The Micsig CP503B clamp-on current probe, DC to 50 MHz with 5 A and 30 A ranges: its specifications, what owners report, and how we will use it to check current readings on Rigol scopes running NovaOS.
| Bandwidth | 50MHzData sheet, p. 4 |
| Rise time | ≤ 7nsData sheet, p. 4 |
| Max. current input | 30Arms, 50ApkData sheet, p. 4 |
| Range | 5Arms (5A), 30Arms (30A)Data sheet, p. 4 |
| Accuracy (max continuous current @ DC and 45-66Hz) | ±1% ±1mA (5A), ±1% ±10mA (30A)Data sheet, p. 4 |
| Lowest measurable current | 1mA (5A), 10mA (30A)Data sheet, p. 4 |
| Noise (20 MHz limitation) | <4mApp (5A), <30mApp (30A)Data sheet, p. 4 |
| Output sensitivity | 1V / 1A (5A, 1X), 1V / 10A (30A, 10X)Data sheet, p. 4 |
| Power supply | DC 12VData sheet, p. 4 |
| Max. conductor diameter | 5mmData sheet, p. 4 |
| Cable length | 1mData sheet, p. 4 |
| Interface | Standard BNC InterfaceData sheet, p. 4 |
Micsig's own figures, as its documents state them; each links to the page it is on.
This is the current CP503B, with 5 A and 30 A ranges and a 12 V adapter. An older version, with 6 A and 30 A ranges and a USB power adapter, is still sold under the same number: check the range buttons and the adapter in the listing before you buy.
Clamps around a wire and turns the current flowing in it into a voltage a scope can show.
Checks that a scope channel set for a current probe reads in amps, end to end, against a known current from the bench load and supply.
On a Rigol DHO800/900 or MHO900 running NovaOS, a channel can be set to amperes and the probe's sensitivity typed in mV/A or V/A on the channel's sheet: the CP503B's 1 V/A is 1x and its 0.1 V/A is 10x. The trace, the measurements and the cursors then read in amps. The probe checks that end to end, clamped on a lead carrying a known current from the bench's power supply into the electronic load.
The tests we will run with it when it arrives; the results will appear here.
Owners find its DC accuracy and its noise good, but its gain is not flat above about 1 MHz: the datasheet's frequency response is more optimistic than their Bode plots. Power it from its own adapter: run from a scope's USB port, one owner saw a 3 V offset and a flashing range button. When the current comes from an electronic load, the load's control loop shows up as ripple; run the load in constant-current mode, or use a power resistor instead. The newer 5 A / 30 A version is reported to have lower noise, with the same response above 1 MHz.
From EEVblog forum: Micsig CP1003/CP503 100MHz/50MHz Current Probe.
Forum threads worth reading before you buy one.
Back to the bench: everything NovaOS is developed and measured with.