DIY Digital Clock: Take 2!

What time is it?

Time to make a new clock!

About a year ago, I designed and assembled my own custom made clock. You couldn’t say it was in an enclosure since its guts were spilled out on both sides of a piece of foam core. I felt like, a year later, it was time to redo it and put it into a proper enclosure.

So, what time is it? Time to build us a new clock!

The Guts

1

I tend to get carried away and too focused to take proper progress pictures. This is literally the first picture I have from the electronics part.

Soldering all of those LEDs and components took a full day. I used hot glue to try to keep multiple wires in place to solder as fast as I could but it didn’t do the best job to hold them in. At time, the glue would fall away from the PCB. Still, it’s better than fiddling with one wire at a time.

The only difference from the prototype build is a lower resistor value for the LED resistors.

Putting Together a Box

2

Foam core is a favorite in my “lab”. It’s all I use these days because all it takes is a knife to cut and it’s inexpensive and accessible (Dollarama rocks). I built a simple black box with a white cover place. I was hoping with a lower resistor value on the LEDs, they’d be able to shine through the white foam core.

3

With the soldered parts and the enclosure ready, it was time to put it all together.

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I glued a piece of foam core behind the control board to isolate the connections on the back with the display connections. I ended up mounting the two display panels on it’s own piece of foam core anyway so I guess that wasn’t really necessary. The display foam core backing fits tight with no need for pin or glues to hold it in place.

5

The white foam core was still too think for the LEDs so I ended up going back to a plain white sheet of paper. It’s not noticeably brighter than the original prototype with the paper.  The piece of paper is held up by two strips of foam core on either side.

I didn’t like the look of it at this point but it was the end of the weekend so I left it for now.

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I still like how sleek the black foam core looks, even with a few imperfections here and there from a not-so-sharp knife.

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After a few days to think about it, I realized simply turning around my diffusing screen pulled the look together.

8

Time to pull the plug on the prototype and enjoy something new.

Thanks for reading!

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74HC595 Shift Register Board Revision B Preview

I said when the year began that I wanted to get back into Eagle and revisit some of my PCB designs, as well as start some new ones. My first project for the year in Eagle is giving some attention to my 74HC595 Shift Register Board. The original version, even with its flaws, was used in the latest Light Show to help control 10 RGB LEDs. It worked out quite well but, again, it had its flaws. I’d love to have a revised board in my hand by the time I’m ready to go back to the Light Show.

sch1

This is the new schematic for the board. It includes a breakout of the Output Enable pin which gives you some PWM control. Using this pin will PWM all outputs over the two shift registers (16 outputs), so my idea is to chain three together so I can dedicate each board to a color (red, green, blue). Of course, it’s not as flexible as something like the TLC5940 which has 16 channels you can PWM individually, but it’s cheaper…

Anyways, if the application doesn’t need PWM, I added another ground pin next to the OE pin so you can just connect them together. When you do that, the outputs have no PWM control. The first version of the board had the OE pin already connected to ground in the schematic.

brd

Admittedly, my first PCBs were auto-routed as I was just getting acquainted with Eagle. I’m still learning but I managed to route this one manually. There seems to be a lot of technicalities on what you should and should not do when laying out a board but I don’t think my design is too much off what the auto router would have done. I tried the auto-router earlier and it did some really odd looking turns and loops around pads… Anyways, it’s just like solving a puzzle, though it takes me a few tries to get it right.

If you’re interested in buying these boards, let me know. I’m trying to decide on how many to get made.

Thanks for reading!

Attiny85 Programmer/Breakout RevB2 Preview

A little while ago, I posted about some updates to my Attiny85 Programmer & Breakout PCB that showed off a new design with a breakaway Programming section of the board. I threw that out and started over again. There’s still some work to be done but I wanted to show where I’m going with this.

render_frontThis is a render of what the board looks like. The program I use to render places the design on a rectangle so keep in mind that the purple outline would be the edges of the board.

The Power In and Attiny85 have swapped places. I’m going with an SMT LED and resistor for the power indicator to open up some more room on the board (labels are in the design, won’t be printed on the board).

