Secret world of oscilloscope probles article written by Doug Ford and published by Silicon Chip magazine, describes how high frequency oscilloscope probes really work. Most textbooks treat scope probes as a combination of a resistive divider in combination with capacitors to provide an extended frequency response. But as will be revealed, the reality is that they are much more complex in principle. The hidden secret to designing a good 10x oscilloscope probe seems to be to use lossy transmission line cable! Usually the coax cable on probles has been made deliberately lossy, to reduce the effects of end-to-end transmission-line reflections!
62 Comments
Tomi Engdahl says:
Scope bandwidth, rise time, and the “rule of five”
http://www.edn.com/electronics-blogs/other/4391632/Scope-bandwidth–rise-time–and-the–rule-of-five-?cid=EDNToday
You might easily think that a 500-MHz oscilloscope would be good for measuring sine waves up to 500 MHz. As I noted in an earlier post, however, this isn’t the case. There are at least two approaches you can take to make sure get the right scope bandwidth for your application.
First, if you have a maximum sinusoidal frequency in mind, you can work with the bandwidth specification of the scope. However, you’ll need to account for the roll-off of the scope.
Second, if you’re looking at non-sinusoidal signals, such as digital pulses, the highest frequency in your signals will be a multiple of the highest repetition rate. You’ll need to use a scope bandwidth much more than five times the repetition rate to account for harmonics. If you’re working on digital systems, it’s often easier to consider the rise-time specifications for scopes.
Tomi Engdahl says:
Make Your Own Probes
http://www.scopejunction.com/author.asp?section_id=1835&doc_id=253846&cid=reg-email-12-18
You may never have thought to make your own scope probes, but sometimes, they’re just what the doctor ordered.
The first inkling I might want to make my own probes came when I was pondering how to use the 50Ω inputs on some of my scope modules for general probing, as opposed to a direct connection to a 50Ω source. OK, so, maybe I haven’t built mine yet, but let’s consider the options when it comes to rolling your own.
Glen created 500Ω 10:1 probes by soldering 50Ω coax to a 450Ω (453Ω is a standard value) resistor, which is soldered to the circuit under test. The scope is set to 50Ω input mode, of course.
SJ user clockman (Hugh Houtman) has also mentioned some homemade probes, which I’ve further discussed with him. Hugh’s goal was to achieve fast risetime along with extremely low capacitive loading, so his 100:1 probe consists of 100MΩ of series tip resistance paralleled with 1pF, driving his scope’s 1MΩ input.
Because of the impedance mismatch between the coax cable and the scope’s input, there are some reflections,
Tomi Engdahl says:
Oscilloscope probes: Understand and optimize
http://www.edn.com/design/test-and-measurement/4420010/Oscilloscope-probes–Understand-and-optimize
Editor’s Note: This article is a guide to predicting the performance of your probe for your specific test setup, including tips on getting the best performance out of your probe.
Summary
Passive oscilloscope probes are very sensitive to ground lead inductance and source impedance. It is critical to take these factors into account when determining the connection scheme for probing your signal. By estimating values for ground lead inductance and source impedance you can easily plot the transfer function to get a good idea of what performance you can expect from your probe. Pay special attention to devices under test with very high source impedance, this will essentially turn you’re your probe into an RC filter. For a source impedance of 10k Ohms the bandwidth will be reduced to 1.67 MHz. By understanding the effects of these different variables you can use your passive probe with confidence in a wide variety of environments.
Tomi Engdahl says:
Oscilloscope Mistakes, Part 2
http://www.eetimes.com/author.asp?section_id=36&doc_id=1319495&
The engineering community uses oscilloscopes more than any other piece of equipment, yet many of the published results are questionable at best. Some errors are very common, so we can eliminate a great deal of bad data by considering a few simple but key points. This second part of this four-part series covers probe issues: choosing an incorrect probe or using it improperly.
The three most common probe issues are not calibrating the probe (either for capacitance or for time skew), ringing due to the ground wire, and using 50-Ohm coaxial cable connected to a high-impedance input.
