About C. J. Abate

C. J. Abate is Circuit Cellar's Editor in Chief. You can reach him at cabate@circuitcellar.com and @editor_cc.

Dutch Designer’s “Comfort Zone”

Check out this amusing workspace submission from Henk Stegeman who lives and works in The Netherlands (which is widely referred to as the land of Elektor). We especially like his Dutch-orange power strips, which stand out in relation to the muted grey, white, and black colors of his IT equipment and furniture. StegemanWorkspace

Some might call the space busy. Others might say it’s cramped. Stegeman referred to it his “comfort zone.” He must move and shift a lot of objects before he starts to design. But, hey, whatever works, right?

Hi,

Attached you picture of my workspace.
Where ? (you might ask.)
I just move the keyboard aside.
To where ?
Euuh… (good question)

Regards

Henk
The Netherlands

Visit Circuit Cellar‘s Workspace page for more write-ups and photos of engineering workbenches and tools from around the world!

Want to share your space? Email our editorial team pics and info about your spaces!

WIZnet Announces WIZ550io & W5500 Discounts at EELive

Today at EELive! in San Jose, CA, WIZnet announced a special promotion tied to the WIZnet Connect the Magic 2014 Design Challenge, which it is sponsoring. For a limited time, WIZnet is offering discounted WIZ550io Ethernet controller modules and W5500 chips via its webshopWiznet-Challenge-EELive

Disclosure: Elektor International Media and Circuit Cellar comprise the challenge administration team.

At this time, WIZnet’s WIZ550io is on sale for $9.95 (original price, $17.00) and the W550 cost $1.49 (original price, $2.87).

WIZnet’s WIZ550io is a module for rapidly developing ’Net-enabled systems. It is an auto-configurable Ethernet controller module that includes the W5500 (TCP/IP-hard-wired chip and PHY embedded), a transformer, and an RJ-45 connector. The module has a unique, embedded real MAC address and auto network configuration capability.

WIZnet's WIZ550io auto configurable Ethernet controller module includes a W5500, transformer, & RJ-45.

WIZnet’s WIZ550io auto configurable Ethernet controller module includes a W5500, transformer, & RJ-45.

The W5500 is a hardwired TCP/IP embedded Ethernet controller that enables Internet connection for embedded systems using Serial Peripheral Interface (SPI).

W5500

W5500

Visit the WIZnet Connect the Magic 2014 Design Challenge webpage for more information about participation and eligibility.

IR Remote Control Testing (EE Tip #119)

On the Internet you can find them in all shapes and sizes: circuits to test remote controls. Here I describe a simple and cheap method that is not that well-known.

This method is based on the principle that an LED does not only generate light when you apply a voltage to it, but also works in the opposite direction to generate a voltage when light falls on it. Within constraints it can therefore be used as an alternative for a proper phototransistor or photodiode. The major advantage is that you will usually have an LED around somewhere, which may not be true for a photodiode.

IR remote tester

IR remote tester

This is also true for infrared (IR) diodes and this makes them eminently suitable for testing a remote control. You only need to connect a voltmeter to the IR diode and the remote control tester is finished. Set the multimeter so it measures DC voltage and turn it on. Hold the remote control close to the IR diode and push any button. If the remote control is working then the voltage shown on the display will quickly rise. When you release the button the voltage will drop again.

However, don’t expect a very high voltage from the IR diode! The voltage generated by the diode will only be about 300 mV, but this is sufficient to show whether the remote control is working or not. There are quite a few other objects that emit IR radiation. So, first note the voltage indicated by the voltmeter before pushing any of the buttons on the remote control and use this as a reference value. Also, don’t do this test in a well lit room or a room with the sun shining in, because there is the chance that there is too much IR radiation present.

To quickly reduce the diode voltage to zero before doing the next measurement you can short-circuit the pins of the diode briefly. This will not damage the diode.—Tom van Steenkiste, Elektor, 11/2010

Want tips about testing power supplies? We’ve got you covered! EE Tip #112 will help you determine the stability of your lab or bench-top supply!

Arduino-Based DIY Voltage Booster (EE Tip #117)

If your project needs a higher voltage rail than is already available in the circuit, you can use an off-the-shelf step-up device. But when you want a variable output voltage, it’s less easy to find a ready-made IC. However, it’s not complicated to build such a circuit yourself, especially if you have a microcontroller board that’s as easy to program as an Arduino. And this also lets you experiment with the circuit so you can get a better understanding of how it works.

Source: Elektor, April 2010

Source: Elektor, April 2010

No surprises in the circuit—a largely conventional boost converter. The MOSFET is driven by a pulse width modulated (PWM) signal from the microcontroller, and the output voltage is measured by one of the microcontroller’s analog inputs. The driver adjusts the PWM signal according to the difference between the output voltage measured and the voltage wanted.

