You can view the previous posts here:
Part 1
Part 2
Part 3
Vector Charger (Switch)
The final design of the manual switch vector charger is complete. The slide switch fits in its spot on the left of the charger so users can turn the light on /off. Decided to switch to using a USB male port rather than the initial clip on male port for better compatibility with other USB 5V adapters.
There will be couple different backs to choose from to change the backlight effect.
Vector Charger (Linkable)
So my initial thought was to boost the signal going from one charger to the next so that the next charger has enough current to charge. I thought this would work in theory, but I encountered one problem, most DC to DC boosters prefer the input voltage to be higher than the output voltage. In my case the buck converter I was using would work with an input of 4.5v – 20v and can output 1.8V – 12V. I had it hard wired to output 5V regardless of the input, so ~5V from the regular adapter will output 5V for the next charger to consume.
This only worked in theory because one thing I did not see coming was voltage drop off when connecting the next charger. When the load from the original charger is engaged (i.e. led, and charging a vector); it caused the output voltage from the buck converter going to the next charge to drop from ~5V to ~4.3. This only came to light when I connected a Cozmo charger to the link usb port and it did not charge – this was because the voltage coming in was too low; Vector was more forgiving with the voltage drop.
The fix I finally came to was to use a different approach to the linking. Rather than using the buck converter to “boost” the current to the next charger, I will instead use it to power the LED and charging pins for the current charger its self and link the next charger to the main source. I had to change the voltage source to > 5V to work with voltage drops across the chargers; so I opted to use a 12V power supply.
With this new design I don’t have to worry about the voltage drop off at the next charger and the source voltage can be anything voltage withing the range of the buck converters inputs. So I would need to bundle the new charger with the linkable chargers or have the caveat that using a 5V supply will cause things to not work correctly.
The next thing now is to make a bunch of these and get them ready for sale.
