Tenma Portable Hand Held Supply – Workbench Wednesdays

element14 Presents on YouTube

The TENMA portable power supply (72-2660) offers bench supply capability in a backpack friendly package. The single output is capable of 45 watts with up to 30 volts and 3.75 amps out. The built-in USB ports offer an easy way to power 5 Volts Arduino or Raspberry Pi projects while limiting their current. See how this portable supply performs, the things the Bald Engineer likes about it, and the points to consider before buying

This $100 power supply is cool. It’s about the size of a digital multimeter but can output 45 Watts. Both voltage and current are adjustable. It can output up to 30 volts and 3.75 amps, but not at the same time. It does have a flaw in its design though. Fortunately, I was able to find and apply a fix for it. Overall, if you want a portable adjustable supply, this one is worth checking out.

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Classic, vintage, or retro computer systems are well documented on sites like Wikipedia. Their historic position is well known. Their schematics are even published from original documentation. But how useful are those schematics in their current form? (Spoiler, not much.) Presented at KiCon 2019.

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high-end-oscilloscopes-evaluation engineering

The concept of high end varies depending on what you are talking about and who you talk too. In this Evaluation Engineering Evaluation Engineering article the author discusses high-end oscilloscopes. I am mentioned several times in this article as part of my day job at Rhode and Schwarz. There I am a product manager for oscilloscopes in North America. We have scopes that range from 50 MHz to 8 GHz.

For a little bit of context let me explain how this type of article works. The author, or editor, reaches out to some field experts. Each person is asked to fill out a written interview form. From there the author compiles the responses into a story like this one. This process is always nerve racking to me. I always worry I’ll misquote a specification or make a major typo. I don’t get see the article until it is published.

If you aren’t familiar with high bandwidth oscilloscopes, I think you will still find some value in reading about my favorite test tools.

Read the full article

Date: March 25, 2019
Appearance: High-end Oscilloscope report on Evaluation Engineering
Outlet: Evaluation Engineering
Format: Magazine

Surface Mount Rework Tools – Workbench Wednesdays

element14 Presents on YouTube

In this element14 Workbench Wednesdays episode, I review tools provided by Weller which are suitable for surface mount soldering. Through-out the soldering series, I have been using mini-projects to see how the gear works. Making this particular video was special to me. The subject was a TI-85. Back when I was a kid, one of my first soldering projects was to replace a capacitor in the TI-85. At the time, all I knew is that the change would make it run faster. I didn’t know why I just knew it worked.

Today, I now know that capacitor was part of an RC oscillator for the Z80 CPU. It clocked the processor. By putting in a lower value, such as 2.2 or 4.7 pF, the calculator would speed up. The trade-off, of course, is that it means the batteries drain faster! But hey, before someone created Zshell, this was the only way to make Breakout run fast.

Of course, the focus of the episode is the gear from Weller. So please, hit-up element14 and check that stuff out. You can also find the polls I mention at the end of the video there.

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Soldering Tool Upgrade Paths

element14 - Workbench Wednesdays

Right after the digital multimeter, or DMM, a soldering iron is a must-have tool for electronics work. Like most tools, there is a vast variety of options available. In this episode of element14’s Workbench Wednesdays, I look at a range of instruments from Weller. They offer everything from a cheap $10 “fire starter” (sorry, it is what we call them!) all the way up to a full-blown surface mount rework station.

Whether you don’t have a soldering iron or you have a  $100 station, this video will show you options to consider when thinking about an upgrade.

After you watch the video, head over to element14 and tell me for you favorite solder tips! (Or your most burning questions!)

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Answering BJT questions with Karen on element14’s The Learning Circuit

element14's The Learning Circuit

Over on element14, Karen hosts The Learning Circuit. It is a tutorial show geared towards learning STEM basics. So far she has covered subjects like soldering, diodes, and how to make a DIY electromagnet. She did a great job on introducing BJTs and how they work. While I thought she provided a clear explanation of the internal workings, some members of the element14 community still had questions.

She invited me on to revisit BJTs and transistors to (hopefully) clarify the connection between how transistors physically work and how to use them.


Looking through my parts boxes, I have counted at least 15 distinct “Arduino boards” in my collection. Either they are variants of the Uno form factor or they have different processors from the 8-bit boards. That number easily goes to 30 if I include boards with just the “Arduino header” on them. This pile of microcontrollers got me thinking, how does anyone ever choose the right board?

For example, I have had several people tell me the ESP32 is the “ultimate Arduino.” But is it? Well, yes and no. Extra hardware you do not need can lead to complexity and unexpected behavior. When using an advanced module like the ESP32, it is important to learn how to use sleep modes to limit current consumption, especially for battery applications. But if you need WiFi, Bluetooth, I2C, SPI, UART, and high-performance processing, capacitive touch, GPIO, and analog inputs then the ESP32 is an obvious choice.

As for the other boards, I have written a guide to picking the right Arduino. You can find it over on the Hackster.io blog.

Read: Picking an Arduino

Appearance: How to pick from all the Arduino boards
Outlet: Hackster.io Blog
Format: Magazine

I have been soldering circuits for twenty-six years. Well, except for the last 6 weeks. I have had a Weller Zero Smog EL fume extraction unit in my lab. It has changed the way I solder. When I first used it, I thought “yes, this is nice. But not a necessity.” Then the other day I didn’t feel like moving the extractor to my secondary workbench. I was immediately irritated with myself for being lazy. The smoke was so annoying. I don’t know what else changed me so quickly.

The unit under test is the Weller Zero Smog EL Fume Extraction Kit. They sent it to me in partnership with element14 as a Roadtest review. (My previous review was on the 10 MHz Picoscope.)

Read Full Review on element14

Appearance: Weller Zero Smog EL Review on element14
Outlet: element14
Format: Other

Signetics Write Only Memory 25120 Datasheet


Signetics 25120 Page 1-torn

Signetics started as an IC manufacturer. In 1975 they were bought by Philips Semiconductors, which is now NXP. Interestingly the address in the datasheet, I think, was the original site. Today, it’s home to a Lowe’s Home Improvement Store. According to this Wikipedia article, it was created by John “Jack” Curtis. Apparently, it was included in a real Signetics catalog as a joke! Imagine that happening today. Additional information about the joke is available on sigwom.com. (Which may be written by Jack himself, not entirely sure.)

Download Signetics 25120 WOM Datasheet


2017’s Best Bald Engineer Tutorials, Articles, and Reviews

The popular tutorials, links, and videos fans watched most.

2017 Enginerd Review

As 2017 comes to a close, I looked back to see what readers made the most popular. It was an exciting year. The Arduino family came back together, Adafruit trolled the internet with rumors of a RadioShack buy out, and for me, I changed jobs.

Project wise I got my RetroPie SNES build completed, using an old Super Famicom case. This case is one I bought in Japan for 500 yen (about $5.) This work also led me to discuss voltage divider circuits. And I looked at a couple of scopes.

In case you missed it, here is what you as a reader found interesting over the past year.

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