Tag Archives: measurement

A Workspace for Radio & Metrology Projects

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Ralph Berres, a television technician in Germany, created an exemplary design space in his house for working on projects relating to his two main technical interests: amateur radio and metrology (the science of measurement). He even builds his own measurement equipment for his bench.

Ralph Berres built this workspace for his radio and metrology projects

“I am a licensed radio amateur with the call sign DF6WU… My hobby is high-frequency and low-frequency metrology,” Berres wrote in his submission.

Amateur radio is popular among Circuit Cellar readers. Countless electrical engineers and technical DIYers I’ve met or worked with during the past few years are amateur radio operators. Some got involved in radio during childhood. Others obtained radio licenses more recently. For instance, Rebecca Yang of Tymkrs.com chronicled the process in late 2011. Check it out: http://youtu.be/9HfmyiHTWZI and http://tymkrs.tumblr.com/.

Do you want to share images of your workspace, hackspace, or “circuit cellar” with the world? Click here to email us your images and workspace info.

 

Weekly Elektor Wrap Up: Laser, Digital Peak Level Meter, & “Wolverine” MCU

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It’s Friday, so it’s time for a review of Elektor news and content. Among the numerous interesting things Elektor covered this week were a laser project, a digital peak level meter for audio engineering enthusiasts, and an exciting new ultra-low-power MCU.

Are you an embedded designer who wants to start a laser project? Read about “the world’s smallest laser”:

What is the biggest constraint in creating tiny lasers? Pump power. Yes sir, all lasers require a certain amount of pump power from an outside source to begin emitting a coherent beam of light and the smaller a laser is, the greater the pump power needed to reach this state. The laser cavity consists of a tiny metal rod enclosed by a ring of metal-coated, quantum wells of semiconductor material. A team of researchers from the University of California has developed a technique that uses quantum electrodynamic effects in coaxial nanocavities to lower the amount of pump power needed. This allowed them to build the world’s smallest room-temperature, continuous wave laser. The whole device is only half a micron in diameter (human hair has on average a thickness of 50 micron).

The nanolaser design appears to be scalable – meaning that they could be shrunk to even smaller sizes – an important feature that would make it possible to harvest laser light from even smaller structures. Applications for such lasers could include tiny biochemical sensors or high-resolution displays, but the researchers are still working out the theory behind how these tiny lasers operate. They would also like to find a way to pump the lasers electrically instead of optically.

Be sure to check out Elektor’s laser projection project.

In other news, Elektor reached out to audio engineering-minded audio enthusiasts and presented an interesting project:

Are you an audio amateur hobbyist or professional? Do you try to avoid clipping in your recordings? To help you get your audio levels right, in January 2012 Elektor published a professional-quality peak level meter featuring 2x 40 LEDs, controlled by a powerful digital signal processor (DSP). As part of the eight-lesson course on Audio DSP, all the theory behind the meter was explained, and the accompanying source code was made available as a free download.

The DSP Board has been available for a while, and now we are proud to announce that the Digital Peak Level Meter is available as an Elektor quality kit for you to build. Although the meter was designed as an extension module for the Audio DSP board, it can be used with any microcontroller capable of providing SPI-compatible signals. So get your Peak Level Meter now and add a professional touch to your recording studio!

And lastly, on the MCU front, Elektor ran interesting piece about the Texas Instruments “Wolverine,” which should be available for sampling in June 2012:

Codenamed “Wolverine” for its aggressive power-saving technology, the improved ultra-low-power MSP430 microcontroller platform from Texas Instruments offers at least 50 % less power consumption than any other microcontroller in the industry: 360 nA real-time clock mode and less than 100 µA/MHz active power consumption. Typical battery powered applications spend as much as 99.9 % of their time in standby mode; Wolverine-based devices can consume as little as 360 nA in standby mode, more than doubling battery life.

Wolverine’s low power performance is made possible by using one unified ferromagnetic RAM (FRAM) for code and data instead of traditional Flash and SRAM memories, allowing them to consume 250 times less energy per bit compared to Flash- and EEPROM-based microcontrollers. Power consumption is further reduced thanks to an ultra low leakage  process technology that offers a 10x improvement in leakage and optimized mixed signal capabilities.

