My PCB Fabrication Process

Desulfator

My last desulfator design was Rev B. I decided it should be Rev A (even though Rev B is etched on the board), as it was the first desulfator board I actually built. For future reference I'm doing major revisions A, B, C, but minor (and or pre release) tweaks 001, 002, etc. So this should be Rev A 003, I think.

For more information on the desulfator see my previous post here.

Specs / Limitations

• When I do the layout I've found I can etch down to about 0.010"(50% success), but 0.020" is much more forgiving (80+% success). So I do most of my traces as 0.020". but they won't fit between some pins, so I run a 0.020" trace as close as I can, end it, put a 0.010-0.012 trace in the tight spot, end it, and continue with a 0.020 trace.
• I try to maintain 0.025" clearance around traces, since I don't use a solder mask it helps me avoid bridging traces.
• I flood-fill everything I can, the more copper I leave on the board the quicker it etches.
• So far I only do single-sided boards. Hasn't been a huge issue yet. I'd be tempted to just order 2 sided boards when I need them.

I use the toner transfer method for both the etch resist and the silkscreen. As far as prep it goes like this:

Copper Side First

1. Sand board with 400grit (wet sandpaper) wet with just a drop of dish soap
2. Dry board with a paper towel
3. Apply rubbing alcohol and dry with a paper towel.
4. Print resist on a piece of shiny paper, I have varing results with this, seems to depend on the paper I find. I read that the (glossy) whites of newspaper / magazine ads worked the best, but I find that some heavily colored ads have more of the wax / clay stuff on them and work better for me, with the exception of the silk screen side (more on that later)
5. Align board and paper, either fold the ends over to keep it in place or use a tiny piece of tape. Then run through laminator 5+ times.
6. Soak in cold water until paper starts to dissolve. Some times it peels off, other times I have to rub it until just the toner remains. sometimes I loose traces and stuff, if it's not too tight I continue, otherwise back to step 1.
7. Gently dry and examine carefully, touch up little holes in the flood fills and broken traces with a permanent sharpe(3 coats).

Etching
For etching I use cupric chloride, it works really good above 60F, somewhere around 40-50F and below it's really slow. It needs to work fairly fast, the majority of the problems I've had with it were when it's cold out and instead of 20-40 minutes it took 2-3 hours.

I keep it out in the garage, as I prefer not to risk spilling stuff like that in the house. (I don't want to spill it out there either, but I have better ventilation and access to a garden hose for emergency clean-up)

    8. Etch until traces are isolated.

    9. Rinse thoroughly, then Sand with 400 grit to remove toner, should look
        like this: (note the 2 is missing from the 2013? yep, didn't transfer perfect)

Bottom

Then the Front (silkscreen)
    10. Dry then drill two holes (for through-hole parts) as far apart as possible
          (either corner would be good) and use them to align your silk screen (do
          steps 3-6). I poke a wire right through the board and paper for alignment.
          (remove wire before running through laminator) Note: I try to use mostly
          white paper for this as the colors tend to stick.

Top

When it's all assembled and tested I spray the copper side with several thick coats of Rust-Oleum clear coat.

ATI Hardware Video Decoding on Linux! VDPAU, VA-API, and Flash!

XKCD - Supported Features

I love that XKCD. Anyway, I built a HTPC / home server around a Biostar Deluxe A681-350. It is powered by a AMD E-350 APU that combines a dual core 1.6ghz cpu and an ATI Radeon HD 6310 gpu on one chip. It's a low end system, but I don't need a lot of power here. It handles full screen 1080i video from an ATSC tuner beautifully. It won't play 360p flash smooth at 1/2 screen, and it's a slide show at full screen (1920x1200). It just doesn't have the CPU to decode and scale video. Mythtv uses hardware scaling, so it only has to decode on the cpu, and ffmpeg's software decoders are well optimized.

Today I installed Arch Linux on it. This post was going to cover that, but I discovered hardware acceleration for flash on ATI chipsets works!

Comparison

• With software decoding and rendering flash takes 60-75% of my total cpu time (windowed, scaled as large as smooth playback allows).
• With hardware decoding and (possibly?) rendering it takes 10-25% and plays smoothly full-screen.

