I’m finally getting back into designing boards. I just ordered some test boards from OSHPark. Love that site and there low minimums and affordable pricing.
I have been working with Wemos D1 Mini units and need to build a carrier board that supplies power and holds other components. I drew up the pin outline in Eagle and sent it off to make sure it’s right. I find this saves alot of aggravation when drawing my own parts.
Now that I’m designing PCB’s I figured I should look at an upgrade of Eagle. Ruh Roh! Autocad bought them. Autocad makes nice stuff, but the baby from the marriage of CadSoft and Autocad is likely to need time to grow up. They seem to have stopped selling Eagle and are talking about something new. Branding and messaging is a mess and there is annoying pop-up all over Cadsoft’s site. Messy Marketing makes it look like a Walking Dead website. 🙁
Well, that’s as good of an excuse as any to survey the field and see what’s out there. Altium seems okay, but I’m not ready to throw $1k at it and I don’t want a product filled with gotchas and fish-hooks trying to upsell me. I already have Quick(sand)books for that.
Enter KiCad. It’s open source, GitHub friendly, and has a huge number of users. It’s also multi-platform. The price is right, just bits from Comcast which are $120 for 1 TB/mo. 300MB later, I run the installer. There are some features to be desired, like auto-update. It has it’s own set of vexing issues, but the documentation and YouTube videos are really good. There are a number of things that are fundamentally easier to do… such as part design/layout. Other things are awkward at best, such as the inability to set defaults or work with Design Rule files for various fabrication houses. One particular nice thing is that Eagle was always picky about design scale i.e. units/millimeters and was notorious for leaving wires disconnected. KiCad seems to have a more intelligent UI that avoids this issue while being far easier to share design files etc.
Like all PCB design tools, learning curve is a modest description…. I prefer to call it a learning cliff.
So… I learned a bit about RCA and VGA today. VGA is a component input, RCA is a composite input. What does this mean? RCA has the signal all on one wire and the devices that use it separate it electronically. This compromises fidelity, or information density which is why it’s great for 640×480 and TV but not for 1080p or 4K. VGA on the other hand is a component signal, red/green/blue, vertical/horizontal sync etc.
Here is a great image of VGA, courtesy of Instructables: (click to view the article)
I’m not sure how well this would work… it’s a little too good to be true.. but it gives you an idea of what is going on.
Here is a better illustration of the VGA pinout: (courtesy of stackexchange, click to view source article)
Here is a schematic that backs up my hunch that the instructables is too simple. Courtesy of Next.GR (click to visit)
This circuit only generates greyscale…. or black and white video.
In case you were wondering how hard can a video signal be? lol…. it’s complex. Really a marvel of radio engineering. Courtesy of Field Effect LLC, click to follow to article.
I have other objectives than engineering this solution…. and I only need one…. so I bought this on Amazon. (click the image to go to the product)
I ran into an issue where I had many sleeping database connections that were chewing up server capacity. It came down to a file called XMLRPC.php which is used for inter-site wordpress communication. Blocking it disables the sleep commands it was generating. 🙂
adding this to the .htaccess file dealt with it.
deny from all
That also breaks some trackbacks, etc…. but I can live with that.
I ordered some 1 Watt and 3 Watt LED’s from AliExpress. They were cheap, like 10 cents each. Free shipping. All good till they showed up mixed in an envelope. In regular light they are identical in appearance. Fortunately I had a small UV flashlight I had ordered. I thought it was interesting and had ordered it for $5.
It turns out that the LED’s are vastly different in appearance under UV light. This enabled me to quickly sort them. You can see the 3 Watt LED’s on the left and the 1 Watt on the right. I know the size based on the quantity I ordered.
I licensed Eagle 6.5 in 2013. When I resumed designing boards this year it started bugging me to upgrade. Figuring it would be disruptive I put it off. Well, I went to finally upgrade this week and discovered that the ‘light’ license has no upgrade option. It’s another $69 if they want me to upgrade. Hmm, what do I get? So I read the release notes and couldn’t find any useful improvements. They certainly don’t seem to have fixed the things that irritate me the most about the program, such as:
Annoying habit of not connecting parts to wires if the scale is off just slightly.
No way to “fix” such connections.
Parts get out of alignment and can’t be “snapped” to alignment.
no decent basic parts libraries for stock discrete components. Forcing one to scrounge for SparkFun and ADAfruit libraries, or make your own.
Not being able to “pin” the ground planes to the outline of the board.
Having to “smash” parts and manually move the labels
As a bonus, the upgrade is one way for your files. So if you open something in v 7.5 you “convert” the file and can’t go back to it with an older version.
I decided to stay put on v 6.5. It works just fine and I haven’t found anything I need in the new version.
I had some time this evening to assemble a prototype for the power supply. It immediately drew 1amp and started to blow up a capacitor. Not good. I’m not completely sure what was wrong. The only deviation had been using a 1N5818 diode instead of a 1N5822 on the feedback circuit. I don’t think this is critical and it looks like it’s used to bleed down voltage when the circuit is off.
There were a number of minor things wrong, so I incorporated some changes and made v1.2 The input/output headers weren’t labeled and were too close together for screw terminals. The diode pads were drilled too small and too close together, i.e. I used the wrong package size. I also didn’t like the input and output side by side. I also changed the package layout for the IC. I’m not going to bend the thing over on it’s side. That’s silly for this application.
I ordered new boards from OSHPark tonight. Should have them in a couple of weeks.