Author Archives: vernon

Moore’s Law and Data Storage

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In 1987, A 10MB Hard Disk Drive for the 8 Bit IBM XT PC could be purchased for about $500.00, a steep decline in cost over the price when first introduced about 5 years earlier. Today, no current mass storage media with such a small capacity is produced. The smallest capacity for a USB Flash “Thumb Drive” sold these days is 1GB and they are under $10.00 in all but the most highly marked up locations, but why even bother when 16GB can be had for less than $10.00 just about anywhere too. But wait there’s more… A common reasonably priced capacity for these things today (February 2014) is 64GB at $30.00, so let’s use that for comparison.

Keep in mind that 1 GB is 1,000 MB, The 64GB USB Thumb Drive has 64,000 MB…

1987: 10MB HDD ~$500.00 = $50.00/MB.
2014: 64GB USB ~$30.00 = $0.00046875/MB (less 5 ten thousandths of a cent per Megabyte).

What does this mean? For this comparison the cost per MB “Megabyte” (1 Million Bytes) [1 Million units of 8 bit data] has decreased by a factor of more than 106,000.

How about a comparison of what you get for the same price? OK so the USB Thumb Drive comparison was chosen for both capacity and performance (Even though it’s about the lowest performing current product it’s still much faster than that old 1987 HDD). Then what does one get for ~$500.00 today? A 1TB SSD can be bought for ~$500.00. That’s 1,000 GB or 1,000,000 MB (it’s One Trillion Bytes). Cost comparison…

1987: 10MB HDD ~$500.00 = $50.00/MB.
2014: 1TB SSD ~$550.00 = $0.00000000055/MB (0.55 billionths of a cent per Megabyte).

As for performance? A comparison is difficult. The 1987 Hard Drive had an “Average Seek Time” of 85ms. The 2014 SSD does not have moving parts and “Seek Time” is largely irrelevant for the speed of electrons over a few mm distance. A more fair comparison is Data Transfer Rate…

1987: 10MB HDD 5MB/second.
2014: 1TB SSD 520MB/second.

Therefore, cost has dropped by about one Trillion percent and performance has increased by 10,400%.

Also the SSD is inherently durable while the old HDD was very fragile. Projected lifespan is measured in MTBF “Mean Time Before Failure” (a weighted average of the typical endurance of the product)…

1987: 10MB HDD 11,000 Hours (1.25 years) They actually typically lasted 10 to 15 years.
2014: 1TB SSD 1,500,000 Hours (171 Years).

In Summary: Most factors have been have been close to Moore’s law (Doubling in performance or capacity every 18 months) or a bit better, cost has dropped at a far more rapid pace than that!

Aluminum Wiring Fire Hazard

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If your home was built in or around 1970 to 1974, there is a chance it may have been built with aluminum (Aluminium if you are from the UK) electrical wiring. If your home is wired with aluminum, it has probably had a retrofit by now, no longer has electricity, or has already burned down. In our case there are some circuits that were either skipped or poorly done in the original retrofit and they have caused a few spooky and frightening events.

Aluminum Wire

Our house was built in 1970 and was “allegedly” retrofitted under warranty sometime before 1984 when last sold. The procedure was to verify that all exposed connections were at least covered in a dielectric grease to prevent oxidation. A better method is to extend all aluminum wire ends with copper pigtails using wire nuts filled with the dielectric grease. That’s what I do when I find one of these hazardous connections. In the image above, the source side neutral wire shows some extreme arcing evidence with the built up fingers and charring of the wire and outlet body plastic. This convenience outlet was only used to power a night light, but a downstream outlet in the same circuit is used more extensively. The downstream outlet lost power first. An inspection of that outlet did not reveal the source, neither did the subsequent inspection of the circuit breaker (although it appeared to be well past it’s maximum useful life, see image below). The search then led to this outlet.

Old Breaker

How does this happen? Well, all metals oxidize when exposed to air. Aluminum oxide is white or nearly transparent but more importantly it is non conductive. As the aluminum wire oxidizes under the terminal screw. It begins to develop a resistance at the connection. The now resistive junction generates heat (and a small voltage drop). Heating softens the wire. The softened wire can stretch under the mechanical stress of lateral tension and/or the pressure of the terminal screw. As the wire stretches, it becomes thinner. As the wire becomes thinner, it becomes loose. Once the connection is loose enough, it will begin arcing when current flows through. Once it begins arcing, the entire process accelerates. In summary: Aluminum wiring should never have been allowed!

Screen Sharing on a MAC (Alternative Method)

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Many are familiar with the “Screen Sharing” feature in MAC OS X. It allows you to connect remotely to the desktop of another MAC when that other MAC is accessible as a network share and has the Screen Sharing feature enabled under the Sharing setting in System Preferences. A “Share Screen” button will be displayed to the left of the connnect/disconnect button for the network computer in the upper right of the finder window when that remote computer is selected in the network page or in the sidebar.

Unless… If you have a network with multiple subnets, routers and/or firewalls. Network discovery services like DNS and Bonjour may not get through these boundaries. Then you may not see the “Share Screen” button, so what do you do?

Watch the video for an alternative method…

This method uses Safari to launch Screen Sharing via the http port.

bGeigie Nano part 1 (unboxing the kit)

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The bGeigie nano is an updated and smaller version of the original bGeigie nuclear radiation monitor and geo-referenced radiation mapping device. These devices were developed by the Safecast organization to provide radiation monitoring and data mapping by and for the public.

The kits were offered for pre-order recently, so I signed up on the waiting list and was able to get one in the first batch of kits provided in the US by International Medcom. The kit arrived at the end of June (they sent a resistor to change out an incorrect value part in the kit a few days later) and It’s finally time to open the box after about a month on the shelf.

