Recently I’ve seen a number of sites discuss the Panavise. Specifically, which is best for the beginner? Here is my executive summary:

If you are starting out with electronics you only need one, and it’s this one: The Panavise Jr.

PanaVise Model 201

It’s cheap (< $20), it opens pretty wide (2.8 inches), it rotates all over the place, and it has slots for holding printed circuit boards. I have yet to meet a basic electronics kit PCB that doesn’t fit into it.

If you need to work with bigger boards on a regular basis, your next purchase would be the 305 Multi-Purpose Center:

PanaVise 350 Multi-Purpose Work Center

It’s about $55 and has a gigantic (9″) opening.

My least useful Panavise? The 301 Standard / 381 Standard With Vac. It’s a good vise, but really crappy for holding circuit boards.

I use the Jr. 80% of the time, the 305 about 10% of the time, and all my others (381, 333) the remaining 10%.

Long story short, if you are doing electronics, get the Jr and then get the 305. You’ll be happy. Toss in a 301/381 is you also need a more traditional vise.

I’m not often impressed with new gadgets, but I find the iPad to be the most interesting thing I’ve seen in a long time.

This may seem odd, given the amazing amount of negativity that seemed to surround the product release. Such as:

• “It’s just a big iPod Touch.”
• “I’d never get it, I have an iPhone.”
• “I have a netbook that’s a ton cheaper.”
• “You can get good laptops at this price.”
• “It won’t sync with Linux.”
• “It’s proprietary.”
• “It doesn’t play Flash [this often coming from the Linux people--LOL]“.
• “It’s something my grandma would use.”

and so on. Maybe I’m the one out of touch, but I can see a ton of uses for the device.

I don’t know about you, but it’s 2010 and I’m tired of complicated installations, .NET framework upgrades, and compiling C source code — just to get a silly little application running. An app store where I can download applications which have been certified and tested? A single place to get that stuff? Sign me up. This will be a huge boon for people who are sick of dicking around with computers (me) and people who need a reliable, safe, environment to work in (my parents).

I can really see this as the perfect bedtime & relaxation device. How many times have I been in bed wanting to add something to my Netflix queue? Lots. So I lean over, grab the X61, open it up, wait for it to wake up, re-connect to the network, open a browser, go to Netflix. Not the end of the world, to be sure, but an unnecessary hassle.

And what about when I just want to browse though some old woodworking magazines on Google Books? I don’t need a keyboard, I just need a slate that gets me to the magazine so I can page through it, bookmark interesting parts, and then put it down. There are a lot of times I just want to browse information without dealing with a full blown laptop/netbook.

Am I going to write blog posts on it? Nope. Why would I? I’d sit at my desk to do that. Do I need it to take photos? Well, do I normally take photos with a netbook? Nope. I’d use a real camera, or a camera phone (if I had one).

Take a moment to think about your REAL interaction with your computer. For me, 90% of it is reading/viewing content. I skim though 100 or so blogs in Reader. Check e-mail, rarely responding (unless it’s work). Check FaceBook. Read some back issues of magazines on Books. Check on my business sites (seeing what traffic is going where, checking on ads, checking on the store). Skimming Netflix and updating queues. Reading the news. It’s all checking and reading and viewing. The iPad would do all of that brilliantly.

If Douglas Adams were alive he would instantly recognize the iPad as THE Hitchhiker’s Guide To The Galaxy.

We’ve completed three new Sixty Second Shop videos. It’s been a while, but we’re back on track. They focus on our Electronics Workbench setup.

YouTube Link: SSS Videos

Site Link: Sixty Second Shop

Here are a few photos of the inside of this little light.

First, you can see that the bottom is carved out. I used a big (1 1/4″) spade bit to drill out the space for the wires and battery. BE CAREFUL. It can throw the wood right at you. Use a clamp and a full face plastic face mask. (I’ve had more than one piece of wood try to rip my hands off / poke my eye out.)

The brass tube which supports the bulb is toward the left (it’s “potted” in some Liquid Nails). The power goes up through a thin wire (a wire-wrap gauge) up to the lamp. The brass tube itself is the ground, meaning we only need one wire going up. (It’s low voltage — 9 V — so it’s safe.)

