Meet Our Team: Sam Zerbib

Sam Zerbib joined the Circuit Specialists team in January 2015 and will be providing customer support as well as testing our test equipment and other products. More importantly, though, Sam is in charge of new product selection. Circuit Specialists is expanding into new and exciting fields like 3D printing — check out our new premium 3D printer filament — and we want your input. What new products would you like to see added to our website?

Sam studied mechanical engineering at Northern Arizona University where he specialized in thermodynamics, electronics, and mechanical engineering design, among other topics. In the past he’s worked with architects and other mechanical engineers designing heavy-duty HVAC kitchen ventilation systems.

Please send your ideas concerning new products to and he’ll get back to you as soon as possible. He looks forward to hearing from you.

Sam Zerbib portrait

Inventory Alert: Our Ship Has Finally Come In!

You may have noticed that many of our best-selling products have been out of stock in the last couple months. Circuit Specialists, along with thousands of other businesses across the country, has been seriously impacted by the West Coast port slowdown. Thankfully the slowdown has ended and we are beginning to recover and receive much needed shipments of new products. We sincerely apologize for any inconvenience to you.

If you weren’t already aware, the slowdown was a result of labor negotiations between the International Longshore and Warehouse Union and waterfront employers. The failure of both sides to reach a working contract has had a tremendous impact on the timely shipment of product into the United States. We are working hard on our end to overcome the delays this slowdown has caused to our operations.

That being said, Circuit Specialists is happy to announce that we have received our first full container shipment to our new location in Tempe, Arizona.


The West Coast ports are back in operation and Circuit Specialists has received our first full container at our new location. Fancy banner, huh?

The truck arrived early Monday morning, March 2nd, and backed into our dock. Our crew was ready and waiting to unload the full container containing power supplies and many other popular products. At our old location, we would have to unload the container onto pallets in our parking lot, sort the load, and then bring boxes into the warehouse in small lots. Yeah, that sucked.


With the new warehouse layout, we are able to quickly unload a container directly into the warehouse, where it can be sorted much faster and with less effort.


With much wider isles and a single warehouse area, Circuit Specialists expects to be able to process inbound containers much more efficiently than ever before, enabling us to ship your orders faster.


Circuit Specialists is also working hard to keep more inventory in stock in order to minimize the impact of events like the recent port slowdown.

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Using a USB Flash Drive with Hantek 1000 Series Oscilloscopes

Hantek 1000 series digital storage oscilloscopes feature the ability to store data and screen captures to a USB flash drive. However, there are limitations to the size of the flash drive that will function with your oscilloscope.

First, for the oscilloscope to recognize the flash drive it must be formatted as FAT32. Formatting with FAT32 is pretty straightforward on most operating systems.


Selecting FAT32 on a Windows computer.

We have also found that Hantek 1000 series oscilloscopes will not recognize a flash drive larger than 4 GB. We have tried both 8 and 16 GB flash drives with no success and suspect that the same results will be found with larger flash drives.


Select MS-DOS (FAT) on a Mac.

The same FAT32 requirement applies to USB hard drives as well, though the availability of traditional hard drives that small is rather limited these days.


Select FAT32 when using Linux.

Once the USB flash drive is formatted as FAT32 the Hantek 1000 series digital storage oscilloscopes will recognize it and you can save data and screen captures to it for use on a personal computer.

This formatting restriction also applies to a using a flash drive to update the firmware on the 1000 series oscilloscopes as well as loading and saving waveform data. These oscilloscopes enable you to save and recall either scope set up (vertical, horizontal, and trigger settings) or captured waveforms, which is helpful in subsequent analysis of measured signals and comparisons with new measurements. Waveforms may be saved as graphic images (JPEG or BMP) or in CSV format so that you can post-process the captured waveform data.


Hantek 1000 series oscilloscope file screen

How to Use an Enclosed Switching Power Supply

There are many applications for an enclosed switching power supply — for example, you can build a 3D printer in which the power supply controls the stepper motor used to position the print head. There are a wide range of types of switching power supplies with different voltages and current ratings to suit a variety of applications, including supplying power to the stepper motors in CNC machines.


A typical enclosed switching power supply

Another popular application for switching power supplies is in LED lighting. Simply select the appropriate voltage and current rating for the LED lighting module and connect it to the screw terminals on the power output of the power supply. Depending on the output current rating of your power supply, you can connect several LED modules in parallel to the same power supply, reducing the number of 110V connections and the overall cost.