The scope probe is represented as a high impedance in parallel with a high Q capacitance. Any series inductance (either connected to the tip or the ground) will result in a high Q tank circuit and ringing. The ringing frequency will generally be lower than the stated bandwidth of the probe.
An unterminated coaxial cable offers shielding, but it will still resonate with the scope input capacitance and with high Q.
Recommendations
For all high-fidelity measurements up to 100 MHz, remove the ground clip from the measurements. Above 100 MHz, consider an active probe.
A typical oscilloscope probe presents 10-15 pF of capacitance. Many circuits cannot tolerate this, and, at the least, this capacitance can cause significant ringing. In most cases, an active probe is required.
Sometimes the best probe is no probe at all, and a coaxial cable is perfect. This solution also maximizes the sensitivity of the measurement. However, remember that a 50-Ohm coaxial cable must be terminated into 50 Ohms.
Tomi Engdahl says:
Comment from http://www.eetimes.com/author.asp?section_id=36&doc_id=1319495&
Source impedance often dictates what type of probe you can and should use. I often find myself creating my own resistor divider probes with simple coax and a couple SMT resistors. Very low capacitance and minimal loading on high impedance outputs. Active probes are great but sometimes you don’t need them or want them. Been fooled lots of times relying on an active probe. Particularly nasty if you think you can use them for power supply ripple and droop analysis.
Tomi Engdahl says:
Ode to the Oscilloscope
http://www.edn.com/electronics-blogs/outside-the-box-/4439048/Ode-to-the-Oscilloscope?_mc=NL_EDN_EDT_EDN_analog_20150402&cid=NL_EDN_EDT_EDN_analog_20150402&elq=cc01d7e98b164c4c974c7c4a9b84e24b&elqCampaignId=22352&elqaid=25126&elqat=1&elqTrackId=18038e4f3c1742d7ae084eb77c35b751
Tomi Engdahl says:
Make your own probes
http://www.edn.com/electronics-blogs/benchtalk/4441409/Make-your-own-probes?_mc=NL_EDN_EDT_pcbdesigncenter_20160222&cid=NL_EDN_EDT_pcbdesigncenter_20160222&elqTrackId=e385a45ae18b4d219b7bff4aeb662ca7&elq=d432fd139dc541a385d9283877797c5c&elqaid=30960&elqat=1&elqCampaignId=27067
Tomi Engdahl says:
How An Oscilloscope Probe Works, And Other Stories
http://hackaday.com/2017/03/15/how-an-oscilloscope-probe-works-and-other-stories/
The oscilloscope is probably the most versatile piece of test equipment you can have on your electronics bench, offering a multitude of possibilities for measuring timing, frequency and voltage as well as subtleties in your circuits revealed by the shape of the waveforms they produce.
On the front of a modern ‘scope is a BNC socket, into which you can feed your signal to be investigated. If however you simply hook up a co-axial BNC lead between source and ‘scope, you’ll immediately notice some problems. Your waveforms will be distorted. In the simplest terms your square waves will no longer be square.
Crucial to the operation of an oscilloscope is a very high input impedance, to minimise current draw on the circuit it is investigating.
This high resistance does its job of presenting a high impedance to the outside world, but comes with a penalty. Because of its high value, the effects of even a small external capacitance can be enough to create a surprisingly effective low or high pass filter, which in turn can distort the waveform you expect on the screen.
The majority of passive oscilloscope probes contain an attenuator to both isolate the circuit under test from the capacitance of the cable, and compensation capacitors in parallel with each of the resistances to cancel out the effect of the capacitance of the cable. The attenuator is usually chosen to divide the input voltage by ten, hence you will see “10x” probes.
One of the compensation capacitors will be adjustable, to fine-tune the response.
However there are times when it is necessary to measure an output that expects a low impedance, such as a 50 ohm source.
