Here is a compact power supply for your test bench.
With it, you can finely adjust the voltage (between 0 and 30V) and the current (from 0 to 5A max).
What is the utility of being able to adjust/limit the current?
This is an obvious point for those who know... for others, we will try to explain the utility of a current limitation.
You will then understand that this feature will be "useful" to test more easily, for example, LEDs of power (1W).
Example 1: the LED
The most telling example is the LEDs. When you power a LED, it behaves like a short-circuit... so you have to limit the current so that it doesn't burn. This is why a resistor is placed in series with the LED (to limit the current).
To test different intensity levels of a LED (luminous), simply change the current that passes through it. Basically, you replace the resistance by another value... the current being more or less limited, you will have a different intensity BUT doing so, you also change the voltage across the LED terminals (different resistance = different current = fall of different voltage across resistor terminals).
In short, not easy to see clearly !
The other option, is to fix the voltage and use an active current limiting system. As it is the current which is the predominant parameter in the brightness of a LED, by controlling the current you also control its brightness.
This Lab power supply allows to connect a LED, to fix the voltage and gradually increase the current flowing through it (from a few mA to around ten mA).
You can then study the relation in brightness and the evolution of the current.
This principle of active current limitation is used in the NeoPixel range (each Pixel is equipped with an active current limiting electronics in order to guarantee a homogeneous brightness even when the voltage varies).
Example 2: the continuous motor
Take the example of the continuous motor. A magnetic field being proportional to the voltage, the more the voltage increases the more the magnetic field increases. With a larger magnetic field, the motor is usually more responsive (it reacts faster). This characteristic is mostly used in stepper motors).
So, we have every interest in using a higher voltage on a motor. Except that the current flowing through the motor coils is proportional to the applied voltage.
If your motor is designed for 9V, applying a 12V voltage will make it more responsive (also faster) but the current will also, at this point, be more important than the motor coil will heat up and most likely burn fairly quickly.
The solution is to actively limit the current. You can use higher voltages (ex:12v) without exceeding the maximum current of the motor (the current it would support at 9v, normal operating voltage of the motor). So you get a more responsive motor... without grilling it because the current is limited.
This is the principle used in Stepticks (stepper motor control) used on 3D printers.
- 3-digit display for voltage and current
- Potentiometer setting for voltage and current (multiples turns)
- Input voltage: 200-240V AC 50-60Hz
- Input current: up to 0.9A
- Output voltage: 0-30V Continuous (adjustable)
- Output current: 0-5A
- Accuracy of the output voltage: +/-0.5% (compared to the display)
- Accuracy of the output current: +/-0.5% (compared to the display)
- Yield: >85%
- Regulation under load (10-100%): 50mV
- Nose: 50mV (Ripple noise)
- Current regulation (10-100%): 20mA
- Leakage current: 20mA
- Operating temperature: -10+60C 30-90%RH
- Size: 7 x 16 x 22 cm
- Weight: 2 Kg