 Requirements

• A very up-to date system. (Arch hasn't supported it long, most distro's will probably take some time to, but you may find a ppa or can always compile from source)
• kernel 3.10+
• mesa 9.2+
• libvdpau
• ati-dri
• xf86-video-ati
• flashplugin

Optional

• vdpauinfo (print info about VDPAU (and show's it's working)
• vainfo (same as above, but for VA-API)
• libva-vdpau-driver (allows va-api enabled apps to be accelerated)
• libva

Setup

Assuming you have installed all these packages vdpauinfo should spit out a bunch of information on what's supported. If it doesn't you may need to specify the driver. I didn't need to, but you might (shouldn't) need to add something like this to your environment variables:

VDPAU_DRIVER=

Flash probably won't work until you edit /etc/adobe/mms.cfg and uncomment the line:

EnableLinuxHWVideoDecode=1

I haven't tried it in anything but chromium, so I'll stick to that for now. In chrome://flags I had to enable

Override software rendering list

Now Flash should have hardware decoding! MythTV can be configured to use vdpau decoding and it works nicely too.

VA-API

(I haven't messed with VA-API much, so this may or may not work.) For VA-API it may be necessary to add the following to your environment variables setup. (you don't need this for flash, it only supports vdpau)

LIBVA_DRIVER_NAME=vdpau

One way to do this is create a file (as root) /etc/profile.d/vaapi_vdpau.sh containing:

#!/bin/sh

export LIBVA_DRIVER_NAME=vdpau

Save and add execute permissions (chmod +x vaapi_vdpau.sh . Log off and back on or execute the export command above and vainfo should return the supported codecs.

Notes

1. It only works with the open source driver, though there is a way to get it in fglrx. (see https://bbs.archlinux.org/viewtopic.php?id=166593&p=1)
2. Before "top" shows flash using 120-150% cpu. After "top" shows  20-50% (dual core = 200% max)
3. This works with flashplugin (11.2). I haven't played with it much, but it doesn't seem to work with pepper-flash (11.8). It has lower cpu usage than 11.2 with EnableLinuxHWVideoDecode commented out in /etc/adobe/mms.cfg, but uncommenting it has no effect. Either it's looking somewhere else for that config or it doesn't support it. CPU usage under 11.2 drops way below 11.8 with it enabled.
4. Obviously different chipsets support different codecs, some may not support any at all. The VA-API Wiki page linked below has some info to that end.
5. The Chrome flag may improve overall performance or it may break things / slow things down. you'll have to try it and see.
6. You can check chrome://flash and chrome://gpu before and after to see what changes.

Links:

https://wiki.archlinux.org/index.php/VDPAU

https://wiki.archlinux.org/index.php/VA-API

http://xkcd.com/619/

Arch Linux Fun

I just installed Arch Linux on my laptop, because I apparently have nothing better to do. OK, that's not true, there are lots of things I "Should" be doing, but today I'm messing with Linux instead.

Arch Linux with Cinnamon and an Awesome Wolf Background

Live USB Boot 

I hit a snags right off the bat. I installed the arch iso to a thumbdrive with unetbootin and it seemed unable to locate the media. Just sat there saying "Mounting '/dev/disk/by-label' to '/run/archiso/bootmnt'" and "Waiting 30 seconds for device /dev/disk/bylabel". After a brief search I discovered this was a common problem and the simple solution was to "dd" the image over your thumbdrive. Uh, what about the other files on there? Arch needs to work on this. I know Ubuntu and Parted Magic both fine from a unetbooting usb. So I hunted a bit more and found you can specify the right device as "archisodevice=/dev/sdb1" for example. Ha! too easy, if I specified it as sdb1 it would detect the usb drive as sda. Change it to sda and it's detected as sdb. WTF! Finally I set it to sdb1 and pulled the drive as soon as the kernel had loaded, plugged it back in and it booted right up. Whew, what a PITA just to boot a live USB!

Installation

The installation was complicated compared to Ubuntu or Mint, but I just followed the beginners guide and it went smoothly. Wifi worked and everything. I highly recommend a second computer / tablet / etc. on hand if you decide to install Arch. One reason I wanted Arch was the lack of junk cluttering up my system, things updating in the background, etc.I admit I install a bunch of junk myself, but at least I have some control. It took a couple hours, but I have a usable OS on my laptop. Lots more tweaking to do yet. Seriously, it took longer to get the usb to boot than install the system.