Some ‘scopes have a 50 ohm input mode
Tomi Engdahl says:
Home> Test-and-measurement Design Center > How To Article
Build your own oscilloscope probes for power measurements (part 1)
http://www.edn.com/design/test-and-measurement/4458644/Build-your-own-oscilloscope-probes-for-power-measurements–part-1-?utm_content=buffer9cb72&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer
Modern power supplies are edging upward in operational frequency. The benefits include a reduction in size and weight, plus an increase in energy density. For these designs, engineers are migrating to high-frequency power switch and rectifier technologies. The traditional planar or trench MOSFET switches with rise/fall times 30 nsec to 60 nsec are giving way to power switches such as superjunction MOSFETs, GaN MOSFETs, SiC MOSFETs and SiC Schottky rectifiers that switch in less than 5 nsec.
To view such fast transitions, you typically need an oscilloscope with at least 1 GHz bandwidth. Unfortunately, most commercially available voltage and current probes are woefully inadequate at these high frequencies. The average oscilloscope probe has a bandwidth of less than 300 MHz. Current probes can have bandwidths of 60 MHz to 100 MHz or less. Furthermore, high-frequency voltage probes often cost over $12,000 and slightly better current probes start at $4,000. For power engineers who work for mid-sized companies, there is only one path: build your own probes.
Tomi Engdahl says:
The AKL-PT1 is a handheld 10:1 transmission-line probe for 50 ohm systems.
An Open Source 2GHz Passive Oscilloscope Probe
https://www.hackster.io/news/an-open-source-2ghz-passive-oscilloscope-probe-66a8abcb8124
The AKL-PT1 comes fully assembled or as a bare PCB that you can solder yourself.
The AKL-PT1 is a handheld 10x transmission-line probe, which is essentially a precision resistor connected to the scope through a coaxial cable. This design results in lower loading at high frequencies than a traditional resistor capacitor. The tradeoff is higher DC loading, and that you’ll need an oscilloscope with 50 ohm input terminations.
According to Zonenberg, the current prototypes have performed well in testing:
500Ω ± 0.1% loading at DC
Nominal insertion loss across 50Ω load: -20.5 dB
Flat ±0.5 dB from DC to 0.91 GHz
Flat ±1 dB from DC to 1.98 GHz
-3 dB bandwidth of 2.19 GHz
Rise time: 107 ps 20-80%, 161 ps 10-90%
https://www.kickstarter.com/projects/azonenberg/akl-pt1-2-ghz-passive-oscilloscope-probe
Tomi Engdahl says:
https://github.com/azonenberg/starshipraider/tree/master/boards/probes/handheld-resistive-probe
Tomi Engdahl says:
Are you measuring your circuit or your scope probe?
https://www.edn.com/are-you-measuring-your-circuit-or-your-scope-probe/
Tomi Engdahl says:
Bud Bennett needed a probe that could grab a 1V differential signal riding on a 60Hz 125VAC mains voltage, but many of the commercial probes available on the market weren’t suitable for that purpose, so he did what any engineer would do in that situation: He created his own for his Rigol DS1102E o-scope.
Build a 10X 100MHz Differential Probe for Signals Embedded in Common-Mode Voltages
https://www.hackster.io/news/build-a-10x-100mhz-differential-probe-for-signals-embedded-in-common-mode-voltages-1450268eceec
This DIY probe features an input impedance of 20MegΩ// 1.25pF, a differential gain of 1/10 V/V, and a common-mode range of ±340V.
Electrical engineer Bud Bennett needed a probe that could grab a 1V differential signal riding on a 60Hz 125VAC mains voltage, but many of the commercial probes available on the market weren’t suitable for that purpose, so he did what any engineer would do in that situation: He created his own for his Rigol DS1102E o-scope.
Bennett designed his 10X 100MHz Differential Probe using a custom PCB, 5V DC adapter to power the probe, and an SMA to BNC pigtail to connect the probe to the scope.