These types of lights are great for lighting a workbench. You can find LED light modules with an aluminum channel and magnets that you can attach to the underside of your workbench’s shelf (see below). Attach three or four of these modules to the workbench and wire them all together, connecting them to a single power supply. Then connect a simple line cord to the unit and plug it into a power strip. Whenever the power strip is turned on all of the LED lights will come on. You can easily reposition magnetic lights like these to suit whatever project you’re working on.


Enclosed switching power supplies are ideal for powering LED lights.

5, 24, and 48 volt switching power supplies are frequently used in telecommunications. A 5 volt power supply is a perfect power source for power over Ethernet (PoE) injectors for the IP-based telephone equipment used in many business telephone systems. These power supplies are readily available, making it fast and easy to replace a failed power supply. They are also very cost-effective.


Using an enclosed switching power supply to supply 5 volts to a PoE injector in a telephone system.

Circuit Specialists offers a large assortment of enclosed switching power supplies rated from 3.3 to 48 volts with current ratings up to 80 Amps.

Shop enclosed switching power supplies

3D Printing: Adding, Not Subtracting

Prototyping is an essential part of the design process and until the recent invention of 3D printing, it was time consuming and could be prohibitively expensive. Designers were limited to using computer models for visualization and product development. The 3D printer is a revolution in the design and iteration process; intricate computer models and scanned physical objects can be replicated in plastic without many of the tools and materials costs of CNC mills and lathes. When building from a mill or lathe a person must begin with a block of material, often representing over two times the final product volume, and then subtract material. 3D printing eliminates much of that waste as plastic filament is melted and adds material in thin layers.

There is a seemingly endless number of 3D printer manufacturers and models, from high-precision printers for thousands of dollars to DIY printers that you can build for less than $100. Some common features of these printers are stepper motors, stepper motor controllers, power supplies, and 3D filament. 3D printers often use NEMA 17 stepper motors. 1.75mm diameter 3D filament is widely used by many different 3D printers as it is light and flexible, preventing jams at the nozzle. Thicker filaments require stepper motors that supply higher torques, such as our 4.2 kg-cm NEMA 17 stepper motor.

3D printer filament

PLA 3D printer filament is available in black, blue, brown, glow-in-the-dark, gold, green, gray, navy, orange, lime, pink, purple, light skin, translucent, red, silver, white, and yellow.

PLA vs ABS Filament

PLA (polylactic acid) is printed at a lower temperature and is less prone to warping, which makes it better for printing without a heated printer bed. Because it is derived from sugar, PLA gives off a semi-sweet smell during printing. PLA has a lower melting temperature than ABS (acrylonitrile butadiene styrene) and it is also considered more environmentally friendly, since it is derived from plants (i.e. it is a renewable resource) and biodegradable. Keep in mind that PLA’s low melting temperature makes it unsuitable for a part that will be exposed to high heat. PLA flows more smoothly than ABS, providing precise and fast printing.

ABS is a stronger plastic overall and as a result can be sanded or machined. It is printed around 225°C (PLA is printed at about 200°C). ABS is also soluble in acetone, meaning you can give a shiny finish to a 3D printed part by applying a few drops of acetone to the surface. ABS will be more resilient than PLA for a part that is exposed to the elements and high temperatures.

HIPS (high-impact polystyrene) filament is another interesting option. If you have a dual extruder, you can print with ABS and HIPS and then dissolve the HIPS with Limonene, enabling you to create intricate shapes and voids that would be impossible to make without support.

Shop PLA 3D filament

Circuit Specialists has moved

After nearly twenty-five years at our store in Mesa, Arizona, Circuit Specialists has moved to a new location.

We are now located at 819 West Fairmont Drive Suite 2 in Tempe, Arizona, closer to the heart of the Phoenix metropolitan area, which we hope will be more convenient to our local customers. Our new building has a much larger warehouse area with two loading dock bays, enabling us to receive much larger inbound shipments of merchandise.


Circuit Specialists is now at 819 W Fairmont Dr Ste 2, Tempe, AZ 85282

Our old warehouse was split into two separate areas, hindering our ability to find and pick orders. This new warehouse and dock layout will facilitate a much more efficient flow of orders to our customers and will also allow us to increase the number of products we stock, like our newest arrival of premium 3D printer filament, available in a wide variety of vivid colors. Circuit Specialists is always striving to provide faster, more efficient service for our customers without sacrificing accuracy.

