Category: Electronics

All the electronics stuff, microprocessors and more

AMT Boxes of Voltage

Field Guide to AMT’s Boxes of Voltage

We have different types of Boxes of Voltage for your use in the Electronics Area.  While each is a Box that contains Voltage, they are each a special snowflake with special abilities to help you do that thing you want to do.

All Boxes of Voltage have a 1000mA amp meter to show you how much current your project is currently running.  Over one amp and the system will still power your project but the meter itself will show dashes.

All Boxes of Voltage have spring loaded terminals in the front, Red is the positive Voltage and Black if Ground.

USB power port for acyclic Box of Voltage

The Orange Acrylic Box of Voltage is a simple USB powered box of five volts variant.  Plug power into the USB port on the side to feed the box a healthy supply of five volts to electrify whatever it is you need.  The on/off switch is self explanatory.  You can see all the electronics involved in this simple box by looking inside and seeing the electrons flow back and forth within the orange.


Box of Many Volts

The Box of Many Volts is new and improved version of the venerable Box of Five Volts.  Instead of just the five volts, it was decided to add a switch that allows you to choose between that number and the smaller and also popular three point three volts.  Newer electronics projects are moving to lower voltages to save on power requirements and thus, the Box of Many Volts was born.   Notice that the Box of Many Volts is the only battery powered, look Ma No Wires Box of Voltage we have in Electronics and thus needs to have the internal battery charged on a regular basis.  The charging is simple enough, plug it into the USB port on the side and look that the charging indicator light.  Red is charging, Blue is fully charged.  All directions are on the box itself.


The USB PowerUSB powered Variable Box of Voltageed, Variable Box of Voltage is the newest and most complex Box of Voltage available in Electronics.  You will note it has a Knob on it.  This Knob is to turn and twist and adjust the voltage the box puts out, from one point five volts all the way up to over thirty volts.  It’s a multiturn potentiometer and allows you to dial in the voltage you need to great precision.   The Voltage meter at the top of the box will tell you what voltage are currently dialed into and the milliAmps meter is the old Box of Voltage standby.  This box as well requires a USB power connection to turn on to the obvious USB port in the back.   Luckily the Electronics Area has provided twenty USB power ports for the upstairs room for your general use to charge your phone or power a Box of Voltage.


When you are done using a Box of Voltage, please return it to their native location.  While they are wonderful tools, self locomotion is not one of their skill sets.

Project Wrap Up: Purge and Build Day

Our 2016 Summer purge was a great success. We cleaned out a large truckload of stuff and built out several areas. Here are just a few pictures of the upstairs. We have a few projects like building a supply closet to finish up but all in all everyone is pleased with the results.

Everything that had to go
Swanky new laser table
Swanky new laser table
No more piles and you can now easily access the pressure washer and vacuum
Clean and tidy in laser materials storage
Clean and tidy in laser materials
Fully functioning Member Services Desk
New filing and organization of supplies.
New way to organize member paperwork
All the pretty flyers
The new kitchenette complete with microwave and honor bar.
New project display shelves
We organized all the things!
Games and Library.
Looking for something? Look no more… all the forms and paperwork refills ever.
Office supplies all ready to go.
Our clean new after shot.
Taylor Stein of Autodesk showing off Fusion360

A Great Night of Fusion360

Taylor Stein (@taylor_stein) a Fusion360 evangelist from Autodesk came to AMT to discuss Fusion360, how it works and what it can do for hackerspaces.  We had a full house of over 20 people who had questions about Fusion360 and how best to use it for what they are doing.

full house for the Fusion360 class

Fusion360 covers a wide variety of stuff from laser cutting to CNC routing to 3D printing that there was plenty of questions to be had.

Questions from how to export STL files for 3D printing, 2D layout, parametric variable and more where covered.

Taylor showed the way he teaches layout which is to do a quick sketch of the part and don’t worry about lining the parts up.  After the initial layout, go back and use constraints and dimensions to make the shape just the way you want and the relationships between the various parts stay consistent.  This is a different way of layout where the separate primitives like circles, rectangles and lines are defined in relation with each other so as you change one the others move with it.  For 3D modeling it makes things flow far better than having to go back and change everything after one adjustment.

We covered so much material we never really dived into the 3D CNC CAM side of things so another event was scheduled – Monday July 25th Taylor will be back to talk CNC routing and how to do 3D toolpaths and other CNC related questions.

taylor stein of Autodesk showing off the Fusion

Metalshop Vacuum Fixed

The switch went out in the metalshop vacuum and it has been replaced courtesy of the Electronics Area.  Ignore the old switch and look for the new beefy toggle switch with a rubber dustproof cover that will last longer than the old one or so we can hope.  Vacuum now sucks great again. On/off aluminum signage included at no extra charge.


Variable Power Supply fixed

The custom power supply in Electronics has a few basic components.  An old Dell PC power supply, a bunch of wires and connectors and a DC-DC buck/boost converter module to give us variable output.  That module was no longer working so I swapped it out for a new one.   The culprit for the module dying?  No idea.  Could have been a lot of things and it’s going to stay a mystery.