The 10X 100MHz Differential Probe offers an input impedance of 20MegΩ// 1.25pF-differential (10MegΩ//2.5pF each terminal to GND), a differential gain of 1/10 V/V, and a common-mode range of ±340V (240VAC produces a sine wave 679V peak-peak). It also features a CMRR of >90dB @ DC (~60dB @ 1MHz), a differential voltage range of ±24V for 240VAC common-mode/±24V for 0V common-mode, a bandwidth of 100MHz, and a DC offset of < 20mV.
https://hackaday.io/project/169390-a-10x-100mhz-differential-probe/details
Tomi Engdahl says:
with a 240VAC input to ±24V with small changes to component values. No change to the PCB layout.]
https://hackaday.io/project/169390-a-10x-100mhz-differential-probe/details
Tomi Engdahl says:
A 1x, 100 MHz, 35 V common mode diff probe
I needed a differential probe for BLDC motor ESC development and adapted Bud’s design for my needs
https://hackaday.io/project/175351-a-1x-100-mhz-35-v-common-mode-diff-probe
Tomi Engdahl says:
Christoph Redecker’s Common-Mode Differential Probe Vastly Improves His Oscilloscope for ESC Work
https://www.hackster.io/news/christoph-redecker-s-common-mode-differential-probe-vastly-improves-his-oscilloscope-for-esc-work-f7a6dd0684d3
Designed to improve signal comparisons for electronic speed control projects, Redecker’s probe is based on Bud Bennett’s design.
Tomi Engdahl says:
An Open Source 2GHz Passive Oscilloscope Probe
The AKL-PT1 comes fully assembled or as a bare PCB that you can solder yourself.
https://www.hackster.io/news/an-open-source-2ghz-passive-oscilloscope-probe-66a8abcb8124
Tomi Engdahl says:
Turn an Old Analog TV Into a Simple Oscilloscope
Follow this tutorial to turn a TV into a simple oscilloscope.
https://www.hackster.io/news/turn-an-old-analog-tv-into-a-simple-oscilloscope-36e0558b808e
Tomi Engdahl says:
You Can Make an Oscilloscope Out of a Cheap USB Sound Card
https://www.hackster.io/news/you-can-make-an-oscilloscope-out-of-a-cheap-usb-sound-card-cf3d424d7dd8
Follow this tutorial to turn a USB sound card into an oscilloscope that can be used with your computer.
Tomi Engdahl says:
Christoph Redecker’s Common-Mode Differential Probe Vastly Improves His Oscilloscope for ESC Work
Designed to improve signal comparisons for electronic speed control projects, Redecker’s probe is based on Bud Bennett’s design.
https://www.hackster.io/news/christoph-redecker-s-common-mode-differential-probe-vastly-improves-his-oscilloscope-for-esc-work-f7a6dd0684d3
A 1x, 100 MHz, 35 V common mode diff probe
https://hackaday.io/project/175351-a-1x-100-mhz-35-v-common-mode-diff-probe
Tomi Engdahl says:
A 10X 100MHz Differential Probe
A DIY oscilloscope probe to dig small differential signals embedded in high common mode voltages.
https://hackaday.io/project/169390-a-10x-100mhz-differential-probe
Tomi Engdahl says:
Little Bee Is an Open Source Current and Magnetic Field Probe
https://www.hackster.io/news/little-bee-is-an-open-source-current-and-magnetic-field-probe-3c86cd9fa835
This tool effectively debug and analyze electronic devices, plus function as a sensitive magnetic field probe and a current probe.
We must determine voltages and currents in our designs. It’s a given. Using an oscilloscope is simple. Current probes are cool but pricey at times. In walks an alternative − Little Bee, a low-cost, high-performance current and magnetic field probe from Weston Braun that’s capable of effectively debugging and analyzing electronic devices.
The Little Bee is built around an Anisotropic Magnetic-Resistive (AMR) magnetic sensor, making its performance comparable to probes based on fluxgate magnetometers and those hybrid models combining AC current transformers with DC Hall effect sensors. It features a bandwidth that can be adjusted between 1 MHz and 10 MHz, an SMA output connector, connectivity to 1 MΩ impedance oscilloscope input, and it has automatic offset adjustment. Little Bee only requires one AA battery to operate! Neat.
https://www.crowdsupply.com/weston-braun/little-bee
Tomi Engdahl says:
Make Your Own Solder-In Passive Oscilloscope Probes
This DIY solution makes it easy to probe multiple points in a circuit with a scope.
https://www.hackster.io/news/make-your-own-solder-in-passive-oscilloscope-probes-7728c12ad11a
Tomi Engdahl says:
This Modular Differential Probe Shows Great Attention To Detail
https://hackaday.com/2021/08/25/this-modular-differential-probe-shows-great-attention-to-detail/
[Petteri Aimonen] presents for us a modular differential probe, as his entry into the 2021 Hackaday Prize.