Things I Like

There are a lot of really nice features that appeal to me.

• Boots unbelievably fast.
• I'd eventually like to have a single distro on all my computers. With Arch you can do a headless server, a media center, a desktop workstation or a portable laptop. The base is the same, just install the packages you need for your application.
• A local package cache / repository on my HTPC / Server would be cool. Most distro's can do that, so I don't know that this is a major plus, but it's availible.
• I don't mind the pacman / apt-get / emerge command line tools, but synaptic is slow, and the "linux app store" doesn't appeal to me. So far I love yaourt when used with yaourt-gui, a bash gui for yaourt. It take a little fiddling to get installed, but it will manage pacman, AUR, etc. quickly and beautifully.
• The AUR, it's huge! if you can't get an official package, it's probably in the AUR.
• Arch doesn't hold your hand with tons of helper scripts to make everything "just work". While that can be good or bad, I'm counting it a good, as you get a better understanding of what's going on right from the start. That (hopefully) makes problems easier to solve later.
• It's more up to date. I loved this about Gentoo, that you had recent packages. I installed MyPaint, because it works nicely with my laptop's Wacom penabled screen, and there are all kinds of buttons and options that weren't there on Ubuntu! Ubuntu has 1.0.0-1, Arch has 1.1.0-2.
• Rolling release. In theory once installed I should never need to re-install. just update the system when I feel like it.
• No "Update Manager" nagging me to update all the time. I hate windows for it's constant updates (always at inconvenient times) and some Linux distros seems to want that "functionality" too. It's running in the background without my knowledge too, I don't like that.
• No "error reporting" pop-ups I get too many of these for a supposedly stable system, I understand the need for error reports, but I'm watching a movie and have to get up to get that dumb window out of the way.

Things I Don't Like

• Arch is MUCH more complicated to install as opposed to Mint or Ubuntu. It didn't take me that long to have a working system, but I wouldn't recommend it to a beginner or at least not as an introduction to Linux. I used to use Gentoo, which I feel is even more complicated, but just didn't have the ambition to keep it working.
• The installation ISO really sucked for me, YMMV.
• I have a working system, but it's not nearly as pretty or complete as Mint 15 yet (I installed Cinnamon). I foresee a lot of tweak time to get it just the way I want. This may lead to frustration, like Gentoo years ago. I dropped Gentoo because, at the time, it took a ~3 days of compiling to install the base system and get X running with the basics (Firefox, Fluxbox, file manger, etc.) and the better part of a week for a full desktop environment (KDE at the time).

Conclusion

So far I like what I see. The install was a bit aggravating, but I shouldn’t have to do that too often. I love yaourt-gui, it really makes package management quick and easy.
I think I'm going to swap my HTPC / Server over to Arch eventually. I have some performance issues with Mint 15 and haven't been able to track them down. I don't know if it's Mint or just the my hardware. Either way I hope I can squeeze a little more out of Arch.
If you have an excess of free time try it, it's easier than Gentoo and you end up with a distro that's tailored to you. All the stuff you want with none of the stuff you don't.

Links:

Arch Linux - https://www.archlinux.org/
Yaourt - https://wiki.archlinux.org/index.php/Yaourt
Awesome Wolf Art Source - http://www.deviantart.com/art/wolf-324819837

Briggs and Stratton 21HP Won't Crank Over

My Grandparents new lawnmower refused to start, it would crank part way over and the compression stroke would stop it. It was under warranty, so Sears sent a guy out, it wasn't the valve adjustment, starter, or anything simple, so he came back and put a new engine on it. We've got a broken cub cadet, also my grandparents, that had a Kohler Courage which cracked the engine case after 2-3 years! I told them not to buy another one of those! But the Briggs didn't survive 6 months! The repairman didn't need the old engine, so he didn't mind leaving it for me to try to fix.

Specs

• 21HP Briggs and Stratton
• MFG in 2012
• 331877 - 2371 - G5

Pictures!

Top

Insides

Here's the problem, the compression release weight has failed.

Camshaft and compression release weight

It's made of some sort of cast metal! The hole for the shaft is 1/2 the thickness of the actual weight! What are you thinking Briggs? At least machine it from mild steel, then it wouldn't snap!

