Anyone who deals with electronics for professional or private reasons will quickly find that the kitchen table at home or a standard office workplace are not suitable places for working with electronic devices. In addition to the actual circuit, various tools and measuring devices have to be set up and operated. A fixed workplace with permanently installed measuring devices is more practical and safer for this work.
But what belongs in such a workplace? How do I choose the right devices? How do I set up the workplace? These questions are answered in the following article.
Electric security
“Safety first” is the top priority when dealing with electricity. When setting up an electronics workstation, this means that the electrical installation must comply with the valid German installation regulations. A 10mA RCD (Residual Current Device) is an absolute must.
Particular importance must be attached to standard-compliant earthing (PE). This is important in two ways. Firstly, the life and limb of the electronics technician is at stake and secondly, good grounding is essential to keep electrostatic charges away from the sensitive electronic components.
Industrial electronics laboratories have their own grounding networks for ESD protection, because the protective conductor is an essential factor for safety in industrial companies and is literally always live. This is mainly caused by frequency converters and switched-mode power supplies, which allow their leakage currents to flow out of the EMC filters via the protective conductor.
Here is a practical example from everyday work: In a data center (approx. 800 servers) I measured over 30A leakage current when checking the electrical installation. If you connect an electronics workstation to such a protective conductor, personal protection is not endangered, but all ESD measures are no longer necessary.
Workplace furnishings (table, sockets, etc.)
First and foremost, a workplace means a table. This should make it possible to work in a relaxed and fatigue-free manner. The table surface should be 90×200 cm so that the measuring devices fit on it and there is still enough room to move around to work. Storage space in the form of drawers is also necessary.
Ideally, the measuring devices are on a shelf above the work surface. This shelf must be firmly attached to the table. In the private environment, the table will certainly be made entirely of wood. For the ESD protection measures, this means that additional components are required, more on this later.
In the professional environment you will find tables that stand on a metal frame and whose worktop is made of wood. This wood is then laminated with a copper foil. The metal construction of the table is connected directly to the protective conductor or the separate ESD network, as is the metalized work surface. When it comes to particularly sensitive electronic components, even the paint on the metal construction is electrically conductive. To do this, graphite is added to the powder coatings in order to obtain a conductive surface during powder coating.
A little excursion into the past: My first workplace in the 1970s in an electronics laboratory (BASF magnetic technology laboratory) was reinforced with a 120 mm I-beam. On it stood measuring devices in sheet steel housings, each weighing between 50 and 100 kg. The manufacturer of the measuring devices was nicknamed by me and my colleagues: “Rusty & Heavy”, derived from the company logo. The older readers will know which company I mean. Because they still exist today. We have it much easier these days in the truest sense of the word.
There should be a sufficiently large number of sockets at the table, all of which can be switched off using an emergency stop switch. Ideally, the sockets are in a cable duct that is permanently connected to the workplace. Multiple sockets are an absolute “no go”, even in the private sphere.
Analog versus digital
In the past, everything you could buy in terms of measuring devices was analogue. So the question did not arise: Do I use an analogue measuring instrument or a digital measuring instrument? Digital measuring instruments are always justified when it comes to precise measurement of values. Analogue measuring instruments are superior to digital ones, for example when it comes to calibration work. The “fidgeting” of a digital display can be quite annoying when comparing, because it is difficult to recognize a trend: Is the value going up or down? An analog pointer instrument is much easier to read. The movement of a pointer is easier for the human eye to detect than constantly changing digital values. In the description of the devices I go into more detail on the topic.
What belongs on the work table
I want to answer the above question first with a list of devices. In my opinion, the devices listed below belong on a normally equipped electronics workstation.
Device list
- Oscilloscope
- Laboratory power supply
- Function generator
- Multimeters
- Component tester for semiconductors
- LCR meter
- Control isolating transformer
- Soldering station
- ESD work mat
- ESD tool kit
Special devices such as a spectrum analyzer or an EMC measuring device are not necessary for normal daily use.
Which device can do what? Which criteria help to find the right device?
The device list is quite long and finding the right devices for your own workplace is not easy. For an initial orientation, there are three criteria that should be clarified:
- Technical requirements resulting from the task
- Budget
- Space conditions
These three criteria provide a rough framework. In order to select and buy the most suitable device for one’s own use, a device-specific consideration is required. That’s why I’m going to take a close look at device by device and provide decision-making aids.
Digital storage oscilloscope
The first oscilloscope-like devices appeared in the 1930s. They were not calibrated and were mostly used to display voltage curves. They were mainly used in the emerging radar technology. The first oscilloscope similar to those in use today was released by Tektronix in 1946. It was christened “Model 511”.