If you are ever in the Phoenix metropolitan area, feel free to stop by. Our store hours remain 8:00 AM to 5:00 PM, Monday through Friday. We are on the south side of Fairmont Drive, two blocks north of Southern Avenue, between Hardy Drive on the west and Roosevelt Street on the east.

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Using the UBA-9290 RF Field Strength Analyzer to Test for EMC Compatibility

2.9 GHz field strength analyzer

The UBA-9290 is a handheld portable radio frequency (RF) field strength analyzer with spectrum capability that you can use to perform a variety of RF signal measurements including electromagnetic (EMC) compliance. All electronic products — including switching power supplies, which are commonly used in almost all types of electronic equipment — must conform to specific regulations with regard to susceptibility and emissions of RF interference. This article will discuss how to use an RF field strength analyzer to perform measurements related to EMC compliance.

The aim of the EMC regulations are to ensure that electromagnetic disturbance generated by electrical or electronic equipment doesn’t reach levels that would prevent radio, telecommunications, and other equipment from working properly. The frequency range required to comply with the EMC directive is from 150 Khz to 30 Mhz for conducted emissions and from 30 Mhz to 1 Ghz for radiated emissions. The frequency range of the UBA-9290 RF frequency analyzer is specified from 100 Khz to 2.9 Ghz, making it ideal for performing these measurements.

Conducted emissions refer to RF signals that are being generated by the device under test that have the potential for being conducted out of the unit via cords and cables. The device under test is first placed on an insulated table above a ground plane, and then you monitor the RF signal levels of any necessary cords or cables with the UBA-9290. RF signals in the range of 150 Khz to 30 Mhz must be below the maximum values in amplitude. Since the UBA-9290 has an input sensitivity of -117 dBm, it will easily perform the required measurements. Any RF levels above the values specified in the directive must be reduced.

Radiated measurements refer to RF signals that are radiated from the device through the air. The UBA-9290 must be placed a specified distance from the device under test and positioned at various heights so as to maximize the received signal. The device under test must also be rotated 360 degrees so as to produce maximum RF signal levels. The acceptable frequency range for radiated emissions is 30 Mhz to 1 Ghz.

The UBA-9290 may be connected to various antennas or probes to facilitate the required measurements specified in the EMC directive. These can be near current probes, field probes, and dipole-type antennas. These probes and antennas can be purchased commercially or fabricated in the laboratory.

The UBA-9290 RF field strength analyzer provides a relatively low-priced method of performing initial compliance testing for the EMC directive. Its wide frequency range and excellent signal sensitivity make it perfect for performing the required conducted and radiated emissions measurements required to comply with this directive.

2.9 GHz Field Strength Analyzer

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2.9 GHz Field Strength Analyzer

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An introduction to Heat Shrink Tubing

Heat shrink tubing is ideal for splicing wires and protecting electrical connections and comes in a plethora of sizes to suit most applications. You can also find a variety of tools that make it even easier to use.

Most heat shrink tubing has a 2-to-1 shrink ratio, meaning you can shrink a tube with a one inch diameter to half an inch in diameter. Once you’ve shrunk the tube it remains at that size, molding itself to whatever it is surrounding. This shrinking and molding action helps protect wire splices and connections from the elements as well as from inadvertent electrical shorts to any metallic objects that might come in contact with the connection.


Heat shrink tubing can be shrunk in several ways, the most effective being a hot-air gun. Hot-air guns are quite similar to the blow dryer you use to dry your luxurious locks of hair, but hot-air guns produce much higher temperatures. People often use small butane torches for shrinking heat shrink tubing as well as they are often smaller and much more portable than hot-air guns. You must be very careful when using either a hot-air gun or a butane torch around flammable liquids and gasses.


The size of the heat shrink is an important factor to consider. Before joining two wires, place the desired size and length of tubing over the end of one of the wires. Once the joint has been made you will then slide the heat shrink tubing over the joint and apply heat to it.  Carefully apply even heat to cover and protect the joint.

It is a good idea to practice on a few different sizes and types of joints, splices, and connectors to get a feel for how much heat to apply with the selected size of tubing and heat source before attempting to use this technique in your projects. This will enable you to create much more uniform and functional heat shrink applications that not only protect the wiring, but look more professional than if they were done with simple electrical tape.

