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For about € 7.00 you buy this small power supply. The output voltage is adjustable between 9 Vdc and 24 Vdc at a maximum current of 1 A. Ideal for feeding small circuits, DC motors and fans. |
Introduction to the JDT2410
A small plastic housing of 9 cm x 5 cm x 4 cm
The power supply is hidden in a small black plastic housing that you can easily include by hand. However, at least according to the specifications, this device must be able to supply a DC voltage of at least 9 V and a maximum of 24 V at a maximum current of 1 A. The maximum power supplied is therefore 24 W. At the top, the 110 cm long 110/230 V cable is attached to the box. At the bottom is the output cable with an identical length and with a standard 5.5 mm x 2.5 mm connector with the plus in the middle. The mains cable is equipped with an American plug. Some suppliers supply an adapter plug to the European standard. The potentiometer is equipped with an ON/OFF switch. When you switch on the power supply, a blue LED lights up, which flashes if you overload the power supply. The voltage then drops to a few volts.
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| The adjustable stabilized power supply JDT2410. (© Banggood) |
The manufacturer provides the following specifications:
- Working principle: PWM, pulse width modulation
- Input voltage: 110 Vac ~ 240 Vac
- Output voltage: 9.0 Vdc ~ 24.0 Vdc
- Output current: 1.0 A max.
- Protection: against currents greater than 1.5 A
- Dimensions: 86 mm x 48 mm x 30 mm
The electronics of the JDT2410
The housing consists of two parts, you can click them together but never click them apart again. Fortunately, a fine iron saw brings a solution. By sawing in the gap between the two parts you can still take the cabinet apart. The PCB in the housing is shown in the picture below. All visible components are of excellent quality.
You will recognize the standard image of such power supplies. On the right is the power section with the bridge rectifier, the primary smoothing capacitor and the PWM chip under the cooling plate. On the left the power transformer and the secondary rectifier and smoothing capacitor. Above the transformer you see the optocoupler U2, which provides galvanically separated feedback from the secondary to the primary side and thus also stabilizes the output voltage.
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| The PCB of the JDT2410. (© 2018 Jos Verstraten) |
Testing the JDT2410
Voltage range at the output
The tested JDT2410 delivers an unloaded output voltage of 8.26 V to 24.8 V.
Load table at 24.8 V
In the table below we have given the relationship between the maximum output voltage and the load current. With a current of 1.5 A, the power supply turns off after a few seconds and the LED flashes. Over the specified current range to 1 A, the output voltage drops by 0.3 V. From this, you can calculate the internal resistance as 0.3 Ω.
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| The load table at maximum output voltage. (© 2018 Jos Verstraten) |
The oscillogram below shows the noise and ripple at the output voltage of 24.8 V at a current of 1 A.
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| The noise and ripple at maximum output voltage and maximum current. (© 2018 Jos Verstraten) |
Of course we repeated our measurements at the minimum output voltage. The results are shown in the table below. From the voltage drop of 0.31 V, an internal resistance of 0.31 Ω can be derived.
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| The load table at minimum output voltage. (© 2018 Jos Verstraten) |
In the oscillogram below you can see the noise and ripple at the output voltage of 8.26 V at a current of 1 A.
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| The noise and ripple at minimum output voltage and maximum current. (© 2018 Jos Verstraten) |
General conclusion
If you need an adjustable DC voltage, this is an ideal power supply. The circuit does what was promised. Undoubtedly, the output resistance would be even smaller than 0.3 Ω if the manufacturer had provided the output cable with slightly thicker copper wires. A very good product for a very acceptable price!
9V-24V 1A 24W Power Supply
