Tag Archives: lab

New Flickr Group for your Electronics Workbench

workbench

Ahh, the electronics workbench – shrine to the electron, the diode, the transistor, the soldering pencil and flux pen.

You can learn a lot about someone by looking at their workspace. Note the way that they store components (in pullout drawers or plastic organizers?), hang test leads (on hooks or wire racks, or on a nail?), and keep spools of wire at the ready for repairs and new projects.

A look at someone’s electronics workbench gives you a small glimpse into what is usually a fairly personal space – a space where visions become reality and electronics projects are brought to life.

While there are quite a few electronics workbenches on flickr, I determined after a quick search that there had been no attempt to bring all of these glimpses into a hobbyist or engineer’s soul together into one place.

And thus was born the Electronics Workbench flickr group:

Electronics Workbench

Getting organized in the lab.

Me in my electronics room.  I'm holding the beginnings of a cryogenic receiver project.

Have a photo of your bench? Add it to the group!

No? Then go downstairs into your basement, out into your garage, or up into the attic and take one!

And don’t spend too much time cleaning it up first – noone will believe you that your workbench is that clean when we’re not looking.

Also, a shoutout: This group was inspired in part by the Workbench of the Week (WOTW) page over at The Amp Hour. I don’t think WOTW has been a feature on the show for several months. Maybe we can get Chris and Dave to bring it back??

Happy soldering!

– Jeff

www.flickr.com

items in Electronics Workbench More in Electronics Workbench pool

Test Jig for the HV Rescue Shield

HV Rescue Shield Test Jig

This weekend I threw together a simple test jig for the HV Rescue Shield.

The completed jig is shown above.  There are four header pins, one at each corner, that are used to align the  BUT, or board under test.  The Kapton tape insulates the two bottom standoffs from shorting against the bottom of the BUT.

Pogo pins are used to make electrical connection to the BUT.  I connect to +5V, ground, 12V_EN, and 12V_SW (the +12V output).

These pogo pins are similar to the ones Ladyada uses in her test jig tutorial.  You can get these in a wide variety of styles on eBay. I think the ones I used are P75-K “chisel” type tips.  They just happen to fit into the existing holes in the PCB with no modification.

The height can be adjusted by melting the solder around the pogo pin and pushing it up and down.  I lost a couple pins when I pushed them down too far and let solder get into the spring mechanism.  Oops.

HV Rescue Shield Test Jig

The standoffs are made of reclaimed screws that I had lying around.  Right now I am connecting to the pogo pins with clip leads, but I might make a more permanent test setup someday.

HV Rescue Shield Test Jig

To test a board, I align it with the header pins and push down.  Easy.

Previously I was using something similar, but without alignment pins or standoffs, so it was challenging to align and push down the board-under-test with the pogo pins without the whole setup sliding around the bench.  The new jig works well and makes testing a large batch of boards a breeze.

BUT

Here’s my current testing setup.

Testing the HV Rescue Shield

The output of the 5 to 12V DC-DC converter is shown on the top display (that’s my beloved Fluke 45 bench meter) while the power supply current is shown on the bottom.  The toggle switch on the bench just to the right of the jig is so I can toggle the 12V_EN line and make sure the DC-DC converter turns off too.

This board looks good, and so did 29 of his friends.  0% failure rate on this build!  I seem to have my process pretty much figured out now.

Tested boards

AO StereoStar Microscope Wiki Page

Today, while I was tweaking the microscope that I use for surface mount soldering, I realized that I have collected quite a bit of hard to find information about this circa~1975 model 569 American Optical StereoStar Stereoscopic Zoom Microscope (say that three times fast!).

So, I made a wiki page and put it all online.  StereoStar owners, rejoice!

AO StereoStar Stereo Zoom Microscope Resources

Improvements to my microscope setup for SMT work

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.

Stereo Zoom Microscope

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.

Supplementary Objective

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

Secondary objective installed

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:

Fluorescent ring light

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:

New microscope illuminator setup

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.