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Questions tagged [probe]

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13
votes
3answers
1k views

Why are oscilloscope input impedances so low?

My question is two-fold: Where does the input impedance come from? I'm wondering where the input impedance of your average multimeter or oscilloscope comes from? Is it just the input impedance to ...
19
votes
5answers
4k views

CRT Oscilloscope - part of the plot is missing

I picked up an old METRIX OX 720 oscilloscope. I replaced 2 capacitors that went up in smoke. Once restarted, here is the signal I get. The vertical part of the signal is missing. It is the same ...
1
vote
0answers
66 views

Build a high voltage probe to calibrate a 1.5 kV oscilloscope CRT supply voltage

I want to build a high voltage probe to calibrate my 1.5 kV oscilloscope CRT supply voltage. Will just use this probe once to calibrate the scope so I don’t want to spend $200 on a probe and I mind ...
0
votes
3answers
87 views

AD620 pH probe has a positive voltage offset!

I am a chem eng. but little background in electronics. I'd like to interface a pH probe with an AD620A, the original PCB that came with pH probe was damaged by a current leak in the solution. I made ...
0
votes
1answer
163 views

Adding a second Y axis to an LTSpice plot

I am new to using LTSpice and am coming over from using Cadence. In Cadence you can add a second Y axis. Plot-> Add Y Axis is the probe pane in Cadence. Is there a way to do this in LTSpice?
1
vote
2answers
75 views

Oscilloscope probe pF values

I bought some time ago a 2nd hand Philips PM 3253 including probes which shows on the oscilloscope probe inputs: 1 MOhm, 20 pF While the probes I got with it ...
0
votes
2answers
179 views

Is this type of scope probe homemade? [duplicate]

To reduce the loop area and noisepick up, the GND lead of the scope probe is very next to the tip in the below probe: I don’t have such probes and my scope probe GND leads are much longer alligator ...
1
vote
0answers
44 views

Schematic diagram probe question

I am not sure whether to call it a probe on my schematic diagram or is it something else. I have ATmega328P checking its two digital pins whether both have been connected to the ground. When floating,...
0
votes
0answers
93 views

TMC2130 IC only working when being probed

I designed a small shield for a Wemos D1 mini and a TMC2130 SilentStepStick. After the ESP boots up, it is supposed to initialize the TMC2130 via SPI to move a stepper motor afterwards. My problem is ...
0
votes
1answer
107 views

Oscilloscope Probe - How to measure a sensitive circuit

Help needed in measuring a tiny piezo actuator. The circuit bangs the actuator with a voltage ( max 50V ), then senses the ripples after the initial actuation. How can I measure with an oscilloscope ...
1
vote
2answers
122 views

Can I use any HV Probe for a Voltmeter/Ampmeter gauge?

I purchased the multimeter pictured below for a high voltage power supply I'm working on. It's rated for 100V DC and 10A, but I hope to measure several thousand volts. Is it possible to use a HV ...
2
votes
1answer
79 views

What effect does a logic analyzer probe have on a circuit?

I have an MCU controlling a LED sign. This sign speaks the HUB75 protocol, which is essentially a large shift register. Being a shift register, this requires a clock signal to be generated, which the ...
1
vote
3answers
126 views

Adding Debug LEDs to PCB

I'm working on the next revision of a prototype PCB board, and from the first one I learned that LEDs would be very helpful instead of having to probe each pin/wire for a certain state. In this ...
0
votes
2answers
77 views

Can you receive a shock by touching only one probe ?

in this video at 4min 4sec https://youtu.be/CkGVMWK10qU?t=243 The guy receive a shock of a taser by touching a metal object that touches one probe, but why does the arc goes through his body ? I know ...
8
votes
3answers
921 views

How the low inductance of short ground clip probes prevents interference?

Below are photos of two scope probes with different ground clip lengths: I have read that the shorter ground is used to minimize the inductance of the probe ground lead. But what does that help for? ...
4
votes
2answers
212 views

Oscilloscope: when to use coaxial instead of probes?

I understand the difference between passive and active probes, and between x1, x10, x100, ... I also understand that at high frequencies the capacitance of the oscilloscope has to be considered, so a ...
9
votes
3answers
2k views

Does this experiment show that Kirchhoff's Law hold when there's a changing magnetic field involved in a circuit?