Installing new module and getting the wires backwards.

When installing the new module I had a 50-50 chance of getting the wires right for the direction the knob turned to change the voltage and this time, the odds were against me.  After prying the old module’s hot glued body off the side and desoldering and connecting up the new module it turns out I put the control wires in backwards and you turned it counterclockwise to increase.  Thought about leaving it that way for the comedy factor and decided against that.  A little wire swapping and lo! the knob works as it should.

The new module seems to be working just fine.  I haven’t priced out new DC-DC buck/boost modules in awhile and it turns they are now even lower in cost, under $2 each.  I ordered three as spares just to make sure for next time.

New linear actuators and stepper drivers in Electronics

Added some small linear actuators and StepStick A4988 stepper driver modules to the Electronics area.  These are like the ones you pull out of CD-ROM drives but have an extra 25mm of length to them for a total around 60mm slide length.  Use to make small CNC laser engravers and other like minded projects.  Four wire stepper motors that work well with the standard A4988 modules.  Have your microcontroller of choice move things with 0.01mm accuracy!  In the drawer marked “linear actuators” in Electronics.

HC-SR04 Ultrasonic sensor modules

Ultrasonic HC-SR04 modules now in Electronics

Just added some HC-SR04 ultrasonic distance measuring modules to our stock in the Electronics Area.

This little guy uses ultrasonic sonar to give you a distance reading from one inch to over ten feet.   It’s one of the more common sensor modules out there, tons of existing code and examples and tutorials for whatever controller you are using to talk to it.  Check out the well supported arduino library at or just search for “HC-SR04” and you will see tons of data on it.

In the drawer marked “Sonar”, grab one today to play with it and see how far stuff is.


Mr. Skull

I have been wanting to put *something* in the eyes of a cheap plastic skull for a few years now. As makers we see the potential in everything and every year at Halloween I see these plastic skulls that scream out for hacking. This last Halloween I noticed that Target was selling extra large skulls and thought, hmmm, probably can fit a 32mm square LED matrix in that eye socket. A quick trip over to the office supplies area, grab a ruler, come back and with a few measurements decide to give it a shot.

Captions are nice

This was also for the AMT booth at East Bay Mini Maker Faire to have something interactive that people could play with via their phones. For that I needed a wifi server and for that it was time to try my hand at programming a ESP8266 board. I had picked up a NodeMCU module that is a good breakout for the ESP8266 and started to figure out how to use it. Right about then I found you could program it via the Arudino IDE and someone had posted some example web server code where people enter text and you can process it and do stuff.

Armed with this and a few MAX7219 LED matrix modules I jumped in. There was much flailing about programming wise. As a programmer I’m a good salesman. Finally after getting the code to sorta work I needed to cut open square windows for the LED matrixes. Matrixi?

I was lucky enough to find a tinted piece of 1/4″ acrylic in the scrap bin at AMT that would work. I figured out the spacing of where each matrix should go and laser cut out the holes to hold the LEDs in place. After that it was time for open up Mr. Skull. I cut an opening in the back of his head that would allow me to just put a hand inside. Putting in the acrylic with the LED modules attached, I then took a hot glue gun and without being able to see inside, started to squirt hot glue everywhere inside the head of Mr Skull in the hope that some of the glue would hold the acrylic with the LEDs in place. It just did.

Finding a music stand to put up Mr Skull was a nice surprise. Ever since then he’s been guarding the upstairs and waiting to see what people put in the text box of his website.

I hope to put say a Twitter feed and/or word clock into him at some point. Always upgrades to be done in projects.



In 2015 AMT was hosting a Holiday party and cool things that involved the guests where needed, thus Edgy-Cam was born.

600-feature-gallery-cam2Edgy-Cam is a Raspberry Pi with a camera module and connected to a thermal receipt printer. Using the Canny Edge Detection algorithm, photos are taken with the camera, processed and turned into hand drawnish monochrome image that is printed out on the thermal printer. Like other instant cameras, but with some serious image processing going on. Every processed image is a monochrome 512×384 and given a unique filename and saved on the Raspberry Pi. Images can be retrieved later if people are interested.

600-feature-gallery-cam1The case is made out of 1/4″ baltic birch plywood and was CNC cut at AMT. The black inlay is tolex, a vinyl like material and this is the same pattern as found on Marshall guitar amplifiers. After cutting and assembly, the case had the edges rounded over on the AMT router table. All case assembly, sanding and gluing was done in the AMT woodshop.

The display is a standard 4.3″ composite LCD monitor, mostly used for watching the rear view camera in a car.

The thermal printer is a standard 58mm thermal receipt printer with 5V TTL UART interface. It communicates with the raspberry pi (3.3V) via a serial connection that is run though a level shifter to make the 5V to 3.3V and back play well with each other.

All this is powered by a 8000mAh 11.1V lithium ion battery. The battery has enough juice to run for hours and take and print over a hundred photos.

Fun fact: The Canny Edge Detection Algorithm is named after John F Canny who is a UC Berkeley computer science professor.

The Edgy-Cam software is a python script that is run on bootup, and uses the SimpleCV library to supply the Canny Edge algorithm.