What are the criteria for choosing an oscilloscope?- Bandwidth or the largest possible frequency that can still be displayed
- CAT category: I, II, III or IV
- Number of required measurement channels
- Included supply
First you have to be clear about the frequency range in which you want to work with the oscilloscope. It makes sense to start with a bandwidth of 20 MHz. You shouldn’t go below that. There are devices in the professional class today that go far beyond 1 GHz. Lower bandwidths are not useful and usually result in inaccurate and poor measurement results. PC sound card solutions or the µController-based solutions are mostly useless for daily use.
In the case of digital oscilloscopes, the sampling rate is an additional quality criterion. The higher this is, the more accurate the digital measurement result is. The sampling frequency should be at least 5 times higher (Nyquist criterion) than the bandwidth of the device. In contrast to analogue devices, which display a signal continuously, it can happen with a digital oscilloscope that fast signals that occur during the sampling pauses are not recorded at all. This is a big problem, especially with inexpensive devices with a low sample rate. Here it can happen that a signal cannot be measured even though it is present.
CAT measurement categories
Another important point is the classification and approval of the oscilloscope according to the CAT measurement categories. These categories determine the environment in which a measuring device may be used. There are four of them, which also apply to all other measuring devices:
CAT I: Measurements on circuits that have no direct connection to the mains (battery operation), e.g. devices of protection class 3 (operation with safety extra-low voltage), battery-operated devices, conventional car electronics.
CAT II: Measurements on circuits that have a direct connection to the low-voltage network by means of a plug, e.g. B. Household appliances, portable electrical appliances.
CAT III: Measurements within the building installation (stationary loads with non-pluggable connection, distributor connection, permanently installed devices in the distributor), e.g. sub-distribution.
CAT IV: Measurements at the source of the low-voltage installation (meter, main connection, primary overcurrent protection), e.g. meter, low-voltage overhead line, service connection box.
(Source: https://de.wikipedia.org/wiki/Messkategorie)
Good oscilloscopes have at least CAT II with an upper limit voltage of 300 V or higher. An oscilloscope should have at least two input amplifiers and be able to display two signals at the same time. Professional-class devices have up to four channels that can be displayed simultaneously. The probes for the input channels must match the measurement category of the oscilloscope. Since the probes usually come with the oscilloscope, this is usually the case. Nevertheless, you should always be careful and look closely.One safety note: Never use an oscilloscope to measure directly on the mains voltage if the device is not connected to an isolating transformer. This destroys the oscilloscope and puts the technician’s life in danger.
Product Recommendations:
Digital: RTB 24-70
Laboratory power supply
Today, laboratory power supplies can be divided into two technology classes:
- Classic longitudinally controlled devices
- Switched devices with flyback converters
The clocked devices do not get as warm and they are available with higher output currents, which is an advantage when dealing with power electronics circuits. Today, two-channel versions of these devices are the standard. These devices are also suitable for parallel connection or series connection. Only the quality of the output voltage is not as good as that of the linearly regulated devices.
The output voltage range of the standard devices is usually from 0-30 V. This is sufficient for normal laboratory work. If higher voltages are required, special devices must be used.
Another important function is the adjustable output current. Good laboratory power supplies can also be used as a constant current source.
If you work a lot with amplifiers and audio and video electronics, a longitudinally regulated laboratory power supply is preferable to the clocked version. If you need a lot of power, the clocked version is the right choice. After some time, both variants will probably be on the measuring device shelf.
Product Recommendations:
Klein, kompakt: PEAKTECH 6226
Groß, mehrere Kanäle: GPP-4323
Function generator
Sine, square, triangle – these are the signal forms that you deal with in everyday laboratory work. In the past, these signals were generated in analog form, but today they are handled by digital signal processors in so-called DDS signal generators. The quality of the generated signals is excellent and puts the analogue predecessors out of work.
There are also upper bandwidth limits for the function generators. Devices capable of generating signals up to 5MHz is a good standard. But here, just like with oscilloscopes, the higher the better.Even simple DDS generators can now do more than their analogue predecessors.
- Standard AM
- FM
- PM
- FSK
- SUM
- Sweep
- Burst and frequency counters
It doesn’t have to be two channels, but if the device has them, it’s not a disadvantage. In terms of quality, standalone DDS generators are consistently good. PC solutions, on the other hand, are not recommended.
Product Recommendations:
JOY-IT PSG9080
Multimeter analog and digital
Actually, the question of “analogue or digital” does not arise here. You need both types of devices on the laboratory bench. Digital multimeters are indispensable because of the accuracy of reading and analog multimeters because of their pointer, which is superior to the digital display when adjusting filters and other circuits. The bar graph displays of some digital multimeters are not a suitable substitute for a measuring pointer.The measurement category is important when selecting the multimeter. CAT III and a maximum of 600 V measuring voltage are the lowest limit. Anything below that is not suitable for the laboratory workplace.
A mirror scale is now standard on analog multimeters to improve reading accuracy. You shouldn’t use anything else. The number of digits displayed is important for digital multimeters. There should be at least four, the more the better, but also more expensive.
