The HW-816 is a buck converter based on the LM2596 regulator from Texas Instruments. It comes with a three-digit 7-segment voltmeter and four buttons.
This buck converter is exceptional in the way its output voltage is set. Rather than using a conventional multi-turn potentiometer, the output voltage can be lowered or raised in small increments of 0.02V/0.1V by two push buttons.
The board is occasionally available for under EUR 3.00 in which case it serves very well as a cheap and small versatile mini bench power supply.
By soldering wires to the push buttons, the output voltage decrement and increment functionality can easily be controlled by microcontroller GPIOs, additionally enhancing the versatility of this board. In combination with a voltage sensing shunt, the board can be an excellent choice for digitally controllable constant voltage power sources of up to 3A.
This is a Constant Voltage (CV)-only Buck converter. It cannot supply a constant current (CC) and is therefore unsuitable for charging batteries.
| Property | Value |
|---|---|
| Input Voltage | 7-36V |
| Output Voltage | 0.5-35V |
| Max Output Current | 3A (>2A add heat sink) |
| Size | 56x41x13mm |
| LED | 2 (IN and OUT, indicating the voltage the voltmeter is showing) |
| Voltmeter | 3-digit, input or output voltage, can be turned off |
For output currents >2A, an additional heat sink and/or fan is required.
Measuring Input/Output Voltage
The board comes with four push buttons, two on each side of the display. The two lower buttons on each side are marked IN/OUT and ON/OFF:
- IN/OUT: Toggles the voltmeter to display either the input voltage or the output voltage. The currently selected mode is shown by the LEDs IN and OUT.
- ON/OFF: When short-pressed, turns the voltmeter on and off. When long-pressed, turns the output voltage terminal on and off. When turning the output voltage off by a long-press without a load connected, it may take a few seconds for the output voltage to drop to 0V.
Adjusting Output Voltage
This is a buck converter: the output voltage is always lower than the input voltage. The maximum output voltage is about 1-2V below the input voltage.
The output voltage is set with the two buttons at the rim of the board, marked + and -.
For output voltages below 10V, the increment and decrement is 0.02V per key press. For higher voltages, it is 0.1v.
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(content created Apr 11, 2024)