The button is toward the right. The battery nestles in between:

Here is the magic part of this project:

The brass tube comes up through a small hole in the bottom of the bulb base. It’s soldered into place at the bottom. It pops through about an inch or so, to which I soldered a current drop resistor. With the brass soldering work done, I installed the LED. It’s a 10 mm white LED. One lead is soldered to the wire wrap gauge wire fed through the brass tube. The other lead is soldered to the resistor. Some heat shrink was used to keep things from shorting out.

The key is the bulb. It’s not a real light bulb. A while back I found some very realistic looking clear light bulbs at Hobby Lobby. They are perfect for projects like this, and much safer — the glass is nice and thick. I spray painted the inside & outside to get a nice frosting effect (light coats, drying between each coat). The bulb is a little heavy, so make sure you carefully secure the brass tube in the base. Mine is a little bouncy, but not bad.

Here is the finished product, on our dusty & cluttered night stand:

After getting the Display Controller and Button Controller working, it was now time to work on the enclosure for the Shop Timer.

Since this is going to be in the shop (garage) I wanted something pretty heavy-duty. Since I have a lot of 1×4 material on hand, I built a simple box using it and the existing timer face (which is made of 5mm plywood). Here is the end result:

It’s about 13 3/4″ wide and 6″ tall. The corners are simple butt joints, held in place with two 1 1/4″ screws at each joint.

On the inside I fastened the display control board with a couple of small wood screws. I mounted the board on top (upside down) to avoid dust buildup on the board.

Since the control box needs to be sturdy and visible, I made it out of some more 1×4 lumber and painted it bright Halloween Orange.

Once the paint dried, I installed and soldered up the three arcade buttons. One each for: Start, Stop, and Reset. In this photo I’ve finished the soldering and crimped on the Molex connectors. The buttons are plugged into their controller board for testing.

Things tested out fine! No debounce problems and everything worked as expected (thank goodness).

With the circuit and buttons tested, it was now time to finish the assembly of the button control box. First I fastened on the back and then mounted the control board to it:

Note that I removed the bottom (right side) of the box and made a little notch in it — big enough to fit the control cable through. I looped the wires (they are braided and heat shrunk at intervals) through a toroid. The toroid prevents RF interference (unlikely) and provides some strain relief (much more likely). The board is fastened to the back using a couple of wood screws. The control box only has the data lines, power is being fed at the display (though the circuits are set up so that you can provide source power at either point).

Now all the buttons get connected via the Molex connectors:

Finally, everything gets stuffed into the box and the front cover gets screwed back into place:

You can see in the above photo that I have the back board overlapping a bit and a hole is drilled into it. That’s for hanging the controller around the shop.

After this was done I tested everything again. Still working!

Finally, I rigged up an old wall wart (a 5V one I had around — you can go to 15 V) and wired in a connector. So, I have the control lines and the power lines feeding into the display portion. The control lines then drop down to the button box.

Here’s the final unit, installed in the shop:

For now I’ve placed it above one of our shelving units — it’s right near the ceiling. The control box is sitting on one of the shelves (actually hanging from a screw I drove into one of my heavy-duty wooden book boxes).

It works like a charm and is in the middle of the shop, so it will be easy for either of us to us.

I was trying to get this mini-project complete before our out-of-town guest left, but things got busy.

This is called the “Uncle Fester” night light, in honor of the Addams Family character who was able to light a bulb by putting it in his mouth. My version will be battery operated and use a white LED inside a traditionally sized light bulb.

The bulb is held above the base by a thin (1/16″) brass tube, which also hides the (very small) wires.

After some experimentation with push buttons and toggle switches it became apparent that mechanical switches are way too electrically noisy to accurately control the CD4026 logic lines. Not horrible, but enough to frustrate me, and I don’t need to get more frustrated in the shop.

So I went looking for either a button debouncer of some sort (using a Schmitt trigger) or a toggle / latch or something. I looked at flip-flops, but didn’t want to mess with them. I knew there had to be an easier way. And, once again, the humble 555/556 timer comes to the rescue.

The 555/556 have been written about endlessly, so I won’t go into much detail. The key is that they can be wired up to clean single-shot pulses (needed for my “Reset” button) and can also be wired to act like a toggle — press one button and the output is “high”, press another button and the output is “low” — this is exactly what I need for the “Run/Stop” buttons.

Normally you’d need one 555 for the “Reset” functionality and another 555 for the “Run/Stop” toggle. I have a bunch of 556’s on hand — and they are basically two 555s on one chip — so I have exactly what I need (and a lower chip count).

