A Workspace for Playing with Analog Circuitry

Paulo Peres, an enthusiastic electrical engineer interested in analog hardware and MCU projects, has a well-stocked workspace located in São José dos Campos, Brazil. His space has all the necessary tools and parts needed for him to take on new electronics projects. It's clear that Paulo has a passion for analog circuitry, which he recently described to us!
 
How would you best describe your space? And how do you use it?  
Where is your space located?

Paulo: There is a kind of external bedroom/home office in my backyard. It's not so small, but it's cluttered with equipment, tools, and parts.


 
How long have you had your space?

Paulo: In the present version, less than four years; but I have been maintaining this space to work for the last 30 years. I've been using the pictured workbench since the beginning of the '90s. What were your original requirements and goals for the workspace?

Paulo: Well, in fact, I was concerned about properly accommodating my equipment collection. I had bigger spaces in the past. So, I have a little more equipment than I can use at the same time. Some are bulky and some are not fully functional. (I'll fix them eventually.)

When I moved to my current home, this space was the best value for money. I can operate most of my equipment with some comfort. However, some extra space for the computer would be nice. I used a lot of space just to accommodate steel shelves.
 
Tell us about your technical interests. What sort of things do you like to work on in your space? Why do you focus on such projects?

Paulo: I like to play with analog circuitry. Although I also work with MCUs/CPUs, I have interest in SMPS, power electronics, signal generation and shaping, reverse engineering and test equipment restoration.

I like to develop analog "front-end" circuitry to interface with MCUs. Using capacitance measuring to determine humidity in materials or differential magnetic sensors to directionally detecting metals, for instance. To give an idea, I already did reverse engineering of voltage multipliers to make new ones for Tek scopes. 

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What tools do you have in your workspace? How and where you store your equipment?

Paulo: I have a lot of things. There are five operating oscilloscopes, one restoring, and a "fractional" number of oscilloscopes waiting for a good idea. At least five different multimeters, two AC voltmeters, four frequency counters, three power supplies, three function generators, one pulse generator, one current probe, three LCR bridges, one soldering station, two rework stations, among many other items. The most used equipment sits directly on the steel shelf above the workbench, the rest distributed on steel shelves behind my chair. In addition, there's an inventory of electronic components in plastic drawers. All listed in the EleLa database.
 
What do you consider to be your most important piece of equipment?

Paulo: It's hard to say. I have great pieces of the history of technology in my lab. But to pick just one, it's my Tek 7613 scope. It's equipped with two 7A26 plugins plus a 7B92, it has analog storage and analog readouts. It works so well that I rarely turn on my HP Digital Oscilloscope (which is 20 years younger). The best word I have to describe the four simultaneous green analog traces on the screen is "magic." My Philips PM6303 RLC bridge that I brought “back from the dead” is in second place.
  What is special or unique about your space?

Paulo: The space is actually common. What makes my place unique is the collection. I like oscilloscopes because they are the synthesis of signal visualization. When talking about analog, it expresses the state of the art of CRT control techniques. RLC bridges bring the pinnacle of electrical properties' measurement methods. And the remaining, gives me the means to replicate or isolate some particular phenomenon to study and build something.


 
Do you have any plans for your space? Perhaps some new equipment, tools, or storage? 

Paulo: I'm always looking for "new" old instruments. Recently, I bought a used stereo microscope to help with SMD soldering, but it needs a touch up before I can start to use it. A 3D printer is an idea for the future.
 
Do you have a favorite electronics-related project? What did you build? Why did you build it? What was involved? 

Paulo: Was a concept proof for a dialysis machine, years ago. However, the idea was not mine. I just helped to make it viable. It consisted of an oscillating steel blade inside a fluid “channel.” I built 12-channel current amplifiers to control the magnetic field needed to move the blade (generated by 12 solenoids), a five-channel differential capacitance meter for sensing its position and a 4 to 12 analog demux with level hold because the available hardware (in the controller) had only four analog output channels. I used TL074, 4016, LM675, etc. There were a lot of simple problems to solve, but was really cool to solve it. Nevertheless, the prototype worked with minor issues and was considered a success.
 
Do you have a dream project? 
 
Paulo: Recently, I decided to build my own RPN calculator (a kind of HP LED display era revival; and I’m doing it presently). It makes me think about how far I can go if I start to design a high-end analog scope. I have plenty of ideas with scopes, I like sensors and measurements and would love to develop a graphic impedance analyzer. Would be perfect if it could be analog. To put two traces on a CRT screen, R+jx. Operable like an analog scope. I know a microprocessor solution would be easier, but where is the fun?
 
Do you have any advice or words of encouragement for other Elektor community members who are thinking of putting together a workspace?

Paulo: Read the classics! And with “the classics” I mean the Tek and HP service manuals from the 1970s. There is more to learn there than you can ever imagine.

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