Needing a tool on a yearly basis hardly qualifies as necessary, but I had some down time waiting for components and PCBs for another project and began to consider this as an interesting project. The same procedure can be used for current probes of differing current ranges. The maximum voltage the probe will see is 400 VDC. D3 superjunction MOSFET, part number: D3S340N65B-U (V, CREE SiC Schottky Rectifier, part number: C3D04060A, (600 V, 7.5 A). Connect and share knowledge within a single location that is structured and easy to search. It only takes a minute to sign up. He also spent a lot more effort explaining how to assemble the probe and calibrate it. There are also several persons within Hackaday that have completed projects successfully, or are still ongoing. Attach the probes to some HV circuit and then touch one of the unused BNC connectors. This method can be adapted to different probe styles and circuit configurations. Board thickness should be 1.6mm. The base values are 560 + 18 pF, and one or two 12 pF caps can be added. Be aware that it seems that nobody has any LTC6268 (not the -10 version) until sometime in August. Every probe should be low frequency compensated when attached to a scope for the first time. This specification basically states, that any aberration will not exceed +3% or -3% of final value or 5% peak to peak total aberrations. For other applications you may need a different attenuation ratio. Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. did you use a stencil and/or solder paste? I'll be following this with interest. I am too old for small SMD stuff. Probe aberrations should be within the following limits. The diff probe captures the same waveform features as the 10X scope probe. MathJax reference. 02/25/2020 at 15:45, plain - I tried to buy that Hantek 100x probe but they swapped out the order for the P4100. to go to the output, to ground. High Voltage Differential Probes | Tektronix "I don't like it when it is rainy." Because the primary is not an ideal one turn, its final accuracy will be addressed during its final calibration. . How to measure RF power with an oscilloscope? Despite whatever is shown in the schematics, despite R4 actually being a 2M resistor that's soldered on the board, the input impedance of the DSO138 scope is 1 MegOhms (at all ranges, 1V, 0.1V and 10mV). Connect and share knowledge within a single location that is structured and easy to search. Even the coaxial cable connecting the probe to the oscilloscope is difficult, if you give it any significant length. Here are just two examples of things done in modern high performance probes that are pretty hard to replicate at home, unless you buy the parts: Let me show you some google image search hit here again: This is the impedance in Ohm vs. the frequency of the signal for three different probe tip capacitances. You often need a 1000:1 probe. thin and non-conductive, like scotch tape. There are 100x probes with series and shunt R's to solve this problem. Am I just genuinely ignorant of something here, or am I being fed a blob of marketing bamboozlement which is working as intended? Analytical cookies are used to understand how visitors interact with the website. You will need a 5VDC adapter to power Bud's probe or a 7-12VDC adapter to power Paul's probe, and a SMA to BNC pigtail to connect the probe to the scope. Appendix A Use the following equation to calculate the inductance of an inductor with known turns on a known core. It was not very pretty: Its not really bad about -90dB but I was expecting a better result. In a way this is a good thingconsistency is good. When using split rail supply, not a dedicated plus and minus power supply, one should never decouple the op-amps to the GND on the split rain, but they should be decoupled from one power pin to the other, because that is where the return current is going to. My equipment is not up to the task of properly evaluating the performance of the differential probe. Power supply comes either as +/-12 V or as +/-36 V from the AutoProbe interface (some scopes apparently have +/-5 V only). The only oscilloscope I have is a tiny DSO138 (input section is on the top left of page 4 in the linked PDF). Low Cost Arduino Uno Arbitrary Waveform Generator. Login or register to gain full access to the Knowledge+ platform! My hands shake too much to attempt soldering a 0402 capacitor with an iron. The result is approximate because the secondary is not a free-standing inductor, but has coupled loading from the primary. Same channel inputs as above. The scope has a limit of 100Vpp (actually displays only 80Vpp). I did not see a significant reduction in the ringing. Each large spike is me turning off/on the 30V supply. This socket design minimizes ground inductance so that signal integrity is preserved, even a high frequencies. Is that I wish that I had this capability when I was trying to figure out what was wrong with this circuit a few months ago. The ideal core is a Mopermalloy Toroid , a mixture of molybdenum (a non-magnetic gap material) and ferrite. Your mileage may vary.]. So I replaced the OpAmp that creates virtual ground by two low noise linear regulstor (TPS73125 and TPS72325). 