Here is the circuit I used for the Toggle (”Run/Stop”) part of the button interface. Note that this is for a 555, if you use a 556 be sure to use the correct pins (set A)!

When “trigger” is pressed, the output is HIGH. This means that my CD4026 would go into Clock Inhibit mode, meaning that the display will “pause”. Then “reset” is pressed, the output is LOW, meaning that the CD4026 will be non-Clock Inhibited — so the display would “run”. Note that the “output” goes to the Clock Inhibit pin (#2) on CD4026 #1 — you only need to Inhibit the first chip in the chain. (I learned this yesterday.)

Here is the circuit I used for the single-shot “Reset” functionality. Again, if using a 556, use the correct pins (set B).

When you press “trigger” you get a single output pulse. The length of the pulse is dictated by the R1 and C1 combination. In my circuit I used an R1 of 3.3K Ohms (actual measured value: 3170 Ohms) and a C1 of 100 uF. This gives an approximate on-time of 0.34 seconds.

I did not include the “reset” button in mine, since I didn’t need it. However, I did keep the 10K pullup resistor on the reset line. The 10K on the trigger line is also a pullup. This means that when the button isn’t pressed the trigger line is held “high” (positive / Vs). When the button is pressed, the trigger line goes “low” (negative / ground).

Also, I didn’t add the cap on the control line. You’d put one there if you have interference. If I have room on the board I’ll probably solder it in, to be safe.

Both of those excellent diagrams come from a great source for basic electronics, The Electronics Club. They do an excellent job of explaining in simple language how the circuits work, and I’ve yet to find a problem with any of their work. Plus, I love their schematics.

The Electronics Club : 555/556 Sample Circuits

Now that I had my schematics I was ready to wire. Here is the finished result:

The chip in the center is the 556 timer (two 555 timers on one chip). The two 10K resistors on the lower left are the pull-ups for the Bistable toggle. The 10K resistor to the far lower right is the pull-up for the Reset line.

The resistor to the right of the chip (timer B) is a 3.3 K Ohm and the capacitor is 100 uF. This is the R/C combo used to determine the length of the single-shot pulse. It will be about 0.3 seconds in duration.

The capacitor at the top is a 100 uF across the power supply lines. This is a “smoothing capacitor” and recommended for 555 circuits. I learned that you sometimes get weird power supply behavior when the 555 is changing its output state (going low to high). I saw some of this with my CD4026s — they would increment a bit extra on ticks — but only intermittently. The 100 uF cap helps even out the supply problems. There is one on this board, and another on the display controller (which has a 555 as the timer / tick generator).

The three buttons (Start, Stop, and Reset) will be connected to the Molex connectors toward the bottom. When the buttons are pressed they will pull the appropriate lines down to ground. “Start” pulls the “A” reset line to ground. “Stop” pulls the “A” trigger line to ground. These two make up the start/stop toggle of the display. The “Reset” pulls the B trigger line to ground. (”A” refers to timer A on the 556. “B” is timer B on the other side of the chip.)

Finally, there are two other Molex connectors toward the top. On the left is a two pin for the power supply input. On the right is a four pin. This is what will connect the button controller board to the display controller board. You only need 4 wires for this: Red (power), Black (ground), and then Blue (reset) and Yellow (Clock Inhibit). The colors are arbitrary, but consistent through the design.

Power and Ground are obvious.

Reset is normally held Low, until the “Reset” button is pressed, at which point the monostable will fire a single shot High down the line and then return to Low.

When the “Start” button is pressed the Clock Inhibit line will be held Low. Shen the “Stop” button is pressed the Clock Inhibit line will be held High. This is a toggle.

I tested up everything last night and it worked pretty well. Today I need to wire up the three pushbuttons and put them in a case.

I’m pleased that I ended up with the three push button design. It’s very clean and I’ll be able to use my favorite button — the jumbo arcade buttons! Besides being big and cool, they also have the added benefit of being able to take a lot of abuse. This is critical for the shop work. (I was afraid that the sawdust would clog some of the smaller toggle switches I was considering.)

Here is a short video of the Shop Timer in action. During the later part of the video I placed a piece of translucent plastic in front of the LEDs.

