After the soldering iron, an adjustable laboratory power supply is the most important maker utensil: We took a closer look at a fairly fresh example.
You can spend 40, but also 4000 euros for an adjustable laboratory power supply – the price range is just as large as the range of features offered. Anyone who, as a maker, has to supply thick motors or power output stages, can now also find inexpensive devices with considerable performance, which are extremely compact and light thanks to switching controller technology.
Two devices from the Chinese manufacturer Kiprim, which sells its products on Amazon, are quite recent representatives of this guild. Two versions are available: The DC310S with 30V and 10A for around 130 euros and the slightly more expensive DC605S with 60V and 5A at around 170 euros. We took a closer look at the latter.
First of all, the low weight of a good 1.5 kg for a 300W power supply unit, the narrow, compact design and the TFT graphic display instead of the seven-segment displays that are otherwise usual in this price range are surprising. Unfortunately, the limited space on the front panel means that operation via buttons and rotary encoders is rather cumbersome. Older makers will hardly be able to reliably set the tiny preset values without reading glasses. The digits selected for change are very small and are only faintly highlighted in color. The latter also applies to the list of setting presets.
The display can be switched to show a history of voltages and currents in the form of a (slowly plotting) oscillogram – great for observing trends in current draw, which is tedious on a numeric display. The currently delivered power is also displayed. A USB charging socket provides an additional 5V at a maximum of 1A.
Nothing surprising about the regulation: With a load change from zero to 1A and 10V output voltage, this changes by about 20mV (measured directly at the terminals), a quite useful value. The load regulation takes about 4ms, the overshoot at load shedding is about 50mV. With an initial output voltage of 10V, the current control needs about 30ms to react to overload; this is far too long for testing components (e.g. LEDs). Like the leisurely load regulation, this is due to the switched-mode power supply principle.
High-frequency residues on the output voltage in the range of 200 kHz are more disruptive here, which can easily reach an amplitude of a few hundred millivolts at higher currents (see oscillogram). This becomes a problem when you want to supply radios, two-way radios, high-quality audio electronics or sensitive measuring devices. All other applications should be able to handle it, the money is then well invested. After all, the device can also be remotely controlled via USB, with the included software, for example, the charging characteristic of a battery can be recorded, or you can program a time-controlled sequence of output voltage and current.