The board is designed so that the Program section would be broken off once you’re ready to use the the board as a breakout. What if you realize later on that there’s something wrong in your code? You could connect up your Uno using the Breakout section, but you’d still need another capacitor for the reset pin on the Uno, and this kind of defeats the purpose of the board. I’m working on an experimental idea to make it easier. The pads next to the Power In area is a temporary programming area where you’d connect the Program section. The problem is making the connections. You can’t really connect the Program section back directly using headers because then you have no way of making another set of connections to the Uno. The best way would be to make the connections on a breadboard. It’s not ideal, but it’s still easier than looking up which pins of the Attiny85 go where on the Uno.

render_backI’ll put a URL to an updated manual on the board again. I still want to get some instructions on the board with the space I have but the small size of the board makes it difficult to put anything really specific. I’m on the fence on whether the text on the Program side will stay (the lines it’s referring to are on the top side of the board, I need to add lines on the bottom side too).

I’ve been making an effort to getting the sizing of text (and traces) right since I made the text on my AMS1117 board a bit too small.  I use mm to design my board, but a lot of help resources and parts of Eagle use mils. I made a table of conversions between mils and mm. I put it up for download as a Word document and pdf in case you’re interested. I got the table from here but formatted it to print.schematicI redid the schematic, chopping it up into sections and adding labels. Everything was directly connected to each other in the first schematic. It was messy, but not having things directly connected to each other does worry me in case something isn’t connected properly. I’m constantly checking connections and working on the other details of the board I talked about above so I’m taking my time. There were people watching the Attiny85 Programmer and Breakout Rev A board on eBay so hopefully that means there is some legitimate interest in these boards. I would like to get them manufactured.

Just a note for people who are Googling around for the warning, “Segment of net [name] has no visual connection”, I deleted the label of that net and placed a new one to clear the error. I couldn’t find much help when I was searching around so hopefully people land here if they run into the same warning.

Anyways, thanks for reading!

New PCBs! (AMS1117 regulators & ATmega328p breakout)

I’m excited to finally have my second round of PCBs here! The designs are an AMS1117 regulator board and an ATmega328p breakout. I already have notes to share from soldering one of each to start testing them. The notes in this post are just from assembling them. I will have a separate post that goes into detail about my tests with them.IMG_20140918_193548This is how the boards were designed. They are meant to split apart easily with the tab between them. I got a little excited and went for it without scoring it first, so I destroyed one ATmega328 breakout since the weakest points in that area are the pin pads 2-4. No worries though, I got a few extras in this batch of PCBs, probably because they don’t take up the complete 5x5cm area I have to work with. I tried splitting another board by scoring both sides with a knife and they split cleanly without damage to either design.IMG_20140918_193021This is the AMS1117 board that has two fixed voltage AMS1117 voltage regulators. One produces 5v, the other produces 3.3v. It is a tight squeeze because the capacitor footprint is smaller than the actual capacitors, but it doesn’t seem like it’s an issue. On the back side is a note, written in text that’s a bit too small, that the dropout is 1.3v so you have to supply it with at least 4.6v for 3.3v or at least 6.3v for 5v. I forgot to include the drop of the diode which should be 0.7v, but most applications would probably use a 9v battery as the input to this board. It will be part of the testing, though 1.3v is the maximum dropout so results may vary between the regulators. We’ll see how the tests go.

It was fun placing the SMDs and trying to align them properly. It bugs me when my components end up in some awkward position so I feel the pressure with these small SMDs. I got to solder SMDs back in school where we used a flux pen, solder paste, and a toaster oven. I have none of those things so it’s hand soldering for me.
IMG_20140918_192836This is the ATmega328p breakout board. (The crooked oscillator is bugging me.) I really bumped my head with that terminal block for the power input. The terminal block I used on the board is 3.5mm while I’m sitting here with 5mm (0.2″) terminal blocks, which are the ones found on my Attiny85 board. It’s not a big deal as I can always go and buy them, or I can just solder wires like I did with this one.

The boards have proven to be functional, together no less. Again, full test results will be coming up shortly. Stay tuned! Thanks for reading!

Back to PCBs

With the first fountain show complete, I’m taking some time to consider my next plans for it. I have a few ideas but I don’t have the motivation yet to go through with any of them. I feel like switching gears back to my PCB designs because I had projects going on that had stopped because of the fountain project.
2This is the next board that I’m working on sending out to get manufactured. The main design is the ASM1117 voltage regulator board because I’d like to try working with SMT parts again. I already bought the ASM1117 regulators so I kind of have to get this board made eventually. I’m just a little worried that they won’t work like the shift register boards. I’m still trying to figure that out…

The other design is an Atmega328p breakout. Pretty straight forward.

I hope to send this board out by the end of the week to get made.