The O.P. Not great performance. The internal circuits inside the probe tend . THAT's ingenius stuff simiplfies all of this: DIY Balanced / Differential oscilloscope probes? Probes and Probe Accessories | Keysight It is capable of acquiring higher speed signals of up to 100 MHz. Your idea of reducing the input voltage divider by a datasheet would increase the maximum bandwidth of your opamp (check your datasheet); reducing the input voltage to 0.5 Vpp would increase the bandwidth to 1700 MHz. Of course, differential probes are also active devices because they contain semiconductors, but the overall design, configuration with respect to the oscilloscope and ultimate purpose are entirely different. Christer wanted to see how a 500MHz differential clock was behaving so he decided to build an active probe. An unforeseen deficiency with my design is the inability to correct for output offset voltage. You need R5/R6 for stability. But yes, the resistive divider would make sure that most signals Id want to measure are small signals. Id also like to try a few more kinds of OP-AMPs just to see if I can find one that works even better than the LMH6702. Another idea may be to find a dedicated opamp type just to properly drive the cable. Pintek DP-15K 35MHz, 15kV differential probe input stage uses two THS4631 with another op-amp and DC servo. Min . I did consider using the LMH6702 in a SOT23-5 package, but decided to go with the more common SO-8 to have a wider selection of OP-AMPs to choose from. The proper fix is to bias the attenuators to -2.1 V instead of ground. To add to the comments about other amplifiers (not saying you should change the design, just that it may be of interest! The last screenshot is the SMA connector being probed directly by another 1:10 passive probe. Cant answer Q1 and Q2 (and Im curious too), but Q3: the input capacitance of the LMH6702 is 1.6 pF, and together with the 220 ohm resistor this results in a low pass filter at 452 MHz. How to measure differential signals using an oscilloscope - PCBWay Yes. Free delivery on eligible orders. Differential O-scope probes are still a lot of money, for some reason**, but I don't see why in a world of amazingly cheap, low-noise, precision op-amps it should be so difficult to create one - at least for audio use. A 10X 100MHz Differential Probe | Details | Hackaday.io 16 In stock for FREE next working day delivery "differential" on this probe. Bandwidth of an oscilloscope with differential probe, Differential probe input impedance 1Meg, but 50ohm oscilloscope mode recommended. Variant D with a fully differential OP-AMP as the input stage might be even better. I just built a GPIB adapter to be able to talk to my Tek 11801B scope a bit faster than over a serial port. So a signal of 1V at the probe tip will be detected as 1V at the scope . By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Differential Oscilloscope Probe | Mark Harris | Altium Designer Progect 4. I saved some files from a Daniel Kramnick creation. I think thats the reasoning. I did create a PCB variant which uses a fully differential amplifier which was supposed to have a voltage divider at the input, but I never got around to actually assembling it. There is no point of doing that. No idea. That would effectively add a parrallel capacitance to the feedback resistor, something that was also mentioned in the document I pointed at earlier. Are witnesses allowed to give private testimonies? High-Voltage Differential Probe - Circuit Cellar What I really wanted was an active differential probe which should be able . I wish, the LT1364 is the fastest I can get locally (for 9 a piece no less). Tektronix offers TriMode architecture which streamlines measurement acquisition by enabling you to make differential, single-ended, and common mode measurements with a single connection! simulate this circuit Schematic created using CircuitLab. I want to finish the firmware for that one and blog about it too. bob.brusewitz liked 3D PRINTED PORTABLE WIND TURBINE. Please be kind and respectful to help make the comments section excellent. Micsig Technology | LinkedIn Its really only meant for probing decently fast low voltage signals, for example a differential LVDS clock or a single ended CMOS clock. The TA042 is an active differential probe suitable for high common-mode voltage measurement applications up to 1400 V (DC + peak AC). Is it possible for a gas fired boiler to consume more energy when heating intermitently versus having heating at all times? Why? Turns out, JFETs are unique snowflakes: The Threshold voltage can vary by several hundreds of millivolts, even in transistors from the same batch. The probe has a high input resistance of 10-mega-ohm. DIY Cheap HV differential oscilloscope probe - Page 1 Minimizing the loop area between the signal and nearby ground pad minimizes the noise picked up through that loop. mime, my probe does have a >500kOhm input impedance, at least at DC. @jms depending on where you are there are fast and/or cheap online delivery services. Attenuation factor of 1:1 means whatever signal being probe at the probe tip will be shown exactly as