Chapter 4 - Exercise 23 Update

Someone please double-check me on this, but I hit a roadblock this week when I realized I didn't have any of the 1N4148 signal diodes specified on page 214. I went back to my shopping list but couldn't find that I'd ever ordered them... I checked all the chapters' shopping lists, but didn't find this particular diode listed. Again, this may be spelled out in glaringly obvious large letters somewhere, but I don't have them in my parts pack, so I had to order them...

... and they haven't arrived yet. I didn't want to make a special drive to ACK for these but it's looking like I'm going to have to do so if they don't arrive by tomorrow.

So, apologies for the lack of posts, but as soon as I can get my hand on these diodes, I've got the rest of the circuit already breadboarded and ready to go.

If this is an oversight on my part, please tell me where they are specified... and apologies in advance to Charles if I'm just plain losing my mind.

Chapter 4 - Exercise 23 Part 1

I had to really squint to find my 7492 chip - the writing on this particular chip was so small I used my magnifying glass... not kidding.

I've read over the entire experiment and I understand how it's going to develop... so I started by building the first simple circuit. Don't make my mistake and wire it up with standard LEDs... I thought I had mixed in the special Kingston LEDs I ordered from Mouser with my standard LEDs...a bit of digging through the clutter after a few swapped out standard LEDs (small 3mm red that look like the Kingston LEDs) didn't work and I found a small bag with 10 3mm Kingston LEDs in it... put them in and... it worked.

I've included a video here showing it counting from 0 to 5 (binary)... I reordered the LEDs a little different than the one in the schematic so I could see them lighting up vertically.

Have a great weekend, everyone!

Spring Cleaning!!

As you can see from this photo, my work area has become a hazard area... looking ahead to Chapter 5, I can see a section devoted to getting one's work area organized... I'm going to be moving my electronics work area to the basement (in workshop #1) versus the garage (workshop #2)... I'm going to try and find an inexpensive desk at Goodwill so I can have a place to sit down versus standing... which is how most of my workshop is structured for...

I've also been collecting a few electronics projects here and there to start on once I'm done with the book... not sure if I'll post those at this blog or not - what do you think? Having a dedicated area will be nice... and getting my office back to normal will also be a welcome sight.

Chapter 4 - Exercise 22 - Completed

Exercise 22 is fairly short, but I can see a lot of uses for the ability to use a NAND or NOR chip to flip back and forth between states and keeping power applied to one or another part of a circuit.

The first video below shows my results with the 7402 NOR chip. The second video is with the 7400 NAND chip. The only differences between the two is how the pull-up (or pull-down) 10k resistors are wired into the circuit and the SPDT switch (whether it's pole goes to positive or negative voltage).

A fun little exercise - be sure to use low current LEDs as the author suggests. I think I used mine although I made a mistake of not organizing all my LEDs I've collected over the various experiments and they're all mixed together... oops.

Chapter 4 - Exercise 21 - Completed

One thing I'm certainly learning through this process is that no matter how many times you check and double-check your circuit, you've missed something... that is, until it works. The author does a good job of warning us about accidental damage to many components, and my first thought is always "must be a faulty component" - I need to change that to "must be a faulty human."

The good news, for me, however, is two fold - one, my regulator wasn't damaged. But two, the 7432 chip WAS damaged. But the question is whether that damage came about because of my faulty wiring - I'll likely never know, but when I switched out my 7432 (after finding a wiring error - more on that shortly), it started working.

If you look at my picture closely, you'll notice a few differences in the circuit I built and the one on page 210. First, I didn't have a .33 capacitor, so I substituted a 2.2. I tested this before building the circuit and was able to determine that it didn't have any effect on the 5V regulated voltage...

Next, I didn't have two of the 0.01 capacitors so I took a chance and substituted two .047 capacitors for each... I wired them in parallel (opposite of resistors - parallel you add their values) and crossed my fingers that this substitution was okay.

Now - for the faulty wiring. Figure 4-95 on page 210 is fairly easy to follow... but don't make the mistake I did. I had that 10K resistor at the bottom going into the negative column, not the positive. Could that have damaged the 7432 chip? Who knows, but after catching and fixing this error, the circuit didn't work. I went back... carefully checked off each wire in Figure 4-95 and verified I had no shorts and that all wires were done correctly. They were (hopefully).