This project shows a simple and well polished implementation of a differential-to-single-ended preamplifier, which allows a differential signal to be probed and fed to an oscilloscope via a BNC cable.
Modular differential probe
https://hackaday.io/project/181065-modular-differential-probe
100 MHz differential probe for oscilloscopes, with modular accessories to suit both high and low voltage use.
Tomi Engdahl says:
A 10X 100MHz Differential Probe
https://hackaday.io/project/169390-a-10x-100mhz-differential-probe
A DIY oscilloscope probe to dig small differential signals embedded in high common mode voltages.
Tomi Engdahl says:
EEVblog 1414 – Turning it up to 11 (1100V)
https://www.youtube.com/watch?v=V93Rnco-wKg
Can Dave destroy the Micsig DP10007 high voltage differential probe by turning the voltage up to 1100V RMS?
Plus a teardown of course.
https://www.eevblog.com/product/hvp70/
Tomi Engdahl says:
This very low-cost oscilloscope probe adapter offers more versatility in probing with less frustration.
Learn more: http://arw.li/6184JMxZa
#EDN #3DPrintableOscilloscope
3D-printable oscilloscope probe to wire adapter
https://www.edn.com/3d-printable-oscilloscope-probe-to-wire-adapter/?utm_source=edn_facebook&utm_medium=social&utm_campaign=Articles
In the lab, a common frustration is supporting an oscilloscope probe for continuous monitoring. There are many probe holders available: some good, some not so good, and some very expensive. Presented here is an adapter that allows you to solder the probe to the PCB
The adapter can be configured with wire ends to connect headers or proto boards. Items such as microclips, grabbers, banana plugs, headers, etc., can also be attached (Figure 2). The best part is that it is almost free, as it can be 3D printed.
The body of the adapter can be printed on any 3D printer capable of about 0.12mm resolution. The only other parts required are two spring terminals and some wire. The spring terminals are Molex 0008500113, which are readily available from various suppliers.
Tomi Engdahl says:
#338: Probe Tips: Beware of capacitive loading of oscilloscope probes on your circuit operation
https://www.youtube.com/watch?v=sPSJnj7gVJA
The capacitive loading of your oscilloscope probe might affect the operation of your circuit – certainly something to keep in mind when probing around.
1X passive probe can have 100pF or more of capacitive loading which can dramatically affect many circuits. 10X probes are typically 8-15pF or so, with some exceptions. Active FET probes offer very low capacitive loading, typically under 1pF.
Tomi Engdahl says:
#924 $9 DIY FET Probe vs Tektronix FET Probe
https://www.youtube.com/watch?v=E-G5iNrt9CM
https://www.ebay.com/itm/333599037092?mkevt=1&siteid=1&mkcid=2&mkrid=711-153320-877651-5&source_name=google&mktype=pla_ssc&campaignid=10454314772&groupid=112166165668&targeted=pla-293946777986&MT_ID=&adpos=&device=c&googleloc=9072483&itemid=333599037092&merchantid=116792603&geo_id=154&gclid=EAIaIQobChMIqOOVxaDW8wIVnwCiAx2WNwqoEAQYASABEgKtZfD_BwE
Tomi Engdahl says:
TSP #182 – Antikernel Labs Inexpensive Multi-GHz Transmission Line Probe Review & Experiments
https://www.youtube.com/watch?v=eZhMIR0l3xU
In this episode Shahriar takes a look at the design and performance of the open-source ALK-PT1 passive probe. This probe uses is based on a classical transmission line feed structure and has gone through many iterations to improve its performance. The design tradeoffs of various passive probes are explored and the performance of the ALK-PT1 is measured both in S-parameters domain and time domain using NRZ serial data at various data rates.