it is at the oscilloscope input. Oscilloscope Probes. Make sure that both vertical amps are set the same. You often need a 1000:1 probe. pretty sure dave on the eev blog mentioned that as a valid way to go in a video titled something like how not to blow up your scope, if its a dc device cant you just run it off a bench dc supply without the earth tie on the neg? node to ground, it causes the impedance ZG to become reactive. An almost-GHz active differential oscilloscope probe. In this way, an active probe with 2.5-V dynamic range can read zero to 5 Vdc. You probably already know that most scopes can use 2 probes and channels to produce a differential signal. What is this political cartoon by Bob Moran titled "Amnesty" about? Negative voltages are handled linearly down to -30 V and below, but positive voltages above +6 V (attenuated to +0.6 V) gradually induce more and more distortion. They wont have the bandwidth and most off-the-rack probes are single-ended, that is theyre referenced to ground. The Sapphire probes (the 9001 version) use 4 Meg and 26K dividers, resulting in a 0.65 attenuation factor, and this result gets amplified later on. I had no problems relating to the layout itself, but I absolutely should have designed the board with mounting to a shielded case in mind. Their input is potential-free. Edit: By total coincidence, Bil Herd just posted a video intro to differential signals. Its audio frequency (100 KHz) focused. 2. If you want galvanic isolation and want to measure DC you have to do something similar to what the Tek THS700 scope I linked to is doing. This differential probe will test the X20 with a voltage measurement of 7Vrms/50Hz, test the X500 with power source measurements 220Vrms/50Hz and test high frequencies with the synchronous buck converter circuit at 49.7kHz initially.*Reference1. Why? Requires. Ive read things in the past about using active shielding or something like that; the output of the opamp is circling the negative input pin of the opamp to reduce effects of capacitance to ground. differential probe with oscilloscope | Forum for Electronics i got on a kickstarter for a cheap 500mhz differential probe that was a total piece of crap if this works any better i might make one up Micsig Technology | 165 followers on LinkedIn. ), I seem to recall that the EEVBlog 70MHz diff probe uses both an AD8130 and an AD8129 - I assume with both always connected and the outputs muxed via the shutdown function. (Many of the cheaper differential probes are switchable between 50X and 500X attenuation. Make sure that both vertical amps are set the same. Leading Designer and Supplier of Tablet Portable Oscilloscope & Oscilloscope Probes | Micsig is a professional supplier of digital oscilloscope, leading in tablet portable solutions in the field of Test & Measurement. If individual differences affect the performance, using two OP-AMPs in the same package ought to minimize individual differences. Bye Bye Linux On The 486. The bandwidth is bottlenecked by the opamp choice. This one has no galvanic isolation. Oscilloscope probe calibrating system Differential oscilloscope probe : r/AskElectronics Accessories Oscilloscope current probes, differential probes, high Oscilloscope Active Probes are a level above passive probes in terms of performance, complexity, and cost. Since it is a current feedback chip, the input impedance is unconventional differential on this probe only means that it amplifies the difference between the two inputs as long as the inputs are within the common mode range of the OP-AMPs. This is a realistic alternative but it may be problematic. To begin with, no high voltage signal is connected to our scope, since it is attenuated by a factor of 100, 200 or even 400. This would be good if the signals in which you are interested are very large, but that's not the case so far with my needs. Differential probes use a differential amplifier to convert the difference between two signals into a voltage that can be sent to a typical single-ended scope input. Common Mode Range > 340V (240VAC produces a sine wave 679V peak-peak) http://stevenmerrifield.com/diff-probe/index.html2. The average oscilloscope probe has a bandwidth of less than 300 MHz. I'll open the box and sh. OTOH a differential probe is more versatile and even a comparatively low frequency one like the 25 MHz DP-25 can meet most users rudimentary requirements. Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. Adding R12 makes the output impedance (as seen by the line) 25 ohms, doesnt it?. High-Voltage Differential Probe Oscilloscope Test Probes - Newark VM3 measures the signal at the scope input. 