We don’t have enough space here to go into details about how this circuit works, but it’s worth mentioning a few points of special interest.

The small capacitor across the diode improves the efficiency of the circuit. The load is represented by R3. The components used make it possible to supply over 1 A (current limited by the MSS1260T 683MLB inductor from Coilcraft), but maximum efficiency (89%) is at around 95 mA (at an output voltage of 10 V). To avoid damaging the controller’s analog input (≤5 V), the output voltage may not exceed 24 V. For higher voltages, the values of resistors R1 and R2 would need to be changed.

The MOSFET is driven by the microcontroller, which is nothing but a little Arduino board. The Arduino’s default PWM signal frequency is around 500 Hz—too low for this application, which needs a frequency at least 100 times higher. So we can’t use the PWM functions offered by Arduino. But that’s no problem, as the Arduino can also be programmed in assembler, allowing a maximum frequency of 62.5 kHz (the microcontroller runs at 16 MHz). To sample the output voltage, a frequency of 100 Hz is acceptable, which means we can use Arduino’s standard timers and analog functions. The Arduino serial port is very handy: we can use it for sending the output voltage set point (5–24 V) and for collecting certain information about the operation. Thanks to the Arduino environment, it only took about half an hour to program. Software is available. — Clemens Valens (Elektor, April 2010)

PCB Design Guidelines (EE Tips #113)

Designing a matching printed circuit board (PCB) can be a challenge for many electronics enthusiasts. To help ease the process, Circuit Cellar and Elektor editors compiled a list of tips for laying out components, routing, and more.PCB1

  • When compactness is not a major consideration and the boards will be assembled by hand, through-hole components are the better choice. In this case you can use the pins of these components as “vias.”
  • On the other hand, surface-mount components can save a whole load of drilling on self-made PCBs. They make it simpler to achieve objectives such as minimum length for traces , minimal area inside trace loops, etc.
  • The orientation of components should consider not only simplicity of assembly but also the need to test the circuitry afterward. This is the time to remember the need for test points!
  • The place for switches, press buttons, plug-in connectors, LEDs and other user-interface components is outside the enclosure. Anything requiring subsequent access should be on the front panel of the case.
  • Components that require assembling with the right polarity should all have the same orientation.
  • Manual routing is preferable to using the autorouter. The latter has its uses nevertheless for discovering bottlenecks and other critical points.
  • When routing, never even think about giving up! Many PCBs appear “unroutable” at the outset, yet after a while it turns out you have plenty of space to spare.
  • If you’re not satisfied with your efforts, it’s better to go back a step or two rather than just muddle onwards.
  • Complete the routing for each of the functional groups of the circuit first. Link the groups together only after you have finished this stage.
  • Short traces are better than long ones. High impedance connections are more sensitive to interference and for this reason require to be kept as short as possible.
  • Where traces form a loop, their surface area should be kept to an absolute minimum.
  • Decoupling capacitors must be located as close as possible to the switching element that needs to be decoupled.
  • Traces carrying signals should be routed early on (first the short ones, then the long ones). Except, that is, when the power supply traces are particularly critical.
  • Bus lines should be routed alongside one another.
  • Separate analog circuitry from digital whenever possible.PCB2
  • On multilayer boards arrange traces carrying signals so that one of the layers hosts the vertical traces and another one accommodates the horizontal ones.
  • If possible, reserve one layer or side exclusively for a continuous ground plane. Only in exceptional situations, e.g. with high speed op-amps, is this undesirable.
  • Keep traces carrying heavy currents well away from sensitive pickups, sensors and so on.
  • Beginners should take special care with mains and high voltages!
  • Ground and earth traces require exactly the same consideration as the power supply traces. Electromagnetic interference can be minimized by keeping the power and ground traces parallel (or better still arranged over each other on either side of a double-sided board).
  • Bends should be no more than 45°. Sharp angles between the traces and the pads are also to be avoided.
  • Observe PCB manufacturers’ requirements without exception in order to avoid unpleasant surprises later.
  • If you are using software for checking conformity to specifications, carry out these checks regularly at each design phase.
  • A border of 0.12″ (approximately 3 mm) around the edge of the PCB should be kept entirely clear of components.
  • If components are to be inserted by machine you must provide at least three location marks.
  • Don’t forget the holes for fixing screws or pillars!
  • Don’t skimp on text markings on the PCB: indicate polarity, voltages, on-board functions, part designation, design date, version number…
  • Check not just twice but three times that all components will actually fit the PCB!
  • Leave time at the end of the process for tidying up and optimizing.

Good luck!