With lessons from the original build, it seems clear that some modifications could be made in order to increase the functionality of the hair trimmer. This page describes a follow-up rebuild of the same item but with some changes made and some problems fixed.

• It seems clear that the PCB of the Remington hair trimmer is just a switch and a charge circuit for the battery such that this PCB could be further reworked, in particular, pertaining to using a Lithium battery instead of a regular alkaline battery.
• Charging low-voltage devices from the mains seems a matter of the past and such devices could be charged using USB. One idea is to remove the existing power jack and replace it with an USB socket that will allow charging from a portable device or from any other outlet via a standard USB conversion. This should also resolve carrying a charger around.
• The switch of the Remington hair trimmer is essentially just a slide-switch that couples between two pads on the PCB in order to start the motor. It would be possible to replace this switch with a regular slide-switch even though the existing mechanism is not all that bad.
• Another issue with the conversion is that the old motor is rated at whereas on a full charge an 18650 Lithium battery discharges at , which seems to overdrive the motor and make the hair trimmer go a little too fast. It would be interesting to fit a potentiometer in order to slow down the hair trimmer, perhaps as a new or different parameter to the trimmer that would allow for speed adjustments.

In order to port over the slide switch a new PCB is cut up to size in order to match the switch pads. The modified PCB is not that much different from the original, it is essentially the same but with traces pulled for both switch pads at the bottom and without being able to tell when the switch is in the off position because it will not be used.

On the other side of the PCB, a Lithium battery trickle charger is connected to both the battery and with leads pulled to an USB port that will be mounted in stead of the old power jack. The circuitry is simple as well, with just copper traces being built between the components and with JST sockets mounted on the PCB for the quick removal of the battery and motor connectors.

A quick test is carried out in order to check whether the battery can be charged via the USB port by connecting an USB cable to the Remington. As it stands out, the red LED lights up, indicating that the battery is charging, followed shortly by a blue light indicating that the battery is charged. Upon turning on the device, the Remington seems to work perfectly, such that it seems that the battery holds the charge and is also fully charged.

For comparison, here are the two PCBs side-by-side. Both circuits are more or less the same, just with the remark that the older PCB is not as integrated as the new charger that has been fitted.

Given that all of that is in working order, the case is reassembled, with the remark that some of the inner struts had to be removed in order to be able to close the assembly completely.

Unfortunately, the red-LED indicator is now unaligned such that it could be removed or an LED pulled to the headers of the existing charger PCB LED lights.