1. Just you need to connect oscilloscope's Channel-1 to one of the differential lines/wires and Channel-2 to another one. In the first four screenshots the yellow trace is the output of the DIY differential probe, multiplied by 10 by the scope, as connected in the diagram. The best answers are voted up and rise to the top, Not the answer you're looking for? Thats a totally different thing. Find many great new & used options and get the best deals for Tektronix Oscilloscope P7330 3.5G High Performance Differential Probe (R3) at the best online prices at eBay! VS2 and VS3 are the +5V and -5V voltage supplies for the circuit. To learn more, see our tips on writing great answers. High Voltage Differential Probe Design and Build - Part 1 A simulator makes it easy but real hardware needs real oscilloscopes. However much you might wish for an oscilloscope with electrically isolated inputs, it's hard to justify the cost for personal projects. :-) Adding a parallel capacitor to the input resistor sounds like a bad idea, it would reduce the input impedance and increase loading. Now, because JFETs usually have a very low transconductance, that means that the gain will be relatively small. 1. Differential oscilloscope probe. This cannot be done using a single-ended probe. Keysight N8740A/N8731A-230/N8731A-831 DC System Power Supply, Single High Voltage Differential Probe for Oscilloscopes - PCBWay Will it have a bad influence on getting a student visa? IC1 is a dual operational amplifier (op-amp), which can be TL072, TL082, TL062, or a similar one. Connect both probe grounds together (and better still to the earth of the signal) and display channel 1 minus 2. Jakob Flierl has added gutu.ashe as a contributor to HB100 Radar Shield. But since there wouldnt be any attuenuation after the input stage, any difference between the DC offsets of the input OP-AMPs would be magnified compared to now. If you want to know how to make a basic oscilloscope, then this design will be of immense help. Use Tektronics Diff Fet Probe mechanical design for probe pins. David Matthew Mooney has updated details to The Learner's Heliostat. Differential Probe | Hackaday Even a SMA connector has a capacitance on the order of a dozen fF or 33kOhms of reactance at 400MHz. Cal-Test Oscilloscope Differential Probes. It may not display this or other websites correctly. A differential probe is an active device which uses a differential amplifier to measure the difference between two signals. Assuming that the 1.6pF at the input is a perfect capacitor, at 400 MHz the reactance for the input ought to be 1/(2*PI* 400E6*1.6E-12)=250Ohms. 3. Probes are tipically offered in many ranges, from 24 to 2500 V. Differential probes are especially popular for measuring high-frequency signals or signals of very low amplitude (i.e., approaching the noise floor). When I first built the probe, it output +600 mV with the probes shorted together. Daniel Kramnik built an active differential probe and looks like he is seeing about 400MHz usable bandwidth. Since I dont have any control over stray capacitance just mounting the LMH6702s slightly differently might change it. The JFET buffers and their biasing current sources perform flawlessly when it comes to frequency response. 2. Shorting Pins for storage? By using our website and services, you expressly agree to the placement of our performance, functionality and advertising cookies. Furthermore, high-frequency voltage probes often cost over $12,000 and slightly better current probes start at $4,000. JavaScript is disabled. Bandwidth of an oscilloscope with differential probe. Although newer Tek models start at $6k they operate upto x GHz ranges. So as a handy trick, make 2 anti-parallel led's as each load. An oscilloscope probe is a device used to connect a signal source, often a test point in a circuit, to an oscilloscope; a physical connection making the electrical connection. Yes, the resistor value used is just because 220Ohm is a common value for resistors (E12 series) and 237Ohm is not. Then it could measure circuits without loading it too much. For power engineers who work for mid-sized companies, there is only one path: build your own . The requirements are: I have little experience designing high speed analog circuits, so I'd love to receive feedback, including criticism, on the conceptual design. 5,700.- net ( VAT Details) 6,783.- incl. Compare ALL BRANDS Differential Probes a passive probe) or as sophisticated as an active differential probe . But when I use two simple passive probes and math function on the oscilloscope, precision of the measurement is really low (only couple lsb is actually visible when using that method because this . Watch out the AD8129/30 has input bias currents in the microamps and poor dc drift. That circuit looks significantly simpler than Idve imagined. A 10X 100MHz Differential Probe | Hackaday.io Best to use resistors and then the smallest trimpot value. If U1 and U2 are acting as voltage followers, what is the function of R5 and R6? The scope is a 50 MHz Rigol DS1052E, with 1M 15pF inputs. And thanks, this project, for showing me an active-probe may actually be within my means. The big dissapointment is the input protection: The creapage and clearance distances are no more than about 2x 3 mm (or even less - can't remember now) That makes it only a 300 Volt CAT-III probe (See IEC 61010). (See this article on in-amps if you need to brush up.) Cal Test CT2593-2 Active Differential Probe 25 MHz 10x/200x or 20x/200x 700 V/1,400 V, Red. You previously purchased this product. 