VGA Convertor

Due to the VGA converter drawing lots of power I have decided to make it available when the machine is powered via mains. It adds too much drain to the battery and is not really useful unless you are at a desk anyway.

Originally I was going to have everything powered by the battery and the unit could be powered off via a switch but would always be charging if plugged in.

The machine will now do the following...

1) Always charge when plugged in.
2) The VGA convertor will be powered when plugged in only (from the incoming 5v).
3) The machine can be powered externally while the batteries are charged or you can use the battery to power the machine and the small screen. Thus the small screen is only available when on battery power and turned on. Where the machine is available if using battery or on external power (as the original machine was) dependant on the switch position.

Battery Testing

Tested the battery (2000mah) and found that with the small screen and the machine powered it will provided about 45mins to an hour. Have managed to get the battery I was originally going to order (but was out of stock) which is 6000mah so gives several hours of usage.

Screen

Mounted the screen in the case.

Firstly marked out where the screen should go and used the dremel to cut out the hole. I left a small set of lugs from the lower plastic area so that the screen can sit on them. It turns out the screen was exactly the same height as the indent in the air slots so it fits nicely.

Inserted screen and adjusted to fit correctly.

Hot glued the screen and the board into place.

Tested to check everything works ok.

Battery & Charging Circuit

Well some parts I'd ordered arrived so I decided to solder them together to test out the chargeable battery.

Here is the current charging circuit connected to the mains and the Gonbez. I can remove the power from the main socket and the battery takes over.

This should hopefully provide a 5v input which will charge the LiPo battery when the unit is plugged in. I intend to wire a switch in between the charging board and the step-up board so that I can turn off the machine without stopping it charging.

The charge circuit takes 5v in but the battery is 3.7v. To be able to supply the 5v needed for all the internal boards I am using a step-up board that will take the 3.7v to 5v. I have tried it with the Gonbez board and it runs this ok.

Mini TV Screen

I have a very small TV screen which I bought. The next step is to wire up the screen check it works with the output from the BBC.