Dave comments on the Sparkfun/Fluke multimeter customs trademark/trade dress fiasco, and shows off the new low cost Fluke 114/117 Kit Multimeter about to be released.
EEVblog #597 – Fluke 114 Kit Multimeter + Sparkfun/Fluke Rant - [Link]
A multimeter is an essential piece of kit for anyone who works with electronics. Combining the functions of a voltmeter, ammeter and ohmmeter — hence the prefix ‘multi’ — these tools are the fastest, safest and most effective way of diagnosing a problem in an electrical circuit.
And while it’s important that who anyone doesn’t own one of those tools does their utmost to get their hands on one, it’s worth taking into consideration a few issues before you commit to a purchase.
This post tells you everything you need to know about buying a multimeter of your own, to ensure that the latest addition to your equipment is to up the job at hand.
Analogue or digital?
Like all equipment, multimeters have seen their fair share of improvements over time and the introduction of digital displays is one way multimeters have become more reliable and easier to use.
What effect does your multimeter input impedance have on the circuit you are measuring? Dave shows a practical example of how it can really screw things up if you aren’t watching out for it.
EEVblog #584 – What Effect Does Your Multimeter Input Impedance Have? - [Link]
Mooshimeter: The Wireless Graphing Multimeter with Data Logging and Multichannel Simultaneous Sampling
The Mooshimeter makes multi-channel measurements possible in situations that are too fast, too slow, too sensitive, or too dangerous to use a traditional multimeter. And by harnessing your smartphone’s hardware, it does so at an insanely low price.
The Mooshimeter was born out of our frustrations as electrical engineers at the limitations of the “standard” digital multimeter.
Almost every digital multimeter will only let you use one mode at a time, meaning that to watch relationships in an active system you need to use multiple meters. Most have a front panel dominated by a numeric LCD display and a gigantic mode selection knob. And having the display mounted on the measurement hardware makes it very difficult to measure moving or enclosed systems, because the user must have clear line of sight to the meter to be able to read it.
Mooshimeter – Measure 600V and 10A with 24 bit precision through 50 meters - [Link]
Universal multimeter UT139C with a high resolution will be appreciated at development and everywhere, where you need to find out a situation in a given device accurately
Imagine a situation, when you need to check or set a voltage of 3.3V or 5V usual at digital electronics (AD converters reference,…). Or to measure the end of recharging of Li-ion/ Li-Pol batteries at 4.20V when it really matters on every miliVolt. In these cases, with usual multimeters you´ll face one cardinal fact – regarding that the most of them has a max. display reading of 1999, you´ll measure in hardly the first quarter of a range, thus with a significantly lower resolution. For example instead of desired 4.001 V (3 decimal positions), you´ll only see 4.00V. Naturally, we don´t always need such a high resolution but many times an improvement of resolution in one magnitude can provide us a worth information about a real situation in a measured circuit. In these situations it often doesn´t matter on the absolute accuracy that much, but right on a resolution, especially when comparing voltages in two points, increase/ decrease…
From this point of view is the novelty in our stock UT139C an excellent device providing besides a high resolution (5999) also another features worth to notice, for example: TRUE RMS measurement in a range of 45Hz-1kHz (to 400 Hz with VFC filter activated), measuring of high-capacity capacitors up to 99.9 mF (99 999 uF), measuring of duty cycle in a range of 0.1% – 99.9% and other. Not quite common is also measuring of uA and mA even in AC range. Function Rel is useful even at measuring of small capacitors, where it´s able to eliminate “offset” caused by a capacitance of testing leads.
A thermometer (K type) with arrange of -40 to 1000°C can also be useful at development. From some point of view it´s advantageous supplying by two AA cells, not by a classic 9V battery (AA cells have a better capacity/ price ratio).
UT139C is also able to serve as a non-contact AC voltage tester (NCV), indicating in 4 steps a proximity of >100VAC voltage. . Indication is by a red LED in the upper part of display, by a display (-,–,—,—-) and by a buzzer.
Further information will provide you the UT139C datasheet.
With the UT139C you´ll find out why 5999 is better than 1999 - [Link]
Inrush current, effective power, power factor, harmonic distortion, … all these and other parameters handles CM8 with easiness.
Clamp multimeters are often used mainly thanks to their ability to measure AC (and even DC) current even without a disconnection of a wire. But it´s only one basic feature, which more sophisticated devices can use even for another purposes, like comfortable measuring of power and power factor. Benning CM8 is a device able to provide detailed information regarding power conditions in a measured circuit and measure much more than usual clamp meters, for example:
● measuring of inrush current
● measuring of effective power in 4 ranges – 4/40/400/600 kW + calculation of a power factor in a full range -1,00…0…+1,00
● VAC true RMS in a frequency range of 45-500Hz, high accuracy up to a crest factor of 3
● harmonic distortion with 0,1% resolution and sensitivity up to 25-th harmonic (ACV, ACA)
● measuring of DC current up to 600A (0.1A resolution)
It can be said, that Benning CM8 is a device, with which it´s possible to check even large circuits and for example find possible source of defects and similar. Thanks to a measurement of inrush current it´s able to give a real information about a load of a circuit and thus for example to give an information, whether it´s possible to add another device into a given circuit etc.
Detailed information about the CM8 will give you the Benning CM8 user guide and an overview of Benning measuring and testing devices.
Top class multimeter Benning CM8 examines even motors - [Link]
A multimeter is a brilliant instrument that combines several functions – typically, measuring voltage, current and resistance. Although both digital and analogue multimeters exist, the vast majority in use today are digital and hence this guide will use images of a digital multimeter, or DMM, to illustrate various steps.
