Semiconductor Measurements | Workbench Wednesdays Review

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When it comes to transistors, there are only so many things a multimeter can measure. The DCA Pro from PEAK Electronics makes short work of testing parts like a transistor. This small device can determine pinout, component type, and essential parameters in a matter of seconds. Not only that, but it can be connected to a (Windows) PC and draw parameter curves. Check out the video review to see how the device and software works. Then head over to the element14 page where you can download a zip file full of example parts I measured for you. The free to download software can open them.

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Measuring ESR with the PEAK ESR70 | Workbench Wednesdays Review

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There are three capacitor measurements you need to know how to make: capacitance, leakage current, and equivalent series resistance. Capacitance is easy to measure if you have a current limited supply or can use a resistor. Apply a voltage, then time how long it takes to charge-up. You might need to use an oscilloscope or even an Arduino for the second part.  Leakage current is the easiest of the three, apply a voltage (ideally through a resistor) for a few minutes, and then measure the current. ESR requires some special tricks. Since it is the resistance of the “wires” connecting to the capacitive element’s anode and code, you have to measure resistance without charging up the capacitor. (Otherwise, you get leakage.)

In the post Measuring Aluminum Electrolytic Capacitor’s ESR, I go through those methods in more detail. I also introduce the PEAK Electronics ESR70. It’s a pocket-sized instrument that measures both Capacitance and ESR. There’s a button you can touch, or it detects when a new capacitor is connected. Check out my Workbench Wednesdays review where I go into depth about how the meter works (and whether or not I like it.) Oh one bonus feature, it works while in-circuit!

As of this post, it has been almost six years since I first wrote about capacitors on my blog. The article was the Arduino GSM Shield’s capacitor has a serious design flaw. Wow, how time passes.

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Bald Engineer’s ESD Must-Haves | Workbench Wednesdays

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Electrostatic Discharge (ESD) damage can occur without you knowing it. That’s bad. However, the good news is that with little effort you can prevent it. Duratool has a kit of the most common ESD tools for any electronics workbench. It includes a large mat, grounding cable, wrist strap, ESD-safe cleaner, and a simple electronic tester. Don’t get shocked by ESD; add these simple tools to prevent it.

This review is on a kit that includes:

  • Large ESD Mat
  • Ground Cable
  • Wrist Strap
  • Wrist Strap Tester
  • ESD Mat Cleaner

Even if you aren’t interested in ESD, you might want to watch the first 30 seconds. 🙂

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Tenma Portable Hand Held Supply – Workbench Wednesdays

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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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Health and Solder Fumes – Workbench Wednesdays

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An overlooked danger of electronics soldering is the fumes. While the smell and smoke may not be pleasant, the chemicals in the fumes can be harmful. Is solder made with lead(Pb) your only concern? Learn about where lead-free solder came from, what different flux types mean, and two ways to keep your air (and your lungs clean.)

In the video, I show a cheap “smoke eater” and a professional fume extractor. There is a cost difference of $50 and $700 between the two. However, either is better than having nothing.

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Surface Mount Rework Tools – Workbench Wednesdays

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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.


What is the Apple IIgs? – AddOhms Live Clip

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During a live stream, I was asked: “What is the Apple IIgs?” In this AddOhms Live Twitch Clip, I answer the question.

The Apple IIgs was the last of the highly successful Apple II line of computers. The “GS” stood for “graphics” and “sound.” Compared to previous Apple II computers, the IIgs was a fully 16-bit machine. When connected to its proprietary RGB monitor, it rendered a gorgeous display. Sadly, not much software took advantage of the improved graphics and sound capabilities. The IIgs was fully backward compatible with the older 8-bit line of Apple II computers. Its compatibility was so good that most IIgs users only used it in the compatibility mode.

How did the Apple IIgs achieve backward compatibility?

The IIgs contains an ASIC called the “MEGA-II.” (Which has nothing to do with the “Mega” Arduino boards.) It includes all of the individual logic chips from the original Apple II design as a single IC. Well, in addition to that IC you also need to add a CPU, RAM, and a ROM.

In my opinion, the Apple IIgs is best of the Apple IIs. In fact, of computers in that era, it is my overall favorite. When I got the IIgs, it replaced my previous pick: a Macintosh SE/30.

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 (Which may be written by Jack himself, not entirely sure.)

Download Signetics 25120 WOM Datasheet