Digital LC Meter
This unit was recently adopted as a radio club project and a number of members have now completed the PC build. The PC board is from a design by G4HUP and my version has some minor changes to allow for a backlight and a rechargeable PP3 battery and the associated components to connect to an external wall wart charger.
LCD displays with a backlight were procured and this was connected to the internal switched DC supply with a current limiting 8K2 resistor providing about 1mA.
A simple concentric connector has been fitted on the rear panel to allow the charging source to be connected.
The case, shown in outline form on the right, was made from 3mm birch ply and held together with wood glue and some internal structural supports -
The finished case was rubbed down and sprayed with several coats of clear acrylic car lacquer.
A drawing of the case may be downloaded from here.
The drawing on the right shows the circuit diagram of the modifications for a rechargeable battery and use of a backlight on the display.