Christopher Zguris wrote:
>
> I just opened mine, couldn't wait to take a peak :-) . The case is two parts
> glued together, but not very well (_not_ welded).
>
> The unit has two flux-gate coils (I assume they're flux-gate), and a couple
> of smt ICs. Although it only generates 8 directions on the display, I
> suspect it _can_ do more, with the proper hacking & pin-debugging. The
> circuit doesn't look all that complicated to modify in any case, the thing
> is just _screaming_ "HACK ME! HACK ME!" esp at the $15-$16 price.
>
> etc etc.

The device you are referring to is similar to the Vector 2X compass
module. I have one in front of me. It costs $49.95 (UKP 31.73).
Available from (UK): Willow Technologies Ltd Surrey. Tel 01342 835 234.
(US): Jameco Company; they are at http://www.jameco.com

The Vector 2X has a 3-lead Microwire I/O, which is much easier to use
than I2C, but cannot so easily support multiple devices.

In Master Mode, the 2X gives out a continuous stream of data, which can
easily drive an LED/LCD display without any need of a processor, and
offers one-degree resolution.

In Slave Mode, a PIC-Chip or similar device could easily read the data;
the 40-page Application booklet gives complete interface info.

Power requirement is 5V (stabilised); current is 6mA (Master Mode) or
4mA (Slave Mode). The device loses its calibration if switched off, but
there is a 30 microamp power-down mode if the supply is reduced to 2.5
volts.

The 2X has 2 coils at right angles, and 4 chips on the opposite side of
the PCB. It may therefore be a more advanced version of your 2-chip
compass.


John Blackburn,
South London.