How to Use a Multimeter - [Link]
Multimeter VA588 also measures an insulation resistance at voltages of 50-1000V thus enabling to check many devices or an electric installation.
A possibility to measure an insulation resistance of various devices is very useful and it is often able to discover a beginning problem on time – sooner, than it will appear in a form of a device malfunction or an injury. Though VA588 doesn´t replace an expensive professional revisional instrument but it is able to reliably discover a diminished insulation and significantly increase safety of your workplace.
VA588 literally represents a 2in1 solution. Besides an insulation tester with a selectable testing voltage of 50-100-500-1000V, you also gain a solid automatic range multimeter with max. 5000 counts. As an insulation resistance in the most of cases doesn´t have a linear character, the measurement at a higher voltage is much closer to reality than measurement with a common multimeter with a testing voltage of 0,5-3V. In other words, VA588 creates a testing voltage by a built-in DC/DC module and from the current flowing through a testing circuit it calculates an insulation resistance value.
VA588 also features further useful features like True RMS measuring, measurement of AC current with 0,1uA resolution, 51-segment analog bargraph and measuring of frequency of linear as well as digital signals. Also beneficial is the possibility to activate/ deactivate an auto-off function.
Test the safety of your devices with the VA588 multimeter - [Link]
A modular system of laboratory devices Hameg 8000 series is an ideal system for testing workplaces and school laboratories. At the same time it enables a very effective usage of space.
To have all we need on a table and to maintain enough space for a work – it is a stable challenge at a work with electronics. We may say, that for example a generator won´t be on my table today. But as it uses to be, after a while we´ll find we need just that instrument, which is missing on a table. Sometimes a solution is to stock them at each other, but we usually face the problem with a different size of instruments, or eventually also an instability of such a “set”. All this is solved by a Hameg 8000 series modular system.
The system consists of a HM8001-2, main unit, serving as a power supply and at the same time it is a holder – frame for any 2 instruments from the 8000 series (instruments don´t have their own power supply – for their operation they need to be inserted into the HM8001-2 basic module). Up to 5 such mainframes can be stocked at each other, what means up to 10 instruments. That brings a big saving of space and especially a comprendious and safe work. At the same time, it enables a big variability – for example usually a one mainframe + 2 instruments (according to an actual need of a given lesson) are usually sufficient for students in school.
- HM8012 – 4¾-Digit Programmable Multimeter (max value 49999) with 0.05% basic accuracy, max. resolution: 10μV, 0.01dBm, 10nA, 10mΩ, 0.1°C, offset function and a relative value measurement, including an RS232 interface and software
- HM8018 – 25kHz LCR-Meter, measures L, C, R, Θ, Q/D, |Z|, 0.2% basic accuracy, 5 measuring frequencies (100Hz, 120Hz, 1kHz, 10kHz, 25kHz), max resolution: 0.001Ω, 0.001pF, 0.01μH, 2- and 4-wire measurement, parallel and serial mode
- HM8021-4 – 1.6 GHz Universal Counter, measurement range 0Hz…1.6GHz, 10MHz time base with 1ppm stability, 2 inputs – 1MΩ/ 50Ω
- HM8030-6 – 10 MHz Function Generator, frequency range 50mHz…10MHz, output voltage up to 10Vpp (do 50Ω), waveforms: sine wave, triangle, square wave, pulse, DC, distortion <0.5% up to 1MHz, rise and fall time 15ns typically, internal and external sweep, FM (with option HO801), surge- and short-circuit-proof (ideal for testing and educational conditions)
- HM8040-3 – Tripple Power Supply Unit 2x 0–20V/0.5A – 1x 5V/1A, 3-digit switchable displays (resolution 0.1V/1mA) , Pushbutton for activating/deactivating all outputs, adjustable current limiting and electronic fuse, low residual ripple and low noise
- HM800 – Blank Module intended for customized instrument construction, inner guide for PCB mounting in 4 various levels, plastic front panel for easy mechanical processing, power is supplied by the HM8001-2 mainframe
As can be seen from this description, those are the quality instruments with very decent specification and with an excellent price/ performance ratio. Excellent properties are mainly proven in praxis, in a form of several 100 000 units sold all over the world. Detailed information will provide you datasheets at particular modules, series 8000 overview and the overview of options. In case of interest in any Hameg or Rohde&Schwarz instrument, please contact us at firstname.lastname@example.org
With the Hameg 8000 series devices you always have on a table all you need - [Link]
I watched EEVblog’s video about debugging a short circuit with precise multimeter. He determined the direction of shorted place by comparing resistances in different places. I wanted to debug like that too and also measure resistances of wires and connectors, but all cheap multimeters measure only down to 0.1Ω. To get 10mΩ I have to buy 400€ multimeter. So I searched and found an article describing cheap and dirty way to measure low resistances. You need a known voltage source and known resistors and then you can form a voltage divider and measure the resistance. Awesome! But the form factor and all the math behind it sucks, as a plug and play device it would be perfect. I though about making it its own box, but was almost impossible to find cheap probe connectors for panel or PCB. So it will be a one PCB product.
First, the concept.
- It should measure resistances from 1Ω to 0.1mΩ
- General purpose – can be plugged in any multimeter.
- Output should be in mV, because most multimeters have mV display.
- No math, so 1mΩ is translated to 1mV and user doesn’t have to calculate anything.
- Precise enough – 1% is nice number, but it’s not very important, as usually we need the resolution, not the absolute precision.
Half Ohm – milliohm multimeter adapter - [Link]