So next I wondered if it might be a faulty chip - luckily I started with the 7432 instead of the 555 chips... as soon as I replaced the single 7432 with a new one, circuit worked. I pulled it out, put in the old one (same orientation) and the circuit didn't work. Put in the new one... circuit worked. Hmmm... how about that?

I'm including a video below showing the circuit working... I actually soldered wires to my S1 because I couldn't get good connectivity by just twisting the wires into the ends.

So, many lessons learned... again. Check my wiring. It's likely MY fault, not a component. I really am not rushing these builds, but I guess I need to slow down even more... the errors are easily corrected... but also easily avoided if I put a little more effort into slowing down and verifying all my wiring first... I hope my readers are learning from my mistakes and avoiding the frustrations I'm encountering.

Chapter 4 - Experiment 21 - Failed Regulator?

I had such a great start with the book that I think all the gremlins are now starting to appear... I've got the circuit for Exercise 21 wired up but I'm not getting any voltage on the breadboard. I've taken multimeter readings of my AC adapter... 9 volts there. I've checked all my wiring... so now I'm beginning to wonder if I may have damaged the 5V regulator somehow? Anyone know how sensitive or rugged these little devices are? I've only got one, so I have no way of testing it.

I replaced the two capacitors as well... but no luck. I took a voltage reading across the larger capacitor (.33 in the book but I substituted a 2.2)... it barely reads 1V.

Any ideas? I really can't move forward either since a few of the remaining exercises rely on the 5V regulated voltage setup.

Chapter 4 Experiment 20 - Time to Move On

Okay, so I took some time away from this experiment, hoping that I'd be able to come back, find my mistakes, and get this circuit working. Well... no luck. But I'd like to try and explain a few things I did differently this time and a few things I was able to verify about the circuit - maybe this will help someone else trying to get this crazy thing working.

First, I totally rewired the entire thing. I found two errors in my wiring on the first try. This time around, I wired up each chip, double and triple-checked the wiring before moving on to the next chip. This worked well, and I was able to get the * button working and lighting up the LED.

After completing the wiring, the # sign would work and light up the LED... but this time I couldn't get the * button to light up - I took a voltage reading - I was only reading 1.0 volt across the LED - I tried different LEDs but no luck. I also tested my LEDs as the # button LED and they worked, so they obviously weren't burned out. My only thought is that they're simply not getting enough voltage. I think I'm using low voltage LEDs but I may be wrong. Either way, why would it initially light up but now now? And it doesn't matter anyway - even if the LED doesn't light up, pressing the * sends current to pin 8 on the 7408 chip, turning it on. The LED is just a visual cue.

Okay, so scratch that... next thing I wanted to figure out what whether the 555 chip was sending any voltage to the LED when the * button is pressed... remember, you have to hold down the * button while entering the code... when I pressed the * button I got a 0.47 volts reading on my multimeter. But isn't pin 3 only supposed to send a pulse if voltage is dropped on pin 2? If I'm detecting voltage on pin 3, this would mean that the 7408 is sending a 1 to pin 3 on the 7404 (a NOT operation) which in turn sends a 0 (no voltage) to pin 2 on the 555 chip. Which means I'm entering the code correctly... so why isn't the LED lighting up? One of the pics shows me using my multimeter and getting a voltage of 0 on pin 3... I didn't have enough hands to hold down *, enter code, snap picture, and hold the probes... argh... so you'll just have to trust me that I got the .47 volts on pin 3...

Oh, well... I gave it a second try, but I think it's time to move on to Exercise 21.

Oh, and there's an unlabeled resistor in Figure 4-84 (I'll submit to errata if it hasn't already been done) - I think it's supposed to be a 10K to match the 10K resistors for the 1 keypad button and the 4 keypad button... I may be wrong.

So, this concludes my attempt at Exercise 20. When I'm done with the book, I may come back and give it one more try... because I hate to leave an exercise with doubts. Is it working? I think so... but I can't get an LED to verify... but I do get positive voltage on pin 3 when I hold down * and press 1, 4, then 7.