I started the layout of the controller board last night, but needed to sleep on it a bit — so I could figure out how I wanted to handle start/stop/reset. This morning I had a better idea of how I’d handle it, and started wiring up the board. Here is the end result:

It is very similar to the board I built for the LED Christmas Tree. A 555 in the upper left handles the “ticks” and three CD4026 chips handle the 7 segment displays. You need one chip for each digit. Key differences between the two boards:

• One of the fixed resistors for the 555 timer has been replaced with a 100 K potentiometer. This will allow me to fine tune the ticks to get as close to a second as possible. The 10uF, 10K, 100K pot configuration gives me from about a quarter second up to about 2 seconds of delay / range.
• On the Christmas Tree the Clock Inhibit (pin 2) and Reset (pin 15) are permanently tied to ground. This means that the CD4026s always “listen” for 555 clock ticks and never reset to zero. Since I’m designing a timer, I want to be able to reset to zero easily (without power cycling) and also be able to “hold” the count. So, I bring the Clock Inhibit and Reset pins up to a Molex connector (upper right). This will be connected to a small controller box which will have the appropriate switches.
• This board uses cascading digits, so the chips are connected to easy other to support that. The chain goes like this: tick from 555 goes to CD4026 #1 Clock. #1 Carry Out goes to #2 Clock. #2 Carry out goes to #3 Clock. If you had more digits you would continue the chain (#3 Carry Out goes to #4 Clock). The “Carry Out” ticks whenever the chip rolls over to zero.

Here is what the setup looks like with the LEDs plugged into their Molex connectors. Have I told you how much I love Molex connectors?

To test the unit, I installed the 555 in the socket along with CD4026 #1. Then I plugged in the LED wires for #1. I figured worst-case I’d burn out just those two chips. I powered it on — and — nothing! No fear, though. I just forgot to plug in the LED ground / cathode wire. Whoops! Once that was plugged in, all was well.

Note that I also had to (temporarily) also tie the Reset and Clock Inhibit to Ground (negative) so that it would “listen” to ticks and not keep resetting.

Once the one digit was done, I followed with the next, and then the third. The third was tricky because I couldn’t get the chip into the socket. After almost ruining one chip, and starting to screw up another, I double-checked the socket. Sure enough, one of the wipers in the socket was acting up. I gave it a little heat with the soldering iron, loosened a bit with a tiny screwdriver, and then it was okay. The little things will get you every time!

At this point, I have a display that cycles though 0 to 999 without a problem. Horray! It even handles the rollover cleanly (goes from 999 back to 000). No Y2K problems.

Next up, I’m going to wire in some temporary switches and see if they will work with the Reset and Clock Inhibit properly. My concern is that mechanical switches are usually pretty electrically “noisy” (they bounce between states when the contacts are close). I’m concerned that the CD4026 chips won’t like this. (Meaning that they will reset when I don’t want them to, or start/stop at will.) Worst case, I’ll wire a debounce circuit into the controller. More parts and work, but it will likely be more reliable. We’ll see.

Update: While trying to get the Reset & Clock Inhibit to work I had an “a-ha!” moment. I kept finding that triggering the Clock Inhibit would often cause the 10’s and 100’s positions to increment strangely. I realized that I really don’t need to mess with chips 2 (10’s) or 3 (100’s) since it’s the first chip that feeds them. So, for the #2 and #3 CD4026 I tied their Clock Inhibit permanently to ground. Only chip #1 is controlled by buttons. More on this in the next post. All chips do continue to have the Reset connected, because they all need to get cycled to zero at the same time.

I spent the afternoon wiring up the LEDs of the shop timer. As we always say, behind every cool lighting effect are a LOT of wires.

The cathodes (negative) of all 42 LEDs are tied together, as the chip I’m using is a “source” (versus “sink”). If you look carefully, you can see that I started on the left — there are a lot more black wires. After that, I decided to streamline and use the leads instead. This made things easier when wiring up the center and right digits.

One the black was soldered, I did all the reds. There is a wire for each LED segment pair — a total of 21 wires (7 per digit). These were then tested and attached to their appropriate Molex connector.

When tying to the CD4026 there are two segments on the left of the chip and five segments on the right. I have 2 and 3 position Molex connectors on hand, so I use a two position on the left and a three + two on the right. To prevent confusion, I put a shrink wrap tag on the left connections (the blue tag) and yellow on the other side.

The wired are inserted in the proper order — they are not random. Check your data sheet for the pinout of the CD4026. Since the connectors are polarized (can only be inserted one way) I can just plug into my controller board and don’t have to label each individual wire. It makes more sense when you work on it.

Next up, building another controller board. Very similar to the Christmas Tree one, so hopefully it will come together faster.