The first video in a series on the bGeigie nano, unboxing and discovering what parts are in the kit.

To get your own bGeigie nano kit, see this page at International Medcom.

Support Engineer LLC and Save on Web Hosting with a free discount code from Dreamhost!

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Do you need a website? Where does the website Engineer come from? It’s on a server at Dreamhost. How? Well to start with, a Web Hosting account from a reliable provider is needed. Engineer LLC uses Dreamhost for web hosting and domain registration services. Dreamhost is a serious no-nonsense web hosting business with several distinct advantages! The cost is low, the reliability is unbeatable, they are Green, Socially responsible and a little bit irreverent (and maybe not as sleazy as some bigger hosting companies). They are a mid-size company that started small and remember where they come from. This blog you are now reading is hosted on Dreamhost. New customers can use the promo code FREE3MONTHS to receive an additional discount of 3 months free when signing up for a year or 6 months free (3 free months per year for 2 years) when you sign up for two years, compliments of Engineer LLC. Create a new account with Dreamhost and remember to use the free discount code FREE3MONTHS. Engineer LLC gets a small referral fee for each new signup that helps offset the cost of bringing you this Website!

Hey everyone! Here’s another one of my favorite Electrical Engineering YouTube Channels

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As is common with the Internet, a while back, I stumbled upon the YouTube channel of “Photon” when reading some postings of another YouTube favorite, toddfun.com. Photon is a consummate master of High Voltage and “Releasing the Magic Smoke”. But wait there’s more! Photon’s deadpan (British Dry Humor) delivery is absolutely hilarious. Quite educational (and safe when viewed online). Fun for all…

1983 D.C. Johnson FAC-1 Revision C

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This is a 1983 D.C. Johnson FAC-1 Revision C. It works like new with just few minor repairs. That’s 30 years in service and now ready for many more. Not bad!

The D.C. Johnson FAC-1 is an Air/Fuel control unit similar in function to the OEM “Lambda Controller” units for European cars equipped with mechanical fuel injection systems. It was designed to retrofit cars made for sale in the European market before emissions regulations were instituted, to meet United States specifications after they were imported into the United States of America.

Electromechanical Timer Teardown

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This basic electromechanical timer was installed in a low voltage landscape lighting transformer.  It lasted a couple months short of 10 years.  I opened it up to see and show how it was designed and why it failed.  The clock motor was still working.  The contacts got eroded enough over the years that they were no longer closing.

A good example of simple and low cost electromechanical product design.

A Serial Bootloader for Microchip 8 bit PIC Embedded Designs: Microchip Application Note AN1310

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This article introduces the reader to a set of up to date Serial Bootloader tools for Microchip 8 bit PIC series products that we frequently use in electronic designs featuring an 8 bit embedded MCU (Micro Controller Unit).

So what is a Serial Bootloader and why would anyone want it?

In some products that use an MCU it may be advantageous to allow the program to be updated in the field or at a service shop without the specialized programming gear needed to completely reprogram it. For this purpose the MCU is equipped with a small primary program whose sole purpose is to facilitate updating of the main device application program.  In embedded systems this is sometimes referred to as a “Bootloader Stub” since it is often located at the beginning or end of the program memory space, and is the first code to execute on start or reset.  When the device starts, the Bootloader checks for a special state or instruction.  If that object is present, the Bootloader waits to download and overwrite the Application Program with an update.  Otherwise the device continues on to execute the full Application Program.  Some such devices have a USB port that can be used as the communications for this but it is less common than other serial port types that can be implemented at lower cost. One of the most common serial port types on low cost embedded designs is the venerable RS-232 port. In fact, many different MCU devices have one or more built in UART devices (direct support for RS-232) while just a handful build in the more complex USB port.

For example: recently tasked with redesigning a controller PCB for an existing product, there was no need or desire to change the interfaces, only update the components that were obsolete. One of the obsolete components was the Microchip MCU, a 40 PIN DIP with insufficient Flash memory for program updates and a shortage of digital I/O. It was replaced by an 80 pin TQFP variant with more memory space in all 3 categories (Flash, RAM and EEPROM) more I/O of course (to eliminate the previous I/O sharing scheme and provide for expansion) and perhaps most important at a lower cost than the old part it replaces. A dedicated ICSP (In Circuit Serial Programming) port replaces the practice of burning the old DIP parts in in an old EEPROM programmer appliance. The product also uses an RS-232 port to communicate with a control computer. In this case, it was decided to leverage the existing RS-232 port in the design for firmware maintenance. The larger Flash space of the new MCU allowed adding the Serial Bootloader feature to eliminate the need for any dedicated programmer equipment when updating units already programmed at least once. All that is needed is a PC to run the AN1310 PC Bootloader application equipped with a RS-232 serial port, an established serial link between the computer and device to be programmed and the program update in the form of a .hex file.

The Application Note from Microchip, AN1310 provides all of the resources needed to accomplish the addition and operation of the Serial Bootloader with many variants of the PIC16F and PIC18F 8 bit MCU families having an available UART port.

Microchip AN1310

Windows Server 2012 Essentials First Look

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Update November 2, 2012: The video is now available with Captions in several languages. Just select the CC icon to include the Closed Caption Text in your favorite language.

Windows Server 2012 Essentials First Look. A quick tour of Microsoft Windows Server 2012 Essentials, the latest Server OS from Microsoft as of this post.

I am evaluating this new basic version of Windows Server. It was released to manufacturing (RTM) on October 9, 2012 and released to MSDN Subscibers on October 10, 2012.

Posted by Vernon, Engineer LLC October 19, 2012