So... this leads me to my next contest. I'd like to reward a Maker's Notebook to the first reader who can upload a video showing this circuit working in all its glory... it doesn't have to be mounted to a computer, but it should show all the LEDs working as desired - it should show an improper code being entered as well as the correct code and all the LEDs lighting up as they should - especially the * sign as you hold it down and the UNLOCK LED when the code is entered. First person to post a video that clearly demonstrates the circuit working gets the Maker's Notebook. (Sorry, Charles - as the author, you're prohibited from entering the contest... )

I've got a few videos below to finish up and then it's on to Exercise 21... thanks for sticking with me folks - got a bit behind in "real world" work and had some family business that had to be attended to... but I'm caught up and ready to get back on track.

Components Pack 1

So, I got my hands on the Make: Electronics Components Pack 1. In my best Vader voice - "Impressive."

First off, the case - hands down, this is one of the nicest storage containers I've ever seen. I've asked MakerSHED to consider selling these individually - they're that nice. (If you agree, add your voice to mine and email MakerSHED and ask them to put them up for sale.)

The pack comes with an inventory sheet, complete with labels for the individual bins and what you'll find inside them. As you can see, this thing is packed - over 350 pieces. I really do NOT want to add up the cost of all the items I purchased that are found in this kit - for $99.00, I'm sure it'll make me cry a bit. Big man-sized tears. If you are serious about following through the book and performing the experiments for Chapters 1 and 2, you'll save a bundle by buying this pre-loaded components pack.

The bottom portion of the case holds many of the larger items - spools of wire, breadboard, AC adapter, and more. The kit even comes with pre-trimmed patch wire - with heavy 22 or 20 gauge end tips exposed. I wish I'd had these when I started! You also get a whole bunch of patch cables (with gator clips on end) - way more than I purchased initially. It looks like the team at MakerSHED really put some thought into what to include that would make the reader's experiences better.

The top portion of the case contains all the smaller bits and pieces -resistors, potentiometers, capacitors, and more. There's even an X-acto knife for trimming away the walls of the spare relay - YES, they included a spare relay just as Chapter 2, Experiment 7 requires!

You've got fuses, batteries, battery holders, those crazy-difficult-hard-to-find 6027 programmable unijunction transistors, and a whole slew of LEDs.

(And for those who pre-ordered, they've thrown in some extras that you'll enjoy... )

The first thing I thought of when I inventoried my kit was how easy this is going to be for me, as a parent, to introduce my son to electronics one day... (if he's interested). Then I realized that, if I were a teacher, this would be something to recommend to those students (and their parents) who show an interest in electronics. Finally, I realized how easy MakerSHED has made it to organize classes around this material - we've got the book and now the components kits - I have a feeling we'll be hearing about "Make: Electronics" classes popping up soon.

If you've ordered the kit, let us know your own thoughts on the pack. And when I get my hands on Pack 2, I'll be sure to let you know my initial thoughts as well...

A slight pause

I'm heading out of town for a few days... I'm really behind on my "real world" work, let alone getting my exercises done for this book. I need a mental break anyway, so I'll get started again next week... just got a lot on my plate this week and next... but stick with me... I WILL FINISH this book!

Chapter 4 - Exercise 20

Well, I wired it up... tested it out... no luck. A few parts of the circuit work (such as the Power On LED and the keypad) but not really sure what's going on. As you can see, I didn't spend a lot of time keeping my wiring clean... it's ugly.

Even so, I double and triple checked my wiring and I think I got it all correct. My relay still hasn't arrived so I worked around it by inserting two pushbuttons (lower half of breadboard). I hold down one and that simulates the lower part of the relay being closed... releasing it and pressing the other button simulates the upper portion of the relay being closed.

At this point, I'm willing to go over it one more time (tonight) but I'm ready to move on to Experiment 21. I'll try and come back to this circuit when my relay arrives, but I've been stuck on Exp20 for a bit and am a little tired of it. My goal was to work through all the experiments... and hopefully have them all work. I want a 100% success rate, so I'll likely come back to this one on a weekend when I have some time. (And time is the limiting factor right now - I've got a new book contract that's starting up AND I'm finishing up the editing on another book and that's taking ALL my daylight hours it seems. Alright, enough complaining...)

If anyone has a good clear photo of their breadboard with Exercise 20 all wired up or even a video, let me know... I'd at least like to see if there's anything glaringly obvious that I've done wrong.

Chapter 4 - Exercise 20 Relay

I decided to cut open the dead relay I had purchased a while back (dead because any voltage applied to it doesn't seem to make the relay click)...