Broken compression release weight

Well that's the problem, a new camshaft will cost ~$80, but if it has the same cast weight on it I don't know that I want it! I'm not sure how to proceed at this point. I could try grinding one out of steel, but that's going to be a job.

UPDATE: We decided to go ahead with the new camshaft. It's installed on the Cub Cadet and still working as of April 2015.

Linux Mint 15 and Amazon Video (This also affects other video sites)

I just bought a new drive for my HTPC, A 3tb WD Red, but that's for another post. I had Amazon video working on Mythbuntu (just had to install HAL) but installing HAL on my (fairly) fresh new Linux Mint 15 install didn't work. I finally figured it out, with some help of course

What I've found:

1. Amazon's error is completely useless. It makes you think that you have the wrong version of flash.
2. If you haven't already, you need to install hal and libhal1 "sudo apt-get install hal libhal1"
3. Adobe has a guide for sorting out these problems once you figure out it's DRM related. Here the test page was the most helpful.
4. The test page gave me the cryptic error 3322 - device binding failed. 
5. I tried the solution found here, "rm -r ~.adobe/Flash_Player" it didn't work, but was needed later, after I actually fixed the problem
6. It turns out HAL wasn't starting, I ran "sudo hald --daemon=no --verbose=yes" it spat out a bunch of errors and died. I found the solution here, I'm not sure it's a perfect solution, but I ran "sudo rm -r /etc/hal" then "sudo ln -sn /usr/share/hal /etc/hal" and HAL runs! I think I will copy rather than link it at some point, but that's what I did.
7. I rebooted and the test page still doesn't work, I had to do step 5 again, now it works.

Whew, only took me half the night to figure that one out.

Notes:
I tried this on Linux Mint 14.1 and just installing HAL worked, I couldn't reproduce the problem on 15 by removing the /etc/hal directory. It's possible I corrupted something at some point, I'll try on a clean Mint 15 install sometime and report back.

I also got a 3323 error while HAL was broke, also fixed with #5.


Update: Only steps 2, 5, and 6 are necessary to solve the problem, the others are either diagnostics or irrelevant. (Thanks Douglas Roberts!)

Update 2: This affects other sites (Thanks NikAmi!), I don't really have the time to determine which ones myself, so I'll do a list and update it if anyone finds one that needs it (Post it in the comments). It may help someone else.
Known Sites Also Affected:
NBC Sports

Update 3: There is a package available (at least in Arch Linux's AUR) called HAL-Flash that lets you play DRM Flash content without needing the HAL package / daemon. I'm using it on both my laptop and HTPC and it seems to work fine.

Update 4: Chromium no longer supports NPAPI (netscape plugin API), pepper-flash doesn't work with protected files. Firefox still uses NPAPI and works with Amazon Prime Video. HD doesn't seem to work for me, but SD works fine. I'm not sure why.

RobertShaw HS780 Teardown

I recently replaced a old furnace with a 90+ for my father, I don't recall the make or model of the old furnace, but I salvaged some parts from it to look at. Today we have a Robertshaw HS780 Hot Surface ignition control. The furnace was working, so there wasn't a failure to fix, but it may be of some interest.

RobertShaw HS780

If you watch the video be warned, It's my first attempt at an ad-lib teardown. I kept talking as I figured out the board and was a bit off. It's not bad, hope to do better next time. I think the left small relay is the gas valve, the right one powers up this board when the thermostat closes.

Top

Bottom

By far the most common failure on HSI ignition systems is the ignitor (not this control). They are fairly fragile. Never touch the heating part, it could cause early failure.

Diagnosis would go like this:

• 120VAC present at terminals labeled 120 and NEUT?
• 24VAC present at TH and TR? (thermostat calling for heat?)
• When calling for heat is 120V present at  IGN terminals AND HSI not glowing? (if yes replace HSI, if no suspect large relay)
• HSI Glows and 24VAC present between VALVE and GND? (if yes, suspect gas valve / safety switches/wiring, if no suspect outer small relay)
• Failing all that test the inner small relay, inspect all solder joints for failure and caps for leakage. (if you can't find anything at this point consider replacing the control.)

Sometimes a relay will actually fail (shorted coil, open coil, or bad contacts) and they can often be sourced for $5-10 from digikey or a similar company.

