Thursday, May 27, 2010

Special Project

To quote Chris Knight - "It's yet another in a long series of diversions in an attempt to avoid responsibility."

Rather than pull my hair out (because I kinda like having it) I'm taking a very short break from the book to try my hand at an electronics project that is easy to follow and understand from what I've learned from Make: Electronics... here's the story:

My 3 year old son has discovered... MONSTERS! We've tried to assure him they're not under the bed or in the closet, but he has these moments where he's certain they're around the corner... we've tried to assure them there's no such thing... but he's 3! He probably DOES see them with that imagination of his... so...

I've decided to empower him. No longer will monsters be allowed in our house! As long as he has his trusty Monster-B-Gone with him, all is well.

The Monster-B-Gone is my simple little project involving 6 LEDs moving like the traditional cylon or KITT the super car. Back and forth... back and forth. With the push of a button, my son can banish monsters because, as we all know... monsters HATE the color green! One push of the button and they're off and running! I've already started talking to him about the hows and whys of the animosity between monsters and the color green. I think he's buying it... this should work for a bit and give me time to work on the next solution.

I've based my circuit on the Cylon Pumpkin... if you want to build the same circuit, I've consolidated the author's circuit drawings into a single PDF file you can download here. As you can see from the video, it works fine. I'll be transferring everything to a small project box with a momentary button on the top or side so the batteries aren't being constantly drained. More later as I get the soldering moving forward...

I promise I'm NOT done with the book or the projects... just need to think about something other than Experiment 29 for now...

Monday, May 24, 2010

Chapter 5 - Exercise 29 Update

Well, I don't know... I've tried quite a few things. First, I replaced the wire to the speaker with a high gauge wire (thinner and twisted, not solid core) because I was worried maybe not enough power was being generated. No luck. I also replaced the TEA chip and a few capacitors (didn't have enough of each size to replace them all) but that doesn't seem to have helped either.

Next, I took a look at the adapter. I thought - okay, maybe the adapter just isn't functioning... but no, it works. I used it with some patch cords to connect to a small radio with the right plugs and my iPod played music just fine. So something is wrong with my circuit.

Based on past experiences with this book's exercises, I knew it had to be operator error. Something small and simple to overlook... but I checked all my resistor values, checked where every wire was going (positive or negative voltage), double and triple checked ever TEA chip pin to make sure they were all wired properly and none were ignored... and I'm getting zip.

Is it possible that the iPod via the adapter via the breadboard just cannot power this 8" speaker? Suggestions welcome, but I'm probably going to go ahead and ship to exercise 31 and leave this one alone... I don't have to take it apart for exercise 31, so I'll give it a break and see if a light appears in the sky with the answer.


Wednesday, May 19, 2010

Chapter 5 - Exercise 29 part 3

Okay, I'm still having trouble with experiment 29. I'm including some close-up photos here, hoping that someone may catch an error or see something that I'm not doing properly.

A few things - the schematic on page 251 (Figure 5-41) shows the hookup wire and the 10 microfarad components wired up in series but with a set of pushbuttons used to isolate them. I thought this might be the issue early on so you'll see that I've only got the hookup wire in the circuit... I figure if I can get the sound working with the hookup wire, then I'll pull it out and insert the capacitor.

Other than that, I believe I've wired up the circuit as seen in Fig 5-41. I've verified all my capacitors and resistors for their values... the TEA2025B chip is inserted with the proper orientation... and I've got the 100 microfarad smoothing capacitor between the voltage inputs. The headphone jack is the only other questionable issue that I'm not sure how to test... I taped the wire inserted into the one socket as well as the one connected to the outer metal surface of the other socket...

One question, though - I used solid core 22 gauge wire for the speaker. I'm wondering if that wire is too "heavy" for this experiment.

