My daughter got a toy train which uses AA sized battery cells to operate. It has space to put two AA cells in parallel, so it requires just 1.5 V to work. To avoid buying AA cells, I tried to make it rechargeable with a 18650 lithium-ion cell with protection board having USB port. But… Continue reading 3.7 to 1.5 V Buck Converter with MC34063AP
Here is the schematic and details for creating one channel relay module. It would be capable of driving both DC and AC current when appropriate relay is used. We can connect output pin of most of microcontrollers including Arduino to control it.