Video Notes:

1. The fan/limit control won't come apart easily.
2. Typical setting are ~100 fan off, ~120 fan on, ~180 high limit.
3. You shouldn't be bouncing off the high limit, if you are you have an airflow problem, oversized furnace, etc.
4. Flame sense is through the ignitor.

Lead Acid Battery Desulfator

UPDATE 2:
My parts have arrived, I've got the schematic sorted out (I think). I think I'm going to do a start to finish post on my current PCB fab procedure and make a new board, even though the other one seems to work. I've got the correct parts and the other pcb is together and working. I'd like to see if they work differently.

Desulfator-RevB - KiCAD 3D Render

The Theory:
When a lead acid battery sets discharged sulfate crystals form on the  plates, reducing the surface area and thus potential capacity of the battery. A desulfator pulses a high voltage / current spike into the battery that causes vibrations that knock the sulfate crystals off the plates.
The usual frequency is around 1khz, though the vibrations are usually in the mhz range. It's described as ringing a bell. The desulfator rings it a thousand times a second and the harmonic vibrations actually do all the work. Therefore the actual frequency doesn't seem to be particularly important.
It would probably be best to remove the battery from the vehicle so we don't pulse high voltage through computers, regulators, etc. It may take a week to several months to restore a battery anyway, so doing it out of vehicle is preferable anyway.

Desulfator Rev. B - Top

The Specs:

• Unit is controlled by the venerable 555 timer, although an attiny would work and allow more control / monitoring of progress.  (Possible future design)
• Should work on many voltages
• May work on nicad's too.
• This is basically a reference design. I want to see if (and how well) it works before spending a lot of time designing my own system (if I even need too, let's not go reinventing the wheel right?)
• I'm trying for a compact design, altoids tin or smaller. preferably 50mm x 50mm, as if it works well I may get a batch made and try to sell them.

Desulfator Rev B - Bottom

Limitations:

• As the battery size increases the amperage needs to increase. Two resistors can be replaced with pots to adjust the frequency and duty cycle of the 555, but this results in increased heat on the inductors. (we'll try the default settings to start)
• Increased amperage requires bigger, more expensive inductors.
• It's not self-powered, so a trickle charge is needed for operation.
• No reverse - polarity protection, hook it up backwards and you will probably destroy it. (I'm going to look into this, doesn't seem it would be too hard to prevent this, definitely looking into this before selling any)

Notes:
I'm basing this on Ron Ingraham's design, I don't think he followed the component numbering of the original, so if they say you can substitute something for R1, it may not be R1 in the schematic.

Update 1:
My parts haven't arrived and I've run out of patience. So I scrounged some inductors (about 600uh and 180uh) substituted some other parts and it seems to work.

Only found two problems:
1. I  missed a trace (somehow missed it in the schematic) and that prevented the duty cycle from dropping below 25% and caused the frequency to change with it. it was really frustrating. I eventually found it and added a bodge wire. Now RV2 adjusts frequency and RV4 adjusts duty cycle. I also added a 180K resistor to RV2, but that's just because I only had 100K pots (should have been at least 300K+. I highly recommend using pots for these. Then you can just dial it right in. (with a power supply and scope or by ear and watching that nothing gets hot)
2. Stupid (me) used non-polarised caps (C) instead of polarised caps (CP) in the schematic, so 3 caps were backwards.

I've corrected all these things in the schematic. I need to clean up the schematic and get it uploaded. I'm not sure if I'm going to roll all this into Rev B or go to Rev C. I have made a number of minor changes, but it's not a redesign by any means.

Rev. B Changes:
1. Replaced R2 & R4 with Pot's for adjustment. Resistors should fit instead, so it's optional
2. Added C41, C43 for more options on the low esr cap.
3. Noted in schematic different options for assembly.
4. Has component locations for several variations on the circuit. Board shouldn't be completely populated.
5. Might have placed the power connector on backwards. Oops.
6. PCB layout is Copyright for now. Free for Personal Use. I may release it to public domain eventually. I just don't want anyone selling these untested boards yet.

Links:
KiCAD + PDF Files

Make sure you add the cache library at the very top of the KiCAD libraries for the schematic. It's a PITA it doesn't do this automatically. The PDF's may or may not work, they gave me a fit. Make sure you print at 100%, no scaling.
Pictures of latest board in my PCB Fab post

Desulfator Information (mine is based on the low power - Ron Ingraham design)