In this video, the electrical engineer and youtuber Mehdi Sadaghdar (ElectroBOOM) disagrees with another video from professor Walter Lewin. Basically, professor Lewin shows in an experiment that if ...
3
votes
1answer
187 views

What is the proper name for this oscilloscope probe accessory?

These used to come standard in the accessory pack that comes with a new o'scope probe, but they haven't been included in quite some time. They are very useful for checking certain test points, and we ...
1
vote
1answer
51 views

FLUKE 15b+ fuse test

I have accidentally shorted my circuit (5 Volt Vcc) for approximately 1-2 seconds max. While the circuit was short circuit I use the FLUKE as ampermeter in miliAmper mode (400mA max fused) The current ...
1
vote
2answers
175 views

How do current probes load a circuit?

It's usual to talk about loading a circuit when measuring voltage, with a voltmeter or with a voltage probe and an oscilloscope. It can be seen as putting an impedance in parallel to the element whose ...
2
votes
1answer
104 views

Segger ATSAME54N20 SWD error

INTRODUCTION I'm trying to program a custom board I designed, featuring a SAME54N20 MCU. My programming probe is a J-Link EDU (version 10.1), connected to my board using a Olimex adapter with a 10 ...
0
votes
0answers
30 views

Can I use a scope probe to connect a signal generator to a generic circuit?

It's an exam question stated as in the title. I don't know how to analize the problem. As long as it's a BNC to BNC coaxial cable anything goes I think, but I don't know for attenuating probe or ...
3
votes
1answer
277 views

How does capacitive coupling work for measurements

The context is the measurement of engine speed on a vintage car that uses a classic Kettering ignition system. Essentially, a voltage pulse of tenths of kV is generated on a high tension (HT) lead. ...
0
votes
2answers
666 views

Measuring differential signal with single ended probe

I have a differential signal(a +/- signal) to measure. Can I use a single ended probe to measure it and then just multiply whatever I read by 2 to get the actual amplitude?
0
votes
1answer
106 views

Oscilloscope differential measurement for battery powered circuit using single probe

I want to measure the voltage across a resistor in my circuit. The circuit is battery powered. I don't want to use the two probe method and calculate A-B to get the results. Can I use one probe to ...
7
votes
1answer
894 views

Why is an oscilloscope's Attenuation switch placed on the probe?

I'm wondering why an oscilloscope's Attenuation switch is placed on the probe not on the oscilloscope's body (like the AC/DC Coupling switch that's placed on the scope body not on the probe)?
0
votes
1answer
54 views

Why is the logic probe reducing current from the power supply?

I am troubleshooting a very basic circuit using an inexpensive logic probe to check values. Typically when I use the probe I see current output go up about 7mA, which I assume is to power the sound ...
3
votes
2answers
798 views

Why am I getting a half-wave rectified output when i am using a full-wave rectifier?

I have recently gotten back into electronics and have access to a lab with a signal generator and oscilloscope. I have been trying to teach myself how to use this equipment by building small and ...
0
votes
2answers
108 views

Probes gives different results

I discovered an "funny" thing today. I had used a GW instek probe GTP-150B-4 150Mhz in 10x mode and documented the result. Today I noticed in the testing department that what I've measured doesn't ...
1
vote
2answers
701 views

Probe circuit for measuring higher voltage on oscilloscope?

The only oscilloscope I have is a tiny DSO138 (input section is on the top left of page 4 in the linked PDF). The scope has a limit of 100Vpp (actually displays only 80Vpp). At the highest attenuation ...
0
votes
1answer
54 views

i2c probe happens only alternatively

I have connected a NXP NFC Module (pn7120) over I2C to i.MX6 Board. I tried to check whether the device is detected in the i2c probe command. It didn't detect in the first call, but got detected in ...
1
vote
3answers
122 views

HF signal in a null experiment. What is the exact mechanism?

Since I've tried to experiment with electronics, I am faced with the problem of HF noise and signals bypassing almost anything I try to stop them. This begun with my attempts to filter the noise of a ...
16
votes
2answers
3k views

Review request: DIY DC to 50MHz differential oscilloscope probe

Given the cost of proper differential probes, i've decided to make my own. The requirements are: DC to 50 MHz 3db bandwidth A few selectable input voltage ranges, from 3V pk-pk to 300 V pk-pk ...
0
votes
2answers
104 views

The probe and Oscilloscope selections for measurement

*I searched about the correct oscilloscope and probe to measure the a signal with a certain frequency. I read some documents and white papers about this topic. I have heard some "rule of thumbs" about ...
12
votes
3answers
1k views

High speed passive probe - contradiction between authors or different points of view?