You can get your own AKL-PT1 Passive Probe from Antikernel Labs:
https://www.antikernel.net/products.html
Tomi Engdahl says:
Six Tips for Power Integrity Debug with an Oscilloscope
Dec. 1, 2021
Detailed real-world advice and demonstrations of multiple techniques on a sample microcontroller board can help you debug your power integrity problems fast.
https://www.electronicdesign.com/technologies/test-measurement/article/21182573/teledyne-lecroy-six-tips-for-power-integrity-debug-with-an-oscilloscope?utm_source=EG%20ED%20Analog%20%26%20Power%20Source&utm_medium=email&utm_campaign=CPS211130095&o_eid=7211D2691390C9R&rdx.ident%5Bpull%5D=omeda%7C7211D2691390C9R&oly_enc_id=7211D2691390C9R
What you’ll learn:
Remember fundamentals and practice situational awareness in taking measurements.
It’s not only using the right probe, but it’s also using the probe right.
Eliminating measurement artifacts is tricky, but not impossible.
An oscilloscope is an essential instrument for making power integrity (PI) measurements, but to apply it effectively, you’ll need situational awareness. Be aware of the oscilloscope features, the signal features, and potential measurement artifacts that could impede your view of the real signal. Key scope features include the bandwidth, sample rate, time base, vertical scale, input impedance, channel bandwidth, and probe bandwidth.
Demonstrations of measurements on sample microcontroller boards illustrate six tips that you can apply to your own PI debug tasks. In addition to an oscilloscope, you will need high-performance probes and the ability to choose the optimum versions—including 10x passive, power-rail, near-field, current, and differential probes—for your application.
Tip 1: Get the most out of your 10x passive probe
The 10x passive probe is the workhorse probe for most oscilloscope measurements. The first thing you want to do is apply color bands on your 10x passive probes that match the color of the corresponding oscilloscope trace to keep track of what you’re measuring
Tip 2: Use dc coupling for power-rail measurements
If you’re looking for small variations in noise on a 5-V power rail, you may be inclined to use ac coupling. It lets you zoom in and out on the signal without having to reposition the trace on the screen every time you change the vertical scale. However, when you do that, you lose information about slow drift or other variations, because everything below about 10 Hz is filtered out.
Tip 3: Use a rail probe to measure switching noise
When looking at the power rails, consider using a rail probe, such as the Teledyne LeCroy RP4030. The RP4030 is a 4-GHz, dc-coupled active probe designed to measure the low impedances of the power rails but with the benefits of a high signal-to-noise ratio (SNR) and high bandwidth.
Like the 10x passive probe, the rail probe includes two paths. First is a passive ac-coupled path for high frequencies that acts like a high-pass filter with a pole frequency of about 10 to 100 kHz. The second path consists of two inverting amplifiers with a 16-bit digital-to-analog converter (DAC) that enables precision offset control. This path together with the oscilloscope’s input impedance acts as a low-pass filter, and again, it’s necessary to align the poles of the high- and low-pass filters to obtain a flat response.
Tip 4: Use a near-field probe to locate EMI problems
When looking for potential EMI problems during the pre-compliance test, opt for a near-field probe. Note that the near-field probe is essentially a low-impedance loop, so take care to connect it to a 50-Ω oscilloscope input—not a 1-MΩ input—to prevent reflections and ringing. In addition, when probing a microcontroller board, a useful technique is to trigger the oscilloscope on a switching I/O signal, so that the observed waveform will be synchronized with the microcontroller’s clock.
Tip 5: Use a current probe to find ground loops
A high-sensitivity current probe can help measure common ground-loop currents found in USB cables and other external connections. These currents can arise from the different ground potentials of multiple instruments connected to the microcontroller demo board, for example. They can fluctuate quickly if the ground potential differences result from switching within the demo board or the devices connected to it.
connecting a ground pin on the microcontroller board to ground on another external device plugged into the wall can result in common currents reaching 75 mA. Only 5 mA is required to fail an FCC part 15 class B test. The current probe is useful in viewing common currents
Tip 6: Use a differential probe to check a microcontroller’s current draw
To measure the actual current that the microcontroller draws in real-time, use a differential probe. First, insert a sense resistor—for example, 0.5 Ω—in the series path of the power rail, and then measure the voltage across it. You could use two single-ended probes, one to measure the voltage to ground on each side of the resistor. However, that would involve subtracting one large number from another to get the voltage across the resistor, which can introduce inaccuracies.