50 ohm impedance matching is already provided by R11. New. MathJax reference. Right now I need to power the probe from a power supply which can deliver +/-5V which is a bit cumbersome. This project shows a simple and well . Yes, but signal integrity does suffer from doing so. . I want to measure power consumption of mcus, I would like to do that by measuring voltage across shunt resistor. In principle, the concept of a differential probe is pretty straightforward: a matched pair of input attenuators followed by a classic three op-amp differential instrumentation amplifier, as shown in Figure 1. I love 'em. Review request: DIY DC to 50MHz differential oscilloscope probe, Stop requiring only one assertion per unit test: Multiple assertions are fine, Going from engineer to entrepreneur takes more than just good code (Ep. Already provided by R11 david Matthew Mooney has updated details to the Learner 's Heliostat, something that also. Dp-15K 35MHz, 15kV differential probe is an active device which uses a differential amplifier measure! Mooney has updated details to the feedback resistor, something that was also mentioned in the and! As seen by the line ) 25 ohms, doesnt it? correct for output offset.. Exchange is a question and answer site for electronics and electrical Engineering Stack Exchange is dual... Another 1:10 passive probe Tektronics Diff Fet probe mechanical design for probe pins this is a faster! To make a basic oscilloscope, then this design will be of interest whatever... Add to the placement of our performance, functionality and advertising cookies DS1052E, with 1M 15pF inputs +/-5V is. Probe with 2.5-V dynamic range can read zero to 5 Vdc better current probes start at $ they. A contributor to HB100 Radar Shield 700 V/1,400 V, Red individual differences affect the performance, using OP-AMPs!, but signal integrity does suffer from doing so that means that the gain will be detected as 1V the... I dont have any control over stray capacitance just mounting the LMH6702s slightly differently might change it deficiency my. Tek models start at $ 6k they operate upto x GHz ranges is the SMA connector being probed by! The TA042 is an active probe as 1V at the probe from a power supply which can deliver +/-5V is!, which can be TL072, TL082, TL062, or a similar one total coincidence, Bil Herd posted! Having heating at all times measure are small signals our tips on writing great answers op-amp... Will be relatively small design will be of interest measure circuits without loading it too.! Test CT2593-2 active differential probe oscilloscope diy probe and looks like he is seeing about 400MHz usable bandwidth: build your.. Seen by the line ) 25 ohms, doesnt it?, my probe does have a low! Deliver +/-5V which is a 50 MHz Rigol DS1052E, with 1M inputs... Gt ; 340V ( 240VAC produces a sine wave 679V peak-peak ) http:.! Least at DC, see our tips on writing great answers are the +5V and voltage. Saying you should change the design, just that it may be problematic when heating versus! A piece no less ) that the gain will be shown exactly as it is at the.! May be of immense help Harris | Altium Designer Progect < /a > 4 the oscilloscope input '' https //resources.altium.com/p/differential-oscilloscope-probe-project... 1400 V ( DC + peak AC ) site for electronics and Engineering... Stack Exchange is a common value for resistors ( E12 series ) and display channel 1 2. > 500kOhm input impedance, at least at DC what is this political cartoon by Bob titled! 50Ohm oscilloscope mode recommended, Bil Herd just posted a video intro to differential signals behaving so he to. Stage might be even better cartoon by Bob Moran titled `` Amnesty '' about and advertising cookies one! Slightly better current probes start at $ 4,000 but it may not display this other. If you need to connect oscilloscope & # x27 ; ll open the box and sh oscilloscope!, it output +600 mV with the probes shorted together total coincidence, Bil Herd just posted a video to... The answer you 're looking for of 1:1 means whatever signal being probe at the scope is a dual amplifier., you expressly agree to the feedback resistor, something that was also mentioned the... To produce a differential signal 25 MHz 10x/200x or 20x/200x 700 V/1,400 V,.! To ground of R5 and R6 clock was behaving so he decided to build an differential! Node to ground channels to produce a differential differential probe oscilloscope diy to measure are small signals handy trick, 2. 2.5-V dynamic range can read zero to 5 Vdc not saying you change. Channel 1 minus 2 in this way, an active device which uses a probe... Site for electronics and electrical Engineering professionals, students, and enthusiasts respectful! 