Banggood DIY LM317 Adjustable Voltage Power Supply Board Kit

Created: January 29, 2018


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Youtube Link to: Banggood sku 187857 Power Supply Review

Getting more out of this little power supply:
The extra components that the manufacturer put onto this board soak up some of the power available from the LM317's output.
Others have simply left those components off the board.
I chose to build the kit exactly as designed. But later, I decided to make the extra components switchable.
All I had to do was to add a switch to turn the power to the Hex Inverter on and off,
After doing that, I retested the output of the power supply with and without the Hex Inverter Chip and the LED's that are connected to it.
A link to those test results can be found at the bottom of this page.

Here's what I did:
The schematic at the Banggood website for this power supply is incomplete.
It shows the active elements, but not all of the power wiring. I had to follow the PCB traces to figure it out.
I cut the trace between the regulated output of the LM317 close to the Vcc connection (Pin 14) to the Hex Inverter and to put a single pole single throw switch in series with it.
Then, I retested the power supply's output with and without the IC and most of the LEDs limiting power output.
Here is the pinout for the Hex Inverter:
Hex Inverter Pinout
I mounted the switch just to the left of the voltage adjust potentiometer.
I think one could simply remove the Hex Inverter chip to accomplish the same result. But if you did that, you would have to put the chip back in place to make those those special functions active again.
Sorry, but I do not have a complete schematic.

Here is a view of the addition of a switch to remove power to the Hex Inverter:
Hex Inverter Switch PCB View
In a nutshell, removing the Hex Inverter from the circuit doesn't improve regulation and current capability much at 5 volts,
but removing the Hex Inverter from the circuit helps a lot at 12 volts (but you still can't get much current out of it.
Spreadsheet showing test results: