Circuit Description - Ramsey Electronics Treasure finder TF-1 Instruction Manual

INTRODUCTION
Searching for buried treasure has been a childhood dream for most of us. If
we could only "see" what's under a few inches of soil who knows what
fascinating delights await us! Could it be antique coins, missing jewelry, or
that coffee can that Gramps buried his fortune in?
But one look at the metal detectors on the market today and our dreams are
dashed! Even the "inexpensive" versions of a metal detector unit may cost
upwards of one hundred dollars; with the "professional" units selling for five
to ten times more.
Enter the Ramsey TF-1 treasure finder metal detector unit. Using today's
superior integrated circuit technology and a little physics know-how, we've
come up with a great circuit that performs admirably with a minimum of
tuning. With great sensitivity, selectivity, and ease of tuning we offer the
easiest and most reliable way to start seeking buried treasure of your own!
TF-1 CIRCUIT DESCRIPTION
The following paragraphs describe some of the circuit theory for our metal
detector kit. Have a look at the block diagram (pg. 5) and schematic diagram
(pg. 12) and follow along.
We'll start by describing the entire circuit operation with a simple block
diagram. First of all let's get this search coil term figured out. What magic
properties happen when you wind a few turns of wire? Well, remember when
you hooked up that dry cell with the nail and the coil of wire? It did pick up a
few paper clips, now didn't it. This is due to the fact that a current through the
wire creates a magnetic field around the core. By the same token, if we were
to "cut" through this magnetic field with a wire, we would induce a voltage on
the wire. This is the principle that the power company generators use to
N
+
Figure 1 : Magnetism
"alternating"), that magnetic poles are also oscillating
from a coil of wire
back and forth.
produce electricity, as well.
When that same coil of
wire is used in an
alternating current circuit,
S
the nature of the search
coil begins to show itself.
As the electric current
races back and forth
through the wire (that's
why they call it
TF1 • 4