Bench Talk

The rise of Open Source Hardware (OSHW) has made it easier than ever to tinker with electronics. But even in a world where open source development (dev) platforms are making it appreciably easier to get started, tools are still a must for doing any serious circuit building and testing. Investing in good tools early in your maker career can make all the difference as to whether or not you stick with electronics as a hobby (or even profession), or give up in frustration when a circuit doesn’t quite work the way you intended.

Just as there are seemingly endless options of open source hardware platforms, there are tons of options and configurations of tools as well. Unless you were a recent lottery winner, chances are your resources aren’t unlimited. Knowing which tools to invest in early and which can wait for later in a career is perhaps a matter of opinion depending on your specific project goals. However, there are a couple tools that many would agree are smart to invest in early on. Spending a few extra bucks on quality tools today can save hours (and potentially even more money) in the future.

Here is a look at some of the tools we recommend you consider:

1. Digital Multimeter (DMM) - A digital multimeter is the fundamental tool for understanding what is happening in your circuit. Beyond the three basic measurements of voltage, current, and resistance, a decent low-cost DMM today will also measure characteristics such as signal frequency and duty cycle. Even $30 can get you a DMM that includes the ability to measure capacitance and temperature (via an included thermocouple probe). While lower cost options might trade off accuracy, ruggedness, or other advanced features, for a lower price, a reasonably priced DMM is a wise first investment when building your electronics toolbox. The Extech MN15A is a pretty solid choice for first DMM that includes a thermocouple for measuring temperature and has the ability to measure capacitance. For the various budget-conscious, check out the Gravitech DMM-899 it’s barebones current, voltage and resistance measurements but it’s also very inexpensive.

Figure 1: Weller WESD51 digital 50W soldering station. Microprocessor controlled with LED digital display in F/C.

2. Variable Temperature Soldering Station - When you are ready to go from breadboard only projects to something more permanent, you will need to start learning how to solder. Soldering is sort of like that mythical “weed out” course in college, the one that separates those who like the idea of majoring in a certain subject from those who are actually crazy enough to stick with it until graduation. The skill of soldering is not especially hard. However, if your first experience is bad one as a result of using a cheap soldering iron with poor temperature controls, it can be enough to forsake electronics forever. A good soldering iron is one that has good variable temperature control and an assortment of easily interchangeable soldering tips. A brass sponge is also highly recommended.

A solid choice is the Apex Tool Group’s WESD51 digital soldering station which will give you 350°F to 850°F of finely controlled temperature depending on what components you are soldering.

Figure 2: A decade box is invariably useful for testing out resistor values in a prototype without having to swap out resistors manually. Image courtesy Global Specialties. 

3. Resistor Substitution Box - This is one of those tools that you may not use every single day but is invariably useful for just about every project I have ever worked on. A resistor substitution box is a simple but clever device that lets you very easily test out a variety of resistors in a prototype without having to constantly swap out resistors manually. Simply insert the leads of the substitution box into the part of the circuit where you will eventually place the leads of a fixed resistor. Then by turning the knobs on the substitution box you can quickly step through a variety of resistance and monitor how the circuit reacts. This is extremely useful in a voltage divider circuit in which one of the resistors is variable, for example, a photoresistor. If you have a desired quiescent output voltage when the circuit is in ambient conditions, you can use the resistor substitution box to determine the ideal value for the fixed resistor. Then in your final circuit you will replace the substitution box with a fixed resistor of the appropriate value. There are also capacitance substitution boxes that perform a similar role for capacitors.

There are quite a few good options of substitution boxes at a a reasonable cost including the Global Specialties’ RDB-10 and the Extech 380400. Both allow you to dial-in a variety of resistances from the single ohms all the way up to multiple mega-ohms.

4. Bench Top DC Power Supply - Battery packs, wall warts, and USB cables are all ways we’ve powered our circuits at one time or another. Eventually, the mess of having to accumulate a massive collection of wall warts of various voltage and current ratings can get old. A reliable benchtop DC power supply is a welcomed addition to just about any electronics workspace. I prefer a split voltage power supply that can produce both positive and negative voltages, useful for many operational amplifiers applications. 0V to 30V at 1A is a respectable power supply for most DIY applications.

Take a look at the B&K Precision 9110 benchtop supply which will provide up to 60VDC and 100W in a very small form factor. If your application requires a little more control over characteristics such as inrush current or you wish to mimic battery performance, check out the Keithley 2260B power supplies that have USB connectivity so you can control the power output from a desktop computer.