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Copper strip for inverter transformer

I want to build the 600W DC-DC Converter (SILICON CHIP, October & November 1996). The primary of the transformer is made from 0.315mm copper strip. There is also a strap made from 0.6mm copper strip.

Could you please advise me if there is a company that supplies sheet copper in small quantities, as used by hobbyists? (Z. F., via fax).

• The copper strip can be obtained from any model shop that has supplies for model aircraft, model cars, etc. They usually have a stand with various copper, brass and aluminium cross-sections.

Shadows on VU
display module

I have just completed a second digital VU meter (SILICON CHIP, May 2007) with the display module connected to the PC board via 40mm lengths of rainbow cable to facilitate fitting to a 2005 Studio preamp 1U rack-mounting case. All voltages are present and conductivity has been established between the 14 solder connections on the display unit and their points of origin on the PC board.

There are many dark shadows (almost 50% of the area), making the peak only indicators not to easy to see. Has anyone else experienced this? (D. G., via email).

• Our guess is that the shadows are caused by the added lead length between the LCD module and PC board and the stray coupling between the leads. Try separating the strands of the ribbon cable. Some terminating resistors of say 1kΩ between the ENable (pin 6) of the module and ground and the RS (pin 4) and ground may help. Or you may also need the resistors at the data lines (D7, D6, D5 & D4).

The shadows might be minimised by adjusting the contrast control, VR3. Alternatively, you could build it as described in the original instructions. If that fixes the fault, you know where the trouble lies.

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