OK, I know it goes against all best practise, but I still wanted to experiment(play). I’d previously noticed a fair amount of voltage sag on PICAXE outputs under load. So why not check if the forward voltage of LED fairy lights would help the outputs stay within the maximum 25mA sink/source?
I was converting 1 Solar and 4 battery LED strings to mains and each string required about 2.7V AC. The eventual projects were always going to use H-Bridges, which provided a little more oomph, but it was fun to see a 08M2 successfully drive a string without a series resistor.
I can’t bring myself to recommend this approach, but for anyone who may be interested my thoughts and findings for internal resistance of outputs, voltage drops and LED failure modes are shown in the schematic.
The PICAXE managed to raise the current for a set of fairly dim ex-solar power lights from 13mA to 20mA. At 8MHz the 08M2 toggled 2 outputs at 114Hz and in the eventual project the program execution time provided 140us deadbands to prevent shoot-through current on the L9110 PDIP-8 H-Bridge.
Attached are all the files and the master copy is held here .
I was converting 1 Solar and 4 battery LED strings to mains and each string required about 2.7V AC. The eventual projects were always going to use H-Bridges, which provided a little more oomph, but it was fun to see a 08M2 successfully drive a string without a series resistor.
I can’t bring myself to recommend this approach, but for anyone who may be interested my thoughts and findings for internal resistance of outputs, voltage drops and LED failure modes are shown in the schematic.
The PICAXE managed to raise the current for a set of fairly dim ex-solar power lights from 13mA to 20mA. At 8MHz the 08M2 toggled 2 outputs at 114Hz and in the eventual project the program execution time provided 140us deadbands to prevent shoot-through current on the L9110 PDIP-8 H-Bridge.
Attached are all the files and the master copy is held here .