MSP430FR58xx microcontrollers based on the Wolverine technology platform will be available for sampling in June 2012.

Circuit Cellar and CircuitCellar.com are part of the Elektor group.

 

audioXpress: HP456A Current Probe Restoration

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Retro electronics (or “retronics”) projects are growing in popularity. Across the globe, professional engineers and DIYers alike are tweaking, updating, and hacking retro systems to create all sorts of innovative designs. Restoring and upgrading an old electronics tool, MCU-based design, or audio system can be a rewarding experience.

In the February 2012 issue of audioXpress magazine, Bill Reeve details how he restored a Hewlett-Packard 456A current probe (“Restoring the HP 456A Current Probe”). Here’s an abridged excerpt:

The restoration is finished and ready for cover installation (Soure: Bill Reeve AX 2/12)

The Hewlett-Packard 456A AC current probe is a treasure. It can be bought cheaply because many of the units sold were battery powered and all were designed with a now-out-of-date oscilloscope interface connector. However, when restored, the 456A is a fabulous addition to any test bench, matching the performance of more expensive modern instruments.

Released as a new product by the Hewlett-Packard Company in 1960, the 456A was HP’s first solid-state, stand-alone, clip-on current probe. Its elegantly designed amplifier uses two— then “state-of-the art”—PNP germanium transistors.

The Original Probe
In 1960, The Hewlett-Packard Journal (July-August, Vol. 11) proudly announced:

“This new probe measures current over the full range of the frequencies most commonly used in typical work—25~ to 20 megacycles—and over an amplitude range from below 0.5 mA to 1 A rms…The probe operates with an accompanying small amplifier…to convert the AC current being measured to a proportional voltage. This voltage can then be measured with a suitable oscilloscope or voltmeter. The current-to-voltage conversion factor is 1 mV/mA.”

The 456A operating and service manual is available at www.hparchive.com, but this scanned copy contains incorrectly annotated schematic values for R7 (should be 3300 Ω), R8 (should be 2700 Ω) and C5 (should be 0.01 μF).

Old battery-powered 456As are usually in excellent physical shape because when their batteries ran down these instruments were often shelved and forgotten. Another 456A advantage is that its probe head is wired directly to the amplifier, so they cannot be separated by surplus electronics dealers.

Restoration
Restoration of the 456A consists of three steps: replacing the old battery pack with DC power, restoring the amplifier electronics, and converting the obsolete oscilloscope banana plug interface to a BNC connector.

Step 1: Replace the old battery pack. Remove the two Phillips-head screws on the housing back to slide off the 456A’s cover. Re-thread the screws into the frame to keep them from getting lost. ….

Step 2: Restore the amplifier electronics. At this point, if you are happy with your current probe’s performance, you can skip the following upgrades, but these are five modifications you might need to perform to get your 456A working or improve its performance:

• Replace the electrolytic capacitors
• Replace the two germanium transistors
• Replace the 8-V breakdown diode (CR1)
• AC-couple the output
• Flow solder onto the printed circuit traces

Photo 6 is an annotated close-up of the amplifier’s single-sided printed circuit board. Following vacuum tube circuit convention, the +5 V is labeled “B+” and the –8 V is labeled “B–”. There are three electrolytic capacitors in the amplifier (see the horizontal silver cylinders in Photo 6), and their replacement is straightforward. ….

Photo 6: The amplifier's original printed circuit board (Source: Bill Reeve AX 2/12)

Step 3: Convert the oscilloscope interface to a BNC connector. This final modification can be performed one of three ways. Pomona electronics (visit the website pomonaelectronics.com) sells a female banana to male BNC adapter (Model 1296). You can cut the banana plug connector off the existing cable and attach a male BNC connector. This requires special tools.

You can replace the output cable with coax having one BNC end. This is a straightforward replacement. Photo 9 shows the new BNC output cable. …

Photo 9: BNC ouput cable installed (Source: Bill Reeve AX 2/12)

This restoration should make your 456A ready for another 50 years of service.

Note: The complete article appears in the February 2012 issue of audioXpress magazine. audioXpress magazine, like Circuit Cellar, is an Elektor group publication.