Any advice is welcome... I'm not wanting to get bogged down on this experiment but experiment 30 builds on it... so if I can't get it working soon, I'll have to skip 30 and jump to experiment 31. If anyone has successfully completed this experiment with solid results, please let me know, as well. If I can't get it working, I'd at least like to get a video of an actual working project.

Friday, May 14, 2010

Chapter 5 - Exercise 29 part 2

I got everything hooked up and I double-checked the schematic for all the resistors, capacitors, and pins on the chip. I chose to use my iPod with the $5.99 adapter I purchased from Radio Shack.

I also got the speaker built - it's ugly as it can be but it's bolted to the plastic box and yes... those are Mickey Mouse diapers in the bottom. We use what we can... my son is in pull-ups now, so I don't think he'll mind.

I decided to video the first power up... you can see that below.

Thursday, May 13, 2010

Chapter 5 - Exercise 29

Apologies for delays in posting recently - throw in a small bit of procrastination with my mistakes in ordering incorrect components and ... you get the picture.

I got most of the schematic on page 251 wired up - it's a variety of colors, isn't it? I do believe there are a couple of mistakes here, but I'm not going to post them to the errata page until I get confirmation from a reader or from the author.

On page 251, for example, the 100microfarad smoothing capacitor for the 9V has the symbol of a nonpolarized capacitor, but the text says to use a regular electrolytic. I'm going with the text because of the author's explanation for WHY to use that type of capacitor...

Also, the 0.15microfarad capacitors are shown as NP type but not labeled as such... here, I'm going with the NP variety (that's all I have anyway) because of the symbol. Also, please note that that 0.15microfarad capacitors are not specified in the shopping list... I don't have any from previous experiments in the book, so I had to grab some of these locally.

I shot the photographs here before writing this up, so I also just noticed a mistake I made - the NP capacitor sharing the top part of the circuit with the coil is a 10 microfarad, not 100 as I've put in my circuit... fortunately, I haven't powered mine up yet... more on that in a moment.

I'm also wanting confirmation on something in the schematic - the 100microf coming out of pin 6 goes into pin 1... not connected to negative voltage as the other two 100 microf on pins 8 and 11. These are HUGE capacitors, and I'm very nervous about powering up this thing until I get that resolved as well... my initial thought was that that capacitor on pin 6 should at least have a connection to negative voltage, but maybe pin 1 is initially negative (a sink?)... again, not sure so I'm not powering up this bad boy just yet...

I've also got to pick up a headphone socket like the one in Figure 5-42 as well as some hardware to mount my 5" speaker to the plastic box. Will do that today.

We hear so much about audio and video equipment and the high voltages and currents they use/produce... so I hope you can understand my nervousness about plugging this breadboard in until I have all of these details ironed out... don't want a burned breadboard or any exploding capacitors in my vicinity... even with eyeshields on.

Monday, May 10, 2010

Experiments 29 and 30

Experiment 30 builds on Experiment 29 - unfortunately, I've had some bad luck getting the proper components for these 2 exercises. Exp 29 calls for 100 microfarad capacitors of the nonpolarized electrolytic type... ditto for 47 microfarad. I thought I'd ordered the proper BP type capacitors... apparently not.

One thing I did notice about Experiment 29 was that it calls for two 47 microfarad capacitors but they're not seen in the actual schematic on page 251. I do see in the schematic two 0.15 microfarad capacitors... I don't have those either... added to the shopping list. You'll also see a 10 microfarad NP capacitor that's not listed in the experiment's shopping list... argh.

I've called ACK supply and I believe I can get the right components this week, but I'm not driving to that part of town until Wednesday... so Exp 29 and 30 are on hold temporarily. (In the meantime, I've read over Experiment 31 and believe I can go ahead with that one while trying to get the capacitors.)

I'll also need to pick up the headphone socket seen in Figure 5-42 - this isn't on the shopping list either. Thankfully, I purchased one of those big bags of resistors so I've got those covered, including the TEA2025B chip required. Again, sorry for delays, but I'll get back to these two experiments soon.

On to Experiment 31...