The top-down view is the one that I can best explain. See that white piece of plastic shaped like a T? From the picture's POV, pushing on the top arm of the relay pushes against the piece of plastic and that, in turn, pushes on the second relay arm (on the bottom). But it doesn't work in both directions... pushing on the bottom arm does not move the plastic and the top arm stays where it is... so I've just got to think this through and figure out how this relay works with respect to the circuit I'm building.

Chime in here, folks... it's been a long week and my brain's not firing on all cylinders. Anyone care to take a stab at explaining how this little relay works?

And by the way... the description for this relay is dual coil... is the 2nd coil inside the outer one?

Chapter 4 - Exercise 20 Update 2

Let me tell you - soldering up the keypad with the ribbon cable is tedious... frustrating... nerve-wracking... and somewhat fun. It looks very Frankenstein-ish and my multimeter tells me all the wires survived the soldering... one or two slight singes as I was putting on shrink wrap, but if I find a wire is bad, I can always make that one of the un-used code numbers, right?

The hard part (for me, at least) is soldering a 22 gauge solid core wire to a 24 gauge stranded wire... hard to make them stay together. Anyone have any suggestions?

Since I'm not going to cut into my wife's PC tower, I think I've come up with a possible variation of this, suggested by the author's text. I think it might be fun to build a box for my son that uses a combination of Exercise 20 and maybe Exercise 11. I could build a noise maker circuit and have it triggered if the code isn't entered properly... or maybe implement the magnetic switches for the alarm system into the box... if the lid is opened without the proper code, the magnetic switch is broken and the alarm sounds. I'll have to think about that...

So, while I wait for my replacement dual coil relay, I'll start wiring up the breadboard for testing...

Also, I had to hunt down the Panasonic DS2E-SL2-DC5V data sheet to understand what's going on inside... here's a link in case you're interested. Page 6 is what you're looking for, DS (2 Form C). I'm still trying to figure out how this thing works, so please chime in if you have an explanation... the more the merrier.

UPDATE: I just created a small circuit with a single LED - I plugged in the wire for pin1 (COM) to positive voltage... and connected the the LED to negative voltage. I then stuck each wire (except for pin 2 which doesn't have a function) into the positive side of the LED, pressed its corresponding button, and hoped it lit up. It lit up for each and every wire. So my soldering worked and the keypad works as desired. That made me happy. Video added below.

Chapter 4 - Exercise 20 Update

After searching (calling, actually) everywhere in Atlanta, it appears that no one (Radio Shack or ACK Supply) seems to carry the DPDT dual coil latching relay. Argh.

So, I've ordered it from Mouser. But I've got a gripe with Mouser... they do not provide a shipping price until they've actually shipped the order. So I have no real way of knowing what UPS ground is going to cost except for their rough estimate. I'm sure that estimate will be close, but it would be nice to have an actual shipping cost as part of the order before clicking the Submit button. Oh, well.

I've got to solder up that wire ribbon to the numeric keypad today... should take some time as the wires are very tiny and easy to tear.

Chapter 4 - Exercise 20 - Number Pad

Apologies for the delay in posting... I've got quite a bit of work piled up from a trip out of town and am trying to catch up. Exercise 20 is going to be a multi-part project as I've not been able to find a DPDT dual coil relay locally...

In preparation for the exercise, I purchased an IDE cable (for a hard drive) for $6.00 and cut it so it has 17 wires (14 for the keypad and 3 extra in case I mess up soldering or cut a wire accidentally).



This is tedious - you have to be very careful with the cable because it's so easy to rip a single wire.
I used an X-acto knife to cut each wire apart (except for the 3 spare wires).
I stripped off 1/4" from each end - one end will connect to the 14 solder spots on the keypad... the other end is where I'll solder solid core wire (maybe 1" or 2" strands) so I can use it with the breadboard. As it is, the wire is simply too thin to insert into a breadboard. Once I pick my code, I can save some wire by joining 3 or 4 of the keys not used in the code and then soldering them to a single solid core wire. I don't think I'll be able to solder all 11 unused wires (14 - 3 for code) to a single strand.

I also don't have a spare computer to cut apart and mount this thing - I have 2 laptops and I don't think my wife will agree to let me experiment with her desktop computer.

Now to go find a DPDT dual coil relay...