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Tektronix THS7xxx Scope Hack/Teardown/Discussion - FW 1.16 found
lor3n7o:
the p5102 is a probe exclusively dedicated to the ths700.
If my theory is correct it can only work on oscilloscopes with isolated channels such as the THS 700. It cannot be used on oscilloscopes with grounded ref, or with ref shared between channels.
In the datasheet of the wave the p5102 is defined as floating probe for THS700.
I am attaching a datasheet of the probe where it is illustrated.
giacomo:
You are right :-+ i was supposed to fully RTFM first
You can still use other types of probes unless you have a specific requirement
We know that the input resistance of the scope is 1M, the probe is a 10:1 divider, assuming that we are measuring at DC it might be 9M distributed equaly between the two sides like 4.5M resistors plus another 10M resistor from the tip of the probe to ground, this would be a possible configuration in order that the scope plus the probe attached will be seen from the circuit like a 5M resistor at DC
Similar for the capacitance, the capacitance seen from the load should be 11.2pF, the result of the parallel between a capacitance from the tip to ground and the series capacitance of the scope plus another capacitance in order to form a 10:1 divider. The capacitance of the scope is 25pF, we need a 9x larger reactance, hence a 9x smaller capacitance, 2.8pF, 1.4pf in parallel with each 4.5M resistor. 11.2pF minus 2.8pF in series with 25pF = 8.7pF (adjustable) across the 10M resistor
It might be more appropriate to open another topic about probes.
harrimansat:
Which is tHe max working voltage between BNC GND, 30V?
lor3n7o:
--- Quote from: harrimansat on March 17, 2021, 09:55:35 am ---Which is tHe max working voltage between BNC GND, 30V?
--- End quote ---
I assume 60V.
30V + 30V.
30V between each BNC-GND to internal scope GND.
30V when using a common probe or standard P6117.
When using the P5102 this value rises to 600V.
lor3n7o:
--- Quote from: giacomo on March 17, 2021, 12:23:23 am ---You are right :-+ i was supposed to fully RTFM first
You can still use other types of probes unless you have a specific requirement
We know that the input resistance of the scope is 1M, the probe is a 10:1 divider, assuming that we are measuring at DC it might be 9M distributed equaly between the two sides like 4.5M resistors plus another 10M resistor from the tip of the probe to ground, this would be a possible configuration in order that the scope plus the probe attached will be seen from the circuit like a 5M resistor at DC
Similar for the capacitance, the capacitance seen from the load should be 11.2pF, the result of the parallel between a capacitance from the tip to ground and the series capacitance of the scope plus another capacitance in order to form a 10:1 divider. The capacitance of the scope is 25pF, we need a 9x larger reactance, hence a 9x smaller capacitance, 2.8pF, 1.4pf in parallel with each 4.5M resistor. 11.2pF minus 2.8pF in series with 25pF = 8.7pF (adjustable) across the 10M resistor
It might be more appropriate to open another topic about probes.
--- End quote ---
yes, I also assumed there could be a configuration like this in the probe. the only difference I thought is that the capacities in parallel to the 4M5 resistors are 5.5pf and not 1.4pf.
I believe the correct value is 5.5. to get the series 25pf-5.5pF-5.5pF = 2.48pF which in parallel with 8.7pf // 2.48 = 11.2pf.
Can this be correct?
It would be curious if someone who has a P5102 probe could check if there really is this resistance between probe ground and BNC ground.
Do you think it is better to open another post?
or we continue to talk here since we always talk about the ths700?
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