchased back when I was working through Make: Electronics. The ends are stripped and I soldered on a piece of red wire and black wire and added some shrink wrap to identify the leads. Those go into the breadboard as shown in Figure S-1 and after double-checking my wiring... I flipped the little power switch. The LED began to glow and no smoke was seen coming from either capacitor. (Remember: if you're using capacitors that actually have polarity, wire them up the right way -- the black stripe on the side goes towards GND.)

Here's the video describing my setup:

If you've watched the video, you now see my slight problem. The breadboard doesn't have voltage continuity down the left or right side. Maybe this breadboard requires jumper wire to connect the power and GND lines, but since the breadboard came with no documentation the only way for me to be sure is to open one up. I'm going to test this problem with the other two breadboards -- if they have a continuous power and GND line, I'll cut this first one open and share a photo of its guts in a later post.

Reading 0V when jumper wires moved down a bit.
One final observation I'd like to make about this new breadboard -- the holes are tight! Inserting jumper wires and components was tricky, and a few bent posts required a pair of pliers to fix. While I like the idea of this breadboard and how it matches some perfboard, if I continue to have these issues inserting components and wire I may very well switch back to the old standard. I'm going to give these new breadboards a few tries before making a final call.

My next tasks are transferring this wiring to a new breadboard (or two) to test the continuity of the power and GND lines as well as the ability to easily insert wires and components PLUS testing out Experiment 1.

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