Instead, use the differential probe, which is designed to measure small voltage differences with a large common dc offset. You can use the differential probe and sense resistor to measure inrush as well as steady-state current.
Summary
In conclusion, keep in mind that it’s easy to do a measurement, but hard to do so without artifacts. Practice situational awareness. Make sure you use the right probe for the right application. Use the 10x passive probe with low-inductance ground connections to the extent possible. Then, use a rail probe for measurements requiring high bandwidth and SNR, use a near-field probe for pre-compliance EMC testing, turn to a current probe to measure common currents, and use a differential probe with a series resistor to measure inrush and steady-state currents.
Tomi Engdahl says:
EEVblog 1445 – How to Simulate an Oscilloscope Probe in LTSPICE
https://www.youtube.com/watch?v=kWSCVq7FgAE
How to simulate a x1 oscilloscope probe in LTSPICE.
And how to use the lossy transmission line model in practice with the spice directive.
Tomi Engdahl says:
Building a high-voltage 1:1000 probe
https://www.youtube.com/watch?v=Rl8I4PO66Uw
his video is about building a 1:1000 high voltage probe, mainly for my scope but also usable for multimeters.
I considered publishing plans but then properly rated high voltage components are not easy to get and so I rather spent a bit more time on the design principles, so you can adopt the circuit to whatever component values you managed to get and of course what input impedance & capacitance your scope has.
WARNING:
If you build and use this probe, you do so at your own risk!
High voltage can seriously hurt you and damage your equipment!
parts:
Vishay 10MΩ 1W Metal Glaze Resistor ±5% VR68000001005JAC00 RS stock# 683-5326 10 for £4.70 ex VAT
Vishay Single Layer Ceramic Capacitor SLCC 15pF 3kV dc ±20% U2J (N750) Dielectric 564R Series Through Hole RS Stock# 831-3155 5 for £2.40 ex VAT
Vishay Single Layer Ceramic Capacitor SLCC 1.5nF 2kV dc ±10% S3N Dielectric F Series Through Hole RS Stock# 716-7254 10 for £2.50 ex VAT
RS PRO Black Flame Retardant Epoxy Potting Compound RS Stock# 199-1402 50gm £5.11 ex VAT
Tomi Engdahl says:
https://hackaday.com/2022/04/23/a-fet-oscilloscope-probe-for-higher-frequencies/
Tomi Engdahl says:
Scope Probe Caddy
https://hackaday.io/project/185020-scope-probe-caddy
I needed a place to hold my scope probes above the festoon of wires and junk on my bench. Here’s my solution.
I used OpenSCAD to design a two-part clip and receptacle that mounts on the back of a scope probe connector. The receptacle is a place for the business end of the scope probe to inhabit until the next time I need to probe something.
Tomi Engdahl says:
Super Simple Scope Shambles Solution
https://hackaday.com/2022/04/29/super-simple-scope-shambles-solution/
Sometimes the projects we write up for Hackaday require their creators to produce pages of technical explanation, while others need only rely on the elegance of the hack itself. The Scope Probe Caddy from [Tonyo] has probably one of the shortest write-ups we’ve linked to from a Hackaday piece, because its utility is self-evident just by looking at it.
https://hackaday.io/project/185020-scope-probe-caddy
Tomi Engdahl says:
Clever Scope Probe Drawers Keep Your Workbench Tidy
https://hackaday.com/2022/05/01/clever-scope-probe-drawers-keep-your-workbench-tidy/
Probes are an essential component of a good oscilloscope system, but they have the nasty habit of cluttering up your workbench. If you have a four-channel scope, it’s not just several meters of cable that get in the way everywhere, but also four sets of all those little clips, springs, cable markers, and adjustment screwdrivers that need to be stored safely.