Product Recommendations:
Analog: PEAKTECH 3201
Digital: FLUKE 179
Component tester for semiconductors
If you are repairing electronic devices or you have to select components, a tester specializing in semiconductors is essential.
The “Tektronix Curve Tracer 576” and its successors were legendary in this category of measuring devices. The 31kg colossus was able to measure everything that was available at the time in terms of components. He was even able to draw a family of curves on the oscilloscope screen. Working devices are still traded in the four-digit range today. Current component testers are much smaller and handier.You can measure some things with the multimeter, but if you have to measure a MOSFET transistor, for example, this is no longer feasible with the multimeter. In addition to the information that the component is working, the component testers specializing in semiconductors also provide information about which component it is and what its key figures are. If you have to select components with the same key figures, for example, this cannot be done without a component tester.
Produkt-Empfehlung:
JOY-IT LCR-T7
LCR meter
L=inductance (coils), C=capacitance (capacitor), R=resistance. An LCR meter is an indispensable tool to check these passive components. For this task, a multimeter should be regarded more as a “tap”. An LCR meter is superior to a multimeter in terms of precision and accuracy. In addition, good LCR meters can provide additional information about the component to be measured. In the case of capacitors, for example, they provide information about the important ESR value or, in the case of coils, about their quality. Since the demands on accuracy are very high, the LCR meter is the most expensive measuring device on the laboratory bench after the oscilloscope.
Product Recommendations:
Tabletop device:: LCR-6002
Portabel: PEAKTECH 2170
Control isolating transformer
The control isolating transformer is used when a device is to be switched on for the first time or if there is a defect. With the isolating transformer, a device can be carefully energized without it immediately smoking.
The galvanic isolation from the mains makes it possible to work safely on a device that is live with mains voltage. What is striking about these devices is the Schuko socket without protective earth contact. This is necessary so that there is 100% galvanic isolation. The output of a control isolating transformer must not be grounded. Also, no further protective measures such as RCD (FI) may be connected downstream. They would not work and violate the DIN regulation that no second protective measure may be connected to a control isolating transformer.A control isolating transformer should have an output of approx. 1 kW. This is sufficient for everyday laboratory work. A meter for voltage and current should also be installed.
The control isolating transformer will be the heaviest part on the laboratory bench and should be placed on the bench so that it is easily accessible. For safety reasons, storing it in a rack or on a shelf is not recommended.
Product Recommendations:
PEAKTECH 2235
Soldering station
Since July 2006, only lead-free solder may be used in the EU. The lead-free replacement solders place increased demands on the soldering stations. The days of unregulated soldering irons with outputs below 50 W at the electronics workstation are over. Higher temperatures must be maintained more precisely in order to obtain a functioning soldered connection. Above all, this requires higher electrical power in the soldering iron. 80 W-150 W are necessary today to reach and maintain the working temperatures for the soldered joint. Electronic control is required to precisely maintain the soldering temperature. These requirements are easily met by modern soldering stations.
Product Recommendations:
WELLER WT1010H
ESD protection
There was a time in the history of electronics when ESD protection was not an issue. ESD means Electro Static Discharge. Tubes, relays or mechanical selector switches were absolutely insensitive to electrostatic discharges. With the advent of semiconductors in the 1950s, the topic became increasingly important. Today, ESD protection is mandatory at every electronic work station. Working on electronic assemblies without effective protective measures against “ESD lightning” is grossly negligent. Fortunately, this was quickly recognized and products were brought onto the market that provide effective help against electrostatic discharges.
ESD work mat
If you work on assemblies that are ESD-sensitive in an environment that is not set up for such work, you can use an ESD work mat. Such a mat is connected to a Schuko socket with a special plug to ensure safe contact with the protective conductor. The electrostatic discharges are discharged via this connection. The second important utensil is a wristband for the technician, which is connected to the work mat with a snap fastener. There is a resistor in the supply line with less than 1Mohm for personal protection. Equipped in this way, it is no problem to work on ESD-sensitive assemblies.In addition to this work mat, there are other accessories for an ESD-safe workplace. This is particularly important for industrial use.
Product Recommendations:
BERN 9 354 100
The range of ESD grounding material is relatively comprehensive.
ESD tool kit
The right tool is also part of an ESD-protected workplace. Otherwise all the expensive ESD protection measures are useless. The tool that is used in such a workplace must also guarantee ESD protection. It is an important link in the ESD protection chain.
Product Recommendations:
WERA 05134019001
KN 00 20 18 ESD
Summary
This was my advice on the subject of electronic work stations. One last tip at the end: If an electronics workstation is set up, you invest a large sum of money – whether privately or professionally. In addition to quality and precision, you should definitely make sure that there is a local repair and calibration service for the expensive equipment. With regular maintenance and care of the devices, you can enjoy them for a long time.
Images: Adobe Stock
