MightyOhm

Last May, my brother and I went on a week-long roadtrip across the US.  Ambling down the highway in a very large moving truck, we travelled from California to Texas by way of  Tuscon, Socorro, Albuquerque, Santa Fe, Los Alamos, and quite a few rest stops, gas stations, and fast food restaurants in between.

Intoxicated by the chile verde, we spent considerable time in New Mexico, a state that neither of us had visited before.  One of the highlights of our visit to the Land of Enchantment was a side trip to Los Alamos, birthplace of the atomic bomb and home of two major attractions for any electronics geek:

Los Alamos National Labs

Sadly, armed guards prevented us from taking a close look at the Los Alamos National Labs.  Actually, the museum is pretty decent, and includes scale models of Fat Man and Little Boy, some exhibits about radioactivity and nuclear weapons, and a short film about the history of the labs.

The Black Hole

The Los Alamos Sales Company, aka The Black Hole, is a surplus store started in 1951 by the late ‘Atomic’ Ed Grothus, a former LANL machinist turned peace activist.

I have never seen a more fascinating collection of electronic test equipment, laboratory glassware, chunks of machined aluminum, LN2 dewars, bell jars, dusty old databooks, and just plain weird stuff.   Good news: most of it is for sale, although there are very few price tags around and some items are probably in the “if you have to ask…” category.

A controversial Los Alamos institution, it has even been the subject of a documentary, although I haven’t managed to track down a copy (yet).

Here are some photos to give you a taste of what it’s like to wander around The Black Hole:

A geiger counter near the front door clicks away in response to some radioactive source nearby.

One of several aisles of surplus test equipment. You name it, it’s here.

Mmm…  Organic Plutonium!

Anadex CF-300R Timer with gorgeous nixie display.

Racks of vintage test equipment.  Scopes, counters, power supplies, etc.

Period datasheet for the Fairchild uA741 operational amplifier.

Pan Am hard hat.

Oscilloscope with permanently attached scope camera.  This is the same setup you see in the pictures of atomic bomb test shacks in books such as How To Photograph an Atomic Bomb, by Peter Kuran.

Honestly, the pictures capture only 1% of what you’ll find here – you have to actually visit to appreciate this place. Oh, and budget an hour or two minimum.  If you enjoy looking at dual trace oscilloscopes and dusty cold war relics as much as I do, you’ll need an afternoon to really do it justice.  If you want to see more, check out my Bradbury Science Museum and The Black Hole albums on Flickr.

By the way, The Black Hole is listed on the Surplus Electronics page of the MightyOhm Wiki.  Is there a surplus electronics store in your city?  Add it to the wiki!

I am pleased to announce that the MightyOhm Wiki is now online and open to the public.

While there isn’t a ton of content yet, my hope is that the wiki will become a useful means to share information and resources relevant to the site.  At the moment, there are pages for electronics vendors, hardware/software tools, and PCB manufacturers.

Another page I have been working on for a while is the surplus directory, which lists surplus electronics stores around the country.  If you have a favorite surplus goldmine in your area, please create an account and add it to the wiki!

MightyOhm Has a Wiki.  Check it out.

This weekend I hosted a post-Halloween kit building party at MightyOhm HQ.

Nine close friends built Conway’s Game of Life kits from Adafruit Industries.  This is my favorite kit for these kinds of workshops because it’s easy for beginners to complete in about 2 hours, and when everyone is done, you can wire all of the kits together to create one large cellular automata display.  The last time I helped people build this kit was at a Make:SF workshop at the TechShop in Menlo Park.

Here’s a timelapse video of the afternoon, shot with a Logitech QuickCam Vision Pro webcam on an Eee PC 4G running Booru Webcam 2.0.

The capture interval was 5 seconds.  I used Quicktime Pro to stitch the images together at 15fps and iMovie to add titles and music (Turbo Outrun by FRP from remix.kwed.org.)

I wore my Halloween costume for most of the afternoon.  What am I?  Most people on the streets of San Francisco had no idea…

Safety first!

Stuart was the first to finish his kit:

Soldering the kits together to form the matrix:

Nine happy kit-builders with the 3×3 matrix they created with their finished kits:

And lastly, a video of the 3×3 matrix in action:

Three people had little to no soldering experience at the beginning of the afternoon.  Everyone who came went home with a working kit.  Success!

Why do I need a microscope for SMT?

The single biggest challenge to doing “real” SMT work (0805 or smaller components and fine lead pitch ICs) at home is being able to actually see what you are doing.  I know that there are many hobbyists (and maybe even some budget-conscious professionals) who will disagree with me, but I wouldn’t dream of working with surface mount components without using a microscope.  I’ve tried many alternatives, including a 10X handheld triplet loupe, a magnifier ring light, even a nausea-inducing magnifying visor, and none of these even come close.

In case I haven’t made myself clear: I would rather solder SMT’s with a 150W soldering gun than with anything other than a decent stereo microscope.