[Matt Mets] came up with a clever solution to this problem: a 3D printed cable organizer that neatly fits below your scope. It has four drawers, each of which has enough space to store a complete probe and a little compartment for all its accessories. A cable cutout at the front allows you to keep the probes plugged in even when they’re not in use.
https://twitter.com/cibomahto/status/1519934349935890433
Tomi Engdahl says:
EEVblog #1367 – 5 Types of Oscilloscope Passive Probes COMPARED
https://www.youtube.com/watch?v=rzo4Ntxqu1E
Tomi Engdahl says:
Measuring Inrush Current with an Oscilloscope, Circuit Breakers and Clamp Meters
https://www.youtube.com/watch?v=-rM2EtkXCbE
In this video I use an oscilloscope to measure the inrush current caused by an induction motor starting with a variable speed drive (VFD). I do this to show some of the challenges clamp meters can face getting this measurement as an RMS reading when there is distortion of the waveform.
I also explain how an electrothermal circuit breaker works by preventing overloads and short circuits.
* Circuit breaker instantaneous tripping current, should it be RMS or peak current?
Equipment used:
* Agilent / Keysight DSO-X 2000 Oscilloscope
* HT Instruments HT9022 Power Clamp Meter
* Yokogawa CW10 Power Clamp Meter
* Fluke 43B Power Quality Analyzer
* Thermal magnetic circuit breaker
Tomi Engdahl says:
Active Signal Tracer Probe Has AGC
https://hackaday.com/2022/06/24/active-signal-tracer-probe-has-agc/
Tomi Engdahl says:
Electronic Probes (in the mid 1950s)–Isolation and direct probes
https://www.industrial-electronics.com/gern_probes_54_7.html
Tomi Engdahl says:
https://www.instructables.com/DIY-1GHz-Active-Probe-for-Under-20/
Tomi Engdahl says:
Oscilloscope probe impedance at various frequencies
https://www.dropbox.com/sh/ftcxyzq3pgl33r2/AACie5JV-kItdZje9kkPC6kFa/Meter%20Impedance%20Charts?dl=0&subfolder_nav_tracking=1
Tomi Engdahl says:
1970 Electronics Technology: The CATHODE RAY OSCILLOSCOPE principles & applications, CRT Tektronix
https://www.youtube.com/watch?v=auPtNtODXvs
Tomi Engdahl says:
Active Probe, Schematic Included
https://www.youtube.com/watch?v=NlbC-cMIBTY
Tomi Engdahl says:
#65 Shop Talk Sniffing RF signals safely
https://www.youtube.com/watch?v=wQ-oFk_VWog
Tomi Engdahl says:
EEVblog #1368 – Active Oscilloscope Probes COMPARED (Part 2)
https://www.youtube.com/watch?v=WlSb8hdFtTY
Tomi Engdahl says:
EEVblog #1367 – 5 Types of Oscilloscope Passive Probes COMPARED
https://www.youtube.com/watch?v=rzo4Ntxqu1E
Dave looks at the pros and cons of 5 different types of oscilloscope passive probes.
Switchable x1/x10, Fixed x10, High voltage single ended, DIY Transmission line Z0 probe, and BNC to banana/croc leads.
Tomi Engdahl says:
EEVblog #1178 – Build a $10 DIY EMC Probe
https://www.youtube.com/watch?v=2xy3Hm1_ZqI
Tomi Engdahl says:
EEVblog #1367 – 5 Types of Oscilloscope Passive Probes COMPARED
https://www.youtube.com/watch?v=rzo4Ntxqu1E
Dave looks at the pros and cons of 5 different types of oscilloscope passive probes.
Switchable x1/x10, Fixed x10, High voltage single ended, DIY Transmission line Z0 probe, and BNC to banana/croc leads.
EEVblog #1368 – Active Oscilloscope Probes COMPARED (Part 2)
https://www.youtube.com/watch?v=WlSb8hdFtTY&t=673s
Part 2, this time looking at different types of active oscillocope probes.
Single ended active FET probes, differential active FET probes, current clamp probes, high voltage differential probes, positional current probes, and EMC magnetic and electric field probes.