Why did I make it?

We usually use an oscilloscope for visualizing a voltage over time but sometimes it’s also useful to visualize the current waveform over time. The right way to do it is to get a current probe which can sense the current and convert that to a voltage that the oscilloscope can display however such devices are pretty expensive, they can be around $1000 even for an entry level one like the Rigol RP1001C which is only rated up to 300KHz bandwidth.

On a hobby level we can improvise and use a simple shunt resistor for the same purpose as long as we are aware of it's limitations. But using a single resistor as a shunt has some disadvantages like limited power dissipation capability, limited absolute accuracy as well as increased cost. However by putting several resistors in parallel we can get away with using regular resistors but we get increased power dissipation capability and better absolute accuracy. This is why I designed the ScopeShunt PCB to hold 10 x 1206 SMD resistors thus getting a total theoretical max power dissipation capability of 2.25W. For more information please watch the associated Youtube video where I describe the project in great detail.

What else do you need to build a complete ScopeShunt box as shown in the video?

Besides getting this custom designed PCB you will need the anodized aluminum enclosure, some wiring, a panel mount isolated BNC connector and a couple of 4mm banana sockets. I will place some links below to places where you can get these:

• Extruded Aluminium Project Box 502525mm: Link1.
• Panel Mount Isolated BNC: Link1.
• 4mm Connectors: Link1, Link2.
• Silicone Wires Kit: Link1.

Design features

The PCB was designed as a double sided board with 10x 1206 surface mount resistor footprints and 4 x connection pads for the wiring. The layout has been optimized to separate the sense and the force terminals accordingly. If assembled correctly everything will fit inside the recommended aluminum project box.

Specs

• Theoretical max Pdis = 2.5W (10x 10R 1206).
• Recommended max Pdis = 2.25W.
• Recommended max current = 1.5A.
• Resistance tolerance: better than 1%.
• Max voltage: 24V (due to safety concerns).

Electrical Safety

Care should be taken when constructing your ScopeShunt such as to prevent electrical connection from any of the signals to the metal enclosure. General oscilloscope measurement best practices should also be followed to avoid damage to the equipment.

What you get with your order

You will get 1 x ScopeShunt PCB adapter with or without the resistors assembled depending on your option. The enclosure, connectors, wirings are not included in this order.

Shipping delay & exception notice

Because of the current global situation I will not be able to ship to a list of countries as decided by the postal operators.