In January of this year, I scored a stereo zoom microscope on eBay.  While my scope is far from state of the art (it’s a “vintage” American Optical model 569) the optics are fantastic and it quickly became the most prized piece of equipment in my shop.  Here’s a photo of the scope shortly after I added it to my lab, for more photos and information about it, see my original post.

For the first few months, I used the scope pretty much as it arrived.  One of the first major tasks I used it for was assembling the first batch of AVR HV Rescue Shields, and for this purpose it worked extremely well.  However, as time went on, it became clear that I needed to improve my setup in a couple areas:

1. The magnification range of 7-30X was great for working on a few tightly grouped 0805 or smaller components, but was too high for general PCB work.  A typical BGA package was larger than the field of view.
2. The included incandescent projector-style illuminator (shown piggybacked on the scope in the photo above) could only be placed in a limited set of positions and did not have adjustable focus – it made a nice, bright spot in the center of the image that didn’t fully illuminate the field at low zoom levels.  While it is removable from the scope (this provides a workaround for these issues), the included stand took up too much bench space to be practical.

Upgrading the microscope:

The first upgrade I made was to add a secondary objective aka barlow lens to the scope.  A secondary objective serves to increase or decrease the total magnification of a microscope, while simultaneously trading off working distance, the distance between the bottom of the microscope and an object in focus on the bench.  In my case, I added a 0.5x secondary objective, which gave me half the magnification while increasing my working distance by approximately 2x.  While American Optical stopped making accessories for the StereoStar 569 long ago, Reichert, who acquired AO’s microscope line, still sells parts and accesories, including the #575 0.5X secondary objective, shown below.

The secondary objective screws into the existing threads on the bottom of the microscope.  Here it is installed on my scope:

Now with the secondary objective installed, I have a zoom range of 3.5-15X and a working distance of 6-8″.  If I need higher magnification, I can always remove the lens.  Perfect!

The second upgrade I made was to add a fluorescent ring light to the scope.  I picked up the cheapest one I could find on eBay.  This model is sold by Amscope, outputs 8W, and is available for under $30:

The ring light conveniently attaches to the newly installed secondary objective by tightening three thumbscrews, and provides a decent amount of light that fully illuminates both the object I’m working on as well as the surrounding workbench area, which has been surprisingly helpful.   Best of all, the new light stays out of the way and provides more even illumination than the halogen projector that came with the scope.

Here’s a photo of the microscope setup as it looks today:

Conclusion:

While the changes I made are significant improvements over my original setup, I have made a few observations that may lead to even more tweaks and upgrades in the future:

• The increase in working distance due to the 0.5x secondary objective is great, but it puts the scope significantly higher above the bench.  I didn’t appreciate that this could be an issue until I had to buy a taller lab chair to see through the eyepieces!  I’m not sure how to work around this, but it’s good to be aware that more working distance isn’t always a good thing.
• The color temperature of the fluorescent ring light is very poor (cool) compared to the halogen illuminator it replaced.  This gives everything a slightly depressing blue cast and is far from a true color representation.  Most noticeable are tantalum caps, which go from bright orange in color to a sort of slightly orange-ish dark grey under the scope.  Yuck!
• Ring lights can create pretty nasty glare.  This might be a side effect of how I have the ring light mounted or the distance to the bench.
• The 8W fluorescent lamp is ok, but more light would be better.  Fluorescent ring lights are nice and cheap, but better performance can be achieved with a significantly more expensive fiber optic illuminator.  I may look into getting one of these in the future.

Despite these minor issues, I am pretty happy overall with the new setup even after a couple hundred hours of heavy use.

I just got an e-mail from HSC Electronic Supply announcing their 45th Anniversary Sale (aka Sidewalk Sale), which takes place this Saturday, Sept. 26th.  If you are in Silicon Valley this weekend, this is definitely worth checking out.  If you want to get an idea of what this event is like, check out my photos from last year’s “Warehouse Clearance Sale.”  (It seems like they change the name of this event every year now!)

45th Anniversary Celebration
Local Customer? Come on in and celebrate with us and save
10%-60% on everything in our stores. One day only!
Out of the Area? For our online customers, from September
23rd to 27th, HSC will offer *FREE shipping plus an additional 10%
off any order over $50.00. Just mention “Anniversary Special” in
the shopping cart order notes and we’ll take care of your discount.
The 6,000 items listed online are just a sample of our extensive store inventory.
Don’t see what you need? Please don’t hesitate to call us at 1-800-442-5833.

HSC is having some online specials too, although if you shop online you are missing out on 90% of the fun, such as sifting through crates of miscellaneous electronics parts!

Every project I work on usually involves at least one trip down to the South Bay to visit HSC, and I usually find at least a few interesting odds and ends at their annual clearance sales.  And while you’re in the area, I highly recommend a side trip to Weird Stuff Warehouse in Sunnyvale as well.