This was a simple little project to convert a set of solar powered lights to indoor use. The meagre brightness was boosted considerably, with the LED drive current going from 13mA to 36mA. The paralleled LEDs seemed to have even brightness to share the load and they lasted at least this season.
A USB C socket allowed on an old USB charger to be upcycled for the 5V supply. The circuit supplies approximately 2.7V AC to the lights, which I found was a requirement for 2 sets of solar lights and some battery sets too. Other brighter sets were operating from 26V DC to 40V AC.
A PICAXE 08M2 toggled 2 opposing outputs, which were fed to a L9110 (PDIP-8) H-Bridge to drive the LEDs via a series resistor. While still working with old stripboard this H-Bridge proved quite useful.
The 08M2 was clocked at 8MHz to achieve 115Hz AC output. Program execution time provided 140us deadbands when toggling the outputs, which prevented shoot-through current on the H-Bridge.
There was a pot to control brightness/current, but the maximum was fine, so I’d recommend ditching that part of the circuit and connecting the H-Bridge directly to the 5V rail as I did in a later project. It boosts the output to about 45mA unless the 33 ohm resistor is replaced with a higher value.
Attached are the key files and more detailed is held here .
A USB C socket allowed on an old USB charger to be upcycled for the 5V supply. The circuit supplies approximately 2.7V AC to the lights, which I found was a requirement for 2 sets of solar lights and some battery sets too. Other brighter sets were operating from 26V DC to 40V AC.
A PICAXE 08M2 toggled 2 opposing outputs, which were fed to a L9110 (PDIP-8) H-Bridge to drive the LEDs via a series resistor. While still working with old stripboard this H-Bridge proved quite useful.
The 08M2 was clocked at 8MHz to achieve 115Hz AC output. Program execution time provided 140us deadbands when toggling the outputs, which prevented shoot-through current on the H-Bridge.
There was a pot to control brightness/current, but the maximum was fine, so I’d recommend ditching that part of the circuit and connecting the H-Bridge directly to the 5V rail as I did in a later project. It boosts the output to about 45mA unless the 33 ohm resistor is replaced with a higher value.
Attached are the key files and more detailed is held here .