In a document Hiscocks et al. describes some basics of Oscilloscope probe theory. The document is very understandable and seems coherent. Notice in particular that for him, the bad guy is the parallel ...
1
vote
1answer
92 views

Passive probe vs diffential probe

In the image: Channel 1: Drain to source voltage Channel 2: gate to source voltage Channel 3: Switch current Channel 4: Load current The image shows Vds of low side MOSFET at turn on measured with a ...
4
votes
1answer
292 views

Why modern oscilloscopes inputs are not fully differential (i.e. floating)?

This question is somewhat related to this other EE.SE question, and some hints are given there, but are not completely satisfactory for me. I've understood that, besides safety considerations, the ...
0
votes
2answers
431 views

How to make a symmetrical DC power source?

I have been tasked with creating a logic probe that reads High/Low/High Impedance, but what works in simulations, isn't working in practice. This was my idea: I made a symmetrical power source using ...
11
votes
7answers
2k views

Good uses for 1:1 probe

We all know why using a properly compensated 10:1 probe is a must when viewing MHz-speed signals on a scope with a 1 MOhm input impedance. Now who can supply a good use for a 1:1 probe? These probes ...
2
votes
1answer
274 views

Scope voltage drop across a 7R5 resistor

I am currently measuring the current draw of a PCB and have managed to get down into the uA range. I am able to read 8uA when I use my TENMA 72-7780 as a current sensor. However when I use a 7R5 ...
0
votes
4answers
250 views

Small ICs pitch and Oscilloscope probing

I have a STM32L432KS circuit with this 0.5mm pitch UFQFPN32 package: I have to take a look at some pads but with which kind of oscilloscope probe could I use?
0
votes
2answers
158 views

Current Probe on CRO?

Is it possible to measure waveform of current with current probe connected to analog oscilloscope? Or is that possible only with digital oscilloscope? Are there any other instruments out there that ...
0
votes
1answer
545 views

AC RMS current measurements with oscilloscope

I am going to measure the AC current(three phases), with a current probe, of a large machine, with an oscilloscope. The scope I am using has the following two options: RMS: RMS (Root Mean Square) ...
0
votes
3answers
135 views

Questions about differential probes

(Q1) Can an active differential probe such as this Agilent N2752A be used in a single-ended way, i.e., with one of its inputs at the GND of a circuit? Understanding of course, that we have (a) 1/...
0
votes
1answer
234 views

Why doesn't a passive x1000 oscilloscope probe have 1000M Ohm impedance?

Most of the x1000 high-voltage oscilloscope probes I find seem to have input impedance around 100M Ohm. For example the P6015A from Tektronix (100M Ohm) or the PPE6KV from LeCroy (50M Ohm) or these ...
1
vote
1answer
195 views

Why is the calibration signal's amplitude of my oscilloscope 10 times higher than stated?

I'm trying to calibrate my HAMEG HM507 oscilloscope. The manual says that the calibration signal is 0.2Vpp. With the attentuation of the probe set to x10, volts/division set to 5mV/cm, time/division ...
0
votes
1answer
108 views

Can a probe with readout actuator be used on a scope without readout feature?

Some oscilloscopes can detect the attenuation set on the probes in use ("readout"), if the probes have the corresponding protruding activator pin. The probes are mostly offered with or without this ...
3
votes
1answer
95 views

Distance between 3d voltage probes

I am making bipolar voltage measurements in which the distance between my probes small enough that I think the geometry of the probe contact tips is non-trivial. As illustrated below, my voltage ...
0
votes
2answers
120 views

Not sure if this circuit will work, did I overlook anything?

I plan to purchase a DS18b20 water temperature probe, and hook up the data line to an arduino. I would then connect the arduino to ten 5VDC 6A relays , and each relay would be connected to a 120VAC ...
2
votes
2answers
770 views

Digital temperature meter probe wire length

I bought a cheap Chinese digital thermometer like this one with this description Link to product Item specifics ...