30 MHz signals will suffer visible degradation if they feed lengths of coax, unless the coax is terminated. Connected seven 100p caps in series, and connected those parallel to the resistors. MathJax reference. Conformally coat the entire toroid/PCB assembly. The back EMF manifests itself as an additional voltage drop in series with the targets current path,which affects the primary's current flow and thus its accuracy. This calculation is for an elementary inductor (1 winding, 1 core) without any loads reflected from other windings on the core such as within a transformer (>1 winding, 1 core). Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. The simulation results are looking promising, and we'll just test it. A small amount of resistance in series with the probe inputs could remove most of the ringing at the input by reducing the Q of the LC circuit. I want to see the output of a step down transformer. Usually, when confronted with unexpected circuit performance I tend to go back to the simulator and see if I can reproduce the effect and get a handled on the problem. Most solutions can just as easily I thought it was a 1kV probe? sorry i didnt notice this thread got bigger. Are scopes mostly used for seeing waveforms in the 0-10V range? I connected the diff probe positive lead to the top gate signal and the negative lead to the GND of the battery charger. As I am new to this measurement electronics design, i would appreciate any feedback from experienced members. 300 V, CAT III" showing a maximum voltage of 300v at DC - right next to another graph titled ". BTW, these problems are much harder if one seeks to make a probe with The voltage waveform (top) is from a 50 voltage probe and is undistorted. Why is this screw on the wing of DASH-8 Q400 sticking out, is it safe? Use MathJax to format equations. This shield acts as a capacitance to ground for the HV But something is not right. Fit a non-linear model in R with restrictions. I needed a differential probe for BLDC motor ESC development and adapted Bud's design for my needs. DPO/DSA . Cut a length of RG174 (50 ) cable to approximately 5 in. The probe output is showing a pronounced rounded edge instead of a sharp square edge. The RS page claims "Rated voltage 1000V, CAT III (600V CAT IV) (Max.3540 V, CAT I)" - and yet the datasheet makes no claims of it being CAT IV rated whatsoever. Would that mean using an additional 10x passive divider give me grossly innacurate results? I am interested in making my own cheap (somewhat disposable, or permanently attached to prototypes) probes for my oscilloscopes. Oscilloscope Probes | Tektronix The probe as it was designed by Bud and Paul works well and does the job. The above photo is my completed probe. http://how-to.wikia.com/wiki/How_to_make_a_100X_oscilloscope_probe, http://cromwell-intl.com/radio/probes.html, https://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/, Quote from: prawncrackers on April 20, 2016, 03:46:02 am, http://www.ebay.com/itm/P4100-High-Voltage-Oscilloscope-Probe-15cm-2KV-100-1-100MHz-Test-Probe-US-NA0C-/141771437118, Quote from: tautech on April 20, 2016, 09:07:07 am, https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg, Quote from: krivx on April 20, 2016, 09:44:17 am, Quote from: tautech on April 20, 2016, 10:06:12 am, https://www.eevblog.com/forum/projects/oshw-diy-1kv-100mhz-differential-probe-(dilemma-vs-hope)/msg117052/#msg117052, Quote from: krivx on April 20, 2016, 10:15:10 am, Quote from: joeqsmith on April 20, 2016, 05:38:52 pm, Quote from: wraper on April 20, 2016, 06:56:52 pm, https://www.youtube.com/watch?feature=player_detailpage&v=z7rnifjWd_U&list=PLZSS2ajxhiQCAQ6gIp6s-WoKiIEb1gHPD#t=907, Powered by SMFPacks Advanced Attachments Uploader Mod. A 10x probe has a total resistance of 9 meg ohms. Better to connect the string of caps with flexible wires on both ends. I have also included the code for my attempt at that. The rising edge measured by the diff probe. The solution I came up with it to solder some coaxial cable to a BNC connector, and solder the cable directly to the "interesting" trace on the PCB, making a more robust connection (no hooks to detach, very annoying), greatly smaller grounding leads. It's on the order of 5mV (50mV @ 10X), so it is tolerable for this situation. This requires a different power supply on the probe. How about capacitance compensation? now ive thought that at 10x setting the voltage divider within the probe is 9meg in series with the 1meg input of the scope i can make a 100x "mod" if i parallel a 100k ohm resistor with the input impedance (to make 91k). Why doesnt SpaceX sell Raptor engines commercially? [Edit 2020-05-10: Changed C19 to 0.4pF0.05pF to match Paul's schematic. In this concluding part, we'll cover the design and construction of an n:1 voltage probe and a current probe. WARNING.To avoid electric shock, only connect to the This was too low even with the trim cap at the upper end. I do not have any protection in the small probes. created on 01/09/2020 Due to the minimum order quantity I'm going to have a few left over. I do already have an isolation transformer, at least. rev2023.6.5.43477. Should I terminate it? The SMA connector is a bit smaller (6.35 mm wide) than the one on the initial layout (9.5 mm). It depends upon the dielectric constants, board thickness, trace width, and distance between components. The power supply is approximately 2.5V. In LTspice you have use 0.15pF capacitance for 0603 resistors. Why doesnt SpaceX sell Raptor engines commercially? A 12 