Posted Fri, 16 Dec 2022 19:37:48 GMT by Honc, Randy Uknown
i need a compensation circuit to connect the following probe to a mso3004
the waveform observed is around 120 Hz
the probe is a Hantek HT25
see attachment

Thank you in advance for your help
Posted Mon, 19 Dec 2022 21:17:30 GMT by Teles, Afonso
Hi Randy,

Information online about the Hantek HT25 is limited, but it appears to be an induction/current probe specialized for automotive use.
This type of probe features a different circuit from the one featured in your image (which is more of a passive voltage probe circuit).

With the information I have, I cannot help you with creating a compensation circuit, I would need to know more about the inner workings of the probe or, at least, what impedance it expects to be terminated into.
I would suggest contacting Hantek.
Posted Mon, 19 Dec 2022 22:13:12 GMT by Honc, Randy Uknown
it is a passive circuit, there is no power/excitation applied to the probe.

i want to input to a tek scope 1Mohm, 13pF

can you make a compensation circuit for the attached pdf

Posted Tue, 20 Dec 2022 18:27:28 GMT by Teles, Afonso
Hi Randy,

To make a compensation circuit I would need to know what termination the probe expects, which isn't specified by the manufacturer.

From the images you sent me, this probe seems to be little more than a coax cable with connection points at both ends. The capacitance you measured is a normal characteristic of coax lines, it does not represent a capacitance that needs to be compensated for.
It is essentially working like a 1x passive probe. These do not require compensation, although they may require matching if their characteristic impedance is different from that of other parts of the system (usually 50 or 75 ohms). This characteristic impedance is also not specified by the manufacturer, as far as I can tell, but it is probably 50 ohms.

I will also note that this probe, if used in a spark plug circuit, could supersede the maximum rated voltage of the oscilloscope.

I would suggest contacting Hantek about the above mentioned points.
Posted Wed, 21 Dec 2022 23:14:29 GMT by Honc, Randy Uknown

Hantek HT25 Auto Ignition Probe

The HT25 Auto-Probe is a type of inductive capacitance probe, intended for use with an oscilloscope. Its purpose is to help diagnose engine ignition problems. It works by displaying a waveform corresponding to voltage against time for a cylinder parade.

The capacitive sensor is designed to measure the voltage that is generated in the secondary forces the ignition coil (transformer). The sensor adjusts the signal for optimal display on the screen of the ignition process of a digital oscilloscope. Tongs are sturdy and durable construction, earth clamp jaw is large enough to easily fit in the engine compartment and the overall ergonomics underscores the long cable length 2.5 m

Attenuation sensor is 1000:1, that means 1V displayed on the oscilloscope grid represents the secondary 1kV

Auto ignition probe HT-25 can be used with most oscilloscopes and motor testers from other manufacturers assuming, that oscilloscope has invert display function and attenuation setting to value 1000:1 or 10000:1.

Auto ignition probe HT-25

Auto ignition probe HT-25 HT -25 are designed to measure high voltage the output of the ignition coils respectively of the secondary winding or secondary or power output ( for high-voltage diode) . capacitive sensor can be be used to capture high voltage waveforms, both conventional distributor ignition systems and on systems without distributor (DIS ) - the fully electronic ignition systems . For the diagnosis of the secondary coil on plug systems (EFS / COP ) is necessary use extension adapter coil on plug. 

Use the diagnosis

Given the very high voltage (up to 40kV ) that for secondary circuit typically not possible perform measurements directly connecting the output of the coil, as is the case with measurement of primary. Trying to such measurement could seriously endanger health technology and certainly would lead to the destruction of oscilloscope and computer. to measure Therefore, secondary use capacity and inductive sensor. involvement pliers is simple. First of all involved ground clamp pliers the motor housing , then clipped with pliers Spark cable , or the extension adapter, connector clamp connects the BNC oscilloscope input , start the engine and measure can begin. Pliers features used to measure the ignition on one cylinder , for a test to secondary four-cylinder engine , it is necessary 4 used pliers and possibly 4connection adapters. 

Examples of use - Ignition systems:

  • conventional spark systems (with distributor) 
  • CIC (Coil in Cap) as GM HEI, Toyota, Honda, Nippondenso etc.
  • DIS (no distributor) fully electronic ignition. With the extension, also EFS / COP

Control Program HANTEK 3064 / A and 1008C are pre-measurement for very precise diagnosis of the secondary. In the preset measurement is integrated into the formula to calculate the values spark voltage (needle) voltage discharge at spark, burning time and duration inductive.

Posted Wed, 21 Dec 2022 23:34:52 GMT by Honc, Randy Uknown
pg 104 list specs for the dso 3064

is there an channel invert on a mso 3034
if i want to invert the waveform on a mso 3004 do i need to display a math function (CH1 * -1)

Posted Wed, 21 Dec 2022 23:48:45 GMT by Honc, Randy Uknown
mso 3034 pic
Posted Wed, 21 Dec 2022 23:56:02 GMT by Honc, Randy Uknown
so the questions are

1 do i need a compensation circuit
2 is there an invert function or use math
3 is maximum rated voltage for both scope comparable

Posted Wed, 28 Dec 2022 22:00:48 GMT by Teles, Afonso
1) A compensation circuit might be required, but to design one we would need to know what load the probe expects, which is not defined anywhere by the manufacturer.
The probe is still usable with a mismatched load, it just won't be viable for accurate measurements.

2) Yes, the MSO3034 is able to invert input signals, the procedure is described on page 90 of the manual:

3) You posted three scopes, a TDS3000 which has a max input in 1M of 150 Vrms CAT I, an MSO3034 which has a max input of 300 Vrms CATII in 1M mode.
The DSO3064 manual you posted does not appear to be for one of our products and I could not find its input voltage rating listed.

Additionally, from the measurements you took of the probe, it appears to me that the input and output of the probe are shorted, which I do not believe would lead to the 1000:1 attenuation claimed by the manufacturer. This might be because it is damaged and needs repair before use.
I would suggest contacting the probe manufacturer about this and other questions about the probe.

You must be signed in to post in this forum.