Re: [mowbot] Thank Dave

Dave Everett (deverett nospam at
Sat, 01 Feb 1997 09:27:47 +1100

KEN_REED nospam at wrote:
> Noticed the MowBot webpage has been updated with info about your sonic
> surface detector and a compass. Thanks for keeping the effort going.

My pleasure. As you can see the surface detector circuit has been
simplified. I removed the microcontroller and use the free opamps to
perform a thresholding function on the signal. Parts cost was about $6.
All Electronics Corp sell the
type of ultrasonic sensor I used for $2.50 a pair.

Unfortunately I am still waiting on the DCM-64 gearmotors I ordered from
All Electronics corp. I sent them a money order on the 25/11/96,
shipping was estimated at 6-8 weeks so I should receive them in the
next week. Then I can build a chassis to test the sonar sensors on.

I also ordered a 2XT gimballed digital compass yesterday from Jameco.
Precision Navigation won't accept International money orders, but
thankfully their compasses are sold by many other companies. The
gimballed compass is about twice the price of the standard compass, but
the gimballing helps minimise heading errors caused by the vehicle being
on other than level ground.