inch long 26 AWG wire has a self inductance of around 5H. I suggest that you wait until his gerber files are available before ordering PCBs. and last updated a year ago. I'm pretty happy at this point. Transform your product pages with embeddable schematic, simulation, and 3D content modules while providing interactive user The diff probe captures the same waveform features as the 10X scope probe. Probe circuit for measuring higher voltage on oscilloscope? To get into the right trim range, C1C4 had to be set to 9.52 pF (top left). However just having a resistor will result in a poorly behaved probe. If anyone wants a PCB and it's OK with Bud & Paul, shoot me a PM. If you do, you'll get excellent signals at the scope. I would, but it's a bit out of my budget right now. Figure 15 shows how the actual signal appears as it would appear when viewed across a current sense resistor in the same position within the target circuit. I wanted to try a few low cost probes to use with the LeCroy 64Xi and decided to try a few of the Hantek products. So yes, it can probably hit 450V CM before the input is clipped. But if your source has rather small impedance, and the expected frequency range is below few kHz, a simple 90 kOhm to 10 kOhm voltage divider will do the job. What happens if you've already found the item an old map leads to? There are lies, damned lies, statistics - and ADC/DAC specs. Thanks for the tip. ", I want to draw a 3-hyperlink (hyperedge with four nodes) as shown below? By clicking Post Your Answer, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct. Will I need to attach any capacitors? I don't want to put my faith in the undocumented properties of an AliExpress special. Passive voltage probes are available with various attenuation factors - 1X, 10X, and 100X - for different voltage ranges. Meaning don't you get only 25 MHz bandwidth @ 20x gain? I don't want to put my faith in the undocumented properties of an AliExpress special. Turn on the scope and set the Volts/Div. Based on the look-and-feel the quality is definitely on par with the probes delivered with my Rigol DS1054Z, the only complaint is that the ground clamp is fixed. Better to use a safety margin and not go to the limit, especially at lower frequencies. It's also further away from the output OpAmp, so we added the waveguide you can see above. This can be used to supply the probe, auto-detect it, and set the offset. It's not the "primary use" that gets you in trouble, its the other uses. There's an overshoot in the probe's output, which means that the AC gain is too high. I would expect the bridge voltage on a normal power supply to reach as high as 400V. I received their PP-150 probes and they w. Contents 1 Specifications 2 Parts 3 Instructions Putting any sort of capacitance, like the coax or protection would have to be compensated for. The probe construction presented within these two parts are middle of the road designs and are a good starting point for a probe design. You may ask: What data can I trust from a current Probe? The useable (most trustworthy measurements where the distortion-induced error is very small) data is: Wave shapes that have periods comparable to the time constant will be distorted by the time constant. Next step was to select a set of capacitor values that allow to build a probe where. I use mine all the time for repairs and messing about with mains stuff. I'm only just starting to get into oscilloscopes, and from what I've read there are way too many ways to kill a mains-powered scope. You could attempt to make your own probes but with only a scope to work with and it being your first scope, I would not recommend it. AberrationsAberrations are deviations from the final top level of a step function. " You are in emergency mode. But opting out of some of these cookies may affect your browsing experience. Thanks. This edge is faster -- about 10ns -- there is ringing from the probe. On my layout, the capacitance of C6C8 had to be 593 pF (330 + 220 + 33 + 10 pF), which is significantly higher than on Bud's layout. The best answers are voted up and rise to the top, Not the answer you're looking for? Another question: The input opamp TL084 has a bias current of 30pA (max 200pA). 450 ohms for an x10 probe). I just have one small note, that could probably help with your design. Check the power dissipation in the sense resistor: Assemble the sense-end of the cable as in. I created a spreadsheet to calculate a probable range of the capacitance of C1C4, taking into account the tolerance of C6C8: At the bottom, the spreadsheet calculates the resulting attenuation given the values for C1C4 and C6C8 (+trim). (They don't sell probes for this one, so I have to make.). Build your own oscilloscope probes for power measurements (part 2 The signals may be in the MHz range (10-30MHz for example). They are extremely common, and a set of passive probes is usually included with every oscilloscope. Whether this is worth the effort and cost every time is, of course, up to you. By clicking Accept All, you consent to the use of ALL the cookies. Learn More. 01/31/2020 at 16:24, A fellow maker put the diff probe under test, with some serious equipment:https://electronicprojectsforfun.wordpress.com/a-100mhz-differential-probe-from-hackaday-with-keysight-autoprobe-connectivity/.
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