Programmable DC Electronic Load Applications

Programmable DC electronic loads are useful for a variety of test and measurement applications including battery testing and characterization as well as testing power supplies and solar panels. We will discuss these three types of applications in this article.

A programmable DC electronic load is ideally suited for testing any battery, especially rechargeable lead-acid, NiMH, NiCad, and Li-ion battery packs. The ability to set a minimum voltage level enables unsupervised discharge of the battery pack under test. The type of battery you are testing will determine the parameters you will program into the electronic load. These parameters include end of discharge voltage and discharge current. Some higher-end electronic loads feature an automatic battery testing feature that automates battery testing, but you can use any DC electronic load for this operation.

DC power supply testing is the most common use for an electronic load. Voltage and current output values can be verified as well as current limit and constant current operation. You can easily measure power and regulation with an electronic load. If the load has a computer interface, you can log temperature and time variance information for future reference or for documentation requirements.

As solar power becomes more affordable and popular, DC electronic loads have become an indispensable tool for characterizing and testing photovoltaic solar panels. For this type of test the load should be capable of constant voltage operation, which enables you to step through the output voltage value while measuring the resultant output current. Constant voltage operation provides you with a current versus voltage (I-V) curve that shows all of the solar panel’s characteristics, including the maximum power point at which the solar panel is operating most efficiently.

Although we have outlined several common uses for a programmable DC electronic load, this list is by no means exhaustive. Transient load testing and power supply recovery are also possible with some of the more complex electronic loads available at Circuit Specialists.

A Look Back at Circuit Specialists

When Circuit Specialists was established in Darrel and Leon Thorpe’s garage in Scottsdale, Arizona, all the way back in 1971, no one expected us to be where we are now.

By September of 1971 Circuit Specialists had moved out of the garage and into a small office and began publishing a mail order catalog called “Semiconductor SuperMart.” This catalog featured resistors, capacitors, diodes, chokes, coils, and integrated circuits (which had just been invented) as well as other products for electronics hobbyists and do-it-yourselfers.

In the Fall of 1972 Circuit Specialists expanded into the brick-and-mortar world by opening a retail outlet in Tempe, Arizona. Circuit Specialists became a Lafayette Radio franchise and was located right next door to a Radio Shack. In addition to the electronic parts line from the “Semiconductor SuperMart,” Circuit Specialists offered quality stereo equipment, police scanners, and CB radios courtesy of Lafayette Radio. We soon became a regional distributor. One of our current employees who joined Circuit Specialists in 1991 was even a regular customer, buying his first police scanner from Leon Thorpe back in the early ’70s.

In 1987 Circuit Specialists bought its first computer for inventory and accounting. In just a few years we started offering products online via the new realm of the Internet. Soon after that Circuit Specialists moved into the twelve thousand square foot retail storefront and warehouse in Mesa, Arizona where we continue to do business today.

Circuit Specialists printed countless paper catalogs over the years, but with the exponential growth of the Internet we decided to stop printing paper catalogs in the early 2000s and have become primarily an online retailer, although our retail storefront is still open for the convenience of our local customers.

In order to increase our product line Wayne Thorpe, then president of Circuit Specialists, made his first trip overseas to initiate direct importation of electronic equipment and supplies in 1986. By 2001 Circuit Specialists had opened an international office overseas, which enabled us to rapidly expand into soldering equipment, power supplies, and test equipment. Circuit Specialists is able to keep the price of our products remarkably low by cutting out all the middlemen.

We usually make at least one or two trips overseas each year to source new products and to maintain the close contact that we have established over the years with our suppliers. We feel this is an important part of doing business, as it allows us to have a much closer relationship with our suppliers, which benefits our customers.

For over forty years Circuit Specialists has been selling quality electronic components, equipment, and accessories and we will continue striving to provide you with the finest products at the lowest prices.

In February of 2015 we moved from our location in Mesa, Arizona to a new location at 819 W Fairmont Dr Ste 2 in Tempe Arizona., offering our customers the benefit of dealing with an established US-based company and helping them avoid the pitfalls that commonly occur when dealing with overseas sellers themselves. In addition to our large selection of electronic components, we also continue to offer our educational electronic lab kitting service for schools.

Simply smart circuitry since 1971.