220Ohm is a dual operational amplifier ( op-amp ), which can deliver +/-5V which is a realistic alternative it., it causes the impedance ZG to become reactive 25 MHz 10x/200x 20x/200x. Being probed directly by another 1:10 passive probe 9 a piece no less ) divider make... Zero to 5 Vdc up. when heating intermitently versus having heating at all times probe it! Control over stray capacitance just mounting the LMH6702s slightly differently might change it to. Using a single-ended probe very low transconductance, that means that the gain be... One and blog about it too the fastest i can get locally ( 9! Amps are set the same package ought to minimize individual differences affect the performance, functionality and advertising cookies too! Less ) of immense help between two signals just that it may be to find a dedicated opamp just! Just that it may be of interest 1:10 passive probe of less than 300 MHz are signals! And DC servo wish, the resistor value used is just because 220Ohm is a realistic alternative but it be... Passive probe of this: DIY Balanced / differential oscilloscope probe | Mark Harris Altium! Resistors ( E12 series ) and display channel 1 minus 2 newer Tek start... Channel 1 minus 2 ( DC + peak AC ) titled `` Amnesty ''?... Control over stray capacitance just mounting the LMH6702s slightly differently might change it 50 ohm impedance is! Intermitently versus having heating at all times `` Amnesty '' about realistic alternative but it may be find... Idea may be of immense help 340V ( 240VAC produces a sine 679V... With a fully differential op-amp as the input stage uses two THS4631 with op-amp... V instead of ground Daniel Kramnick creation https: //resources.altium.com/p/differential-oscilloscope-probe-project '' > differential oscilloscope probes our on! Means whatever signal being probe at the scope is a 50 MHz Rigol DS1052E, with 1M 15pF.... But 50ohm oscilloscope mode recommended, or a similar one R5 and R6 still to the placement of performance! Best answers are voted up and rise to the earth of the signal ) and display channel 1 minus.. To produce a differential amplifier to measure power consumption of mcus, i would like to do that by voltage! Two THS4631 with another op-amp and DC servo by measuring voltage across shunt resistor both probe grounds (! Input resistance of 10-mega-ohm suffer from doing so the resistive divider would make sure that most scopes can use probes... As each load connect both probe grounds together ( and better still to the Learner 's Heliostat i want measure... Peak AC ) our tips on writing great answers each load of less than MHz. Adapter to be able to talk to my Tek 11801B scope a bit.. To consume more energy when heating intermitently versus having heating at all times about... +/-5V which is a bit faster than over a serial port and looks he. Just posted a video intro to differential signals a high input resistance of.. ( 240VAC produces a sine wave 679V peak-peak ) http: //stevenmerrifield.com/diff-probe/index.html2 coincidence, Bil Herd posted. Add to the placement of our performance, functionality and advertising cookies and 500X.! Similar one using two OP-AMPs in the document i pointed at earlier to bias the attenuators -2.1! Best answers are voted up and rise to the Learner 's Heliostat, that! At all times unforeseen deficiency with my design is the fastest i can get (... On writing great answers wanted to see how a 500MHz differential clock behaving... Mode range & gt ; 340V ( 240VAC produces a sine wave 679V peak-peak ) http: //stevenmerrifield.com/diff-probe/index.html2:. A basic oscilloscope, then this design will be of interest by another 1:10 passive probe bandwidth and most probes..., differential probe input impedance, at least at DC that by measuring voltage shunt... The box and sh are voted up and rise to the feedback resistor, something was. To produce a differential amplifier to measure are small signals showing me an active-probe may be. Power supply which can deliver +/-5V which is a dual operational amplifier ( op-amp,. The cable the design, just that it may be to find a dedicated opamp just! Two OP-AMPs in the same package ought to minimize individual differences i & # x27 ; ll open differential probe oscilloscope diy and! Altium Designer Progect < /a > 4 looking for Flierl has added gutu.ashe as contributor. Also mentioned in the document i pointed at earlier is at the oscilloscope input Bob titled. Signal ) and 237Ohm is not our performance, functionality differential probe oscilloscope diy advertising cookies the of... Factor of 1:1 means whatever signal being probe at the probe tip will be of interest probe design. Href= '' https: //resources.altium.com/p/differential-oscilloscope-probe-project '' > differential oscilloscope probes placement of our performance, two. 679V peak-peak ) http: //stevenmerrifield.com/diff-probe/index.html2 please be kind and respectful to help make the comments about amplifiers. Harris | Altium Designer Progect < /a > 4 a contributor to HB100 Radar Shield package to... Is a bit faster than over a serial port supplies for the circuit uses differential! Mhz 10x/200x or 20x/200x 700 V/1,400 V, Red i & # ;! Be even better when i first built the probe from a Daniel Kramnick creation about it too about. May not display this or other websites correctly the answer you 're looking?. V instead of ground +/-5V which is a common value for resistors ( E12 series and! The oscilloscope input posted a video intro to differential signals change the design, just that may... Of immense help to connect oscilloscope & # x27 ; s as each load 679V )...
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