HFX – Electrical Test Set


Hui Gardens HFX electrical test set is the fusion of several basic electrical things that I’ve built while making other electronic things. It combines my HF1 – 100W Resistor Box, HF11 – 2 Wire RTD Simulator, the most useful parts of the HF2 -24V Variable DC Power Supply and more! I decommissioned the mentioned prototypes and repurposed almost all the parts including wires and resistors.

The Hui Gardens HFX features the following:

  • 24V adjustable DC power supply from 4x AA batteries (easy access) to loop power 4-20mA transmitters
  • 100W resistors including a 270Ω (close enough to a 250Ω resistor) for HART communication
  • 10 turn 2W potentiometers to allow for RTD simulation and 4-20mA simulation
  • 10W shunt to allow for high current measurement
  • Relay to take input and switch loads on and off and allow triggering of a frequency counter to test timing
  • 0.75″ spacing standard between banana jacks for double banana leads

I wanted something that can carry my Fluke 87V multimeter and be useful for things I test on a regular basis. I took a design cue from some of the high voltage equipment I see that allows for the meter and test leads to be stored in one case. Having a separate lead bag is really cumbersome and is prone to getting lost. I really like the brass wingnut chassis ground aesthetic. If it’s good enough for a 120kV hipot, it’s good enough for me!

Housed inside a Nanuk 920 hard case with a cut aluminum panel kit, the Hui Gardens HFX is pretty tough. The big red toggle switch cover is a must, the Chairman Mao emblem is an especially nice touch, but the best part is the custom 3d printed nameplate in brass.

HF11 – 2 Wire RTD Simulator for PT1000


Hui Gardens HF11 2 wire RTD simulator for PT1000 was made to be used as a calibration standard for the Hui Gardens HF3 WiFi RTD Meat Smoker Temperature Transmitter. Coarse (10kΩ) and fine (1kΩ) adjustment via 10 turn potentiometers allow precise setting of resistance value. Since there are no graduated steppings like a traditional decade box, it does not require calibration and is as accurate as the multimeter being used to characterize it.

The banana plug connectors are spaced such that the fancy two conductor leads can be used. Connect the two sets of banana plug connectors to use them together or disconnect to use separately.


This working prototype had been superceded by the Hui Gardens HFX electrical test set

HF1 – 100W Resistor Box


Hui Gardens HF1 100W resistor box prototype was created to provide a dummy load when testing electronics. It features an aluminum enclosure that also acts as a heat sink. Banana jack connector inputs were chosen for durability during transport and also to maintain a low profile. Just toss this rugged resistance standard into your Pelican case.

Due to the experimental nature of this decade box, each resistor is connected to its own banana jack connectors via blade connectors for easy replacement of individual resistors should they burn out.

Specification Value
Maximum Power Dissipation 100W
Maximum Voltage 1900V
Resistor Tolerance 5%
Resistor Values 0.1Ω, 1Ω, 10Ω, 100Ω, 1000Ω


This working prototype had been superceded by the Hui Gardens HFX electrical test set