Figure 3). As is seen from the photographs, the prototype
could be built into a very small case. It should not be
difficult, in fact, to redesign it to fit into an oversized pen.
Solder the battery holder to the PCB (two 8 mm
crimp terminals), attaching a round head (No. 2) paper
fastener to the negative (0 volt) crimp terminal.
Alternatively, the battery may be soldered directly to the
PCB by means of two solid-core wires; this must be done
quickly to avoid overheating. Solder the six solder pins
and the 14-pin dual-in-line (DIP) socket to the PCB. Take
note of the DIP socket’s orientation. Solder the resistors to
the PCB, the capacitors (take note of the orientation of
C4), the diodes, and Q1.
Insert the PCB in the case as shown. Mount on-off
switch S1 on the case and connect it as shown (this
should be switched off to begin with). VR1 is attached by
an end terminal to the solder pin and its wiper is taken to
the dispersive electrode, so that its resistance decreases
when the shaft is turned clockwise. Peizo sounder X1 is
attached to the solder pins.
Drill a hole in the case next to the switch, through
which the wire to the dispersive electrode (a metal grip or
metal plate) will be passed. Make sure that there is a
sound electrical connection with the metal grip or plate.
Then drill a hole for the active electrode, which is inserted
through the end of the case and soldered to the two
solder pins. This probe may be a needle with its sharp
point filed off with a fine file to make a sharp(ish) stub.
Drill holes on the lid of the case for VR1 and the peizo
sounder, gluing the sounder over the hole so that its
sound escapes through the hole. Insert U1 in the DIP
socket, observing anti-static precautions (first touch your
body to ground). The whole PCB, if desired, may be
secured in the case with a little epoxy glue. Be sure to
insert the battery the correct way in its holder, since the
circuit has no reversed polarity protection; a mistake here
could destroy the circuit. If there are any problems on
completion, the first suspects should be Q1 and U1.
NUTS & VOLTS
A year of experimentation preceded the development
of this circuit and the results gave me a new respect for
the potential risks of electricity, however small the
voltages and currents which are applied.
Skin resistance can vary between about 100K and
8M, depending on the day and the situation. Therefore, to
ensure consistency of results, skin resistance needs to be
kept relatively low. Use a little skin moisturizer where the
skin makes contact with the dispersive electrode, as well
as a little moisturizer on the wart itself.
Constructors are advised not to use the circuit where
current would flow across the head or the heart and never
in a case where a person uses a pacemaker or has any
history of epilepsy. All the precautions that apply to a
TENS device apply also to the Wart Remover.
When treating a wart on, for example, the lower or
upper arm, hold a metal grip (the dispersive
electrode) in the same hand. If it is not convenient to
use a grip, rest the limb to be treated on a metal plate
that is again connected as the dispersive electrode.
The active electrode, which is a sharp metal point
(but not too sharp), is rested directly and gently on the
top of the wart. If the wart is large (say 5 mm or more
in diameter), it might be a good idea to tackle one or
the other side of it first, since the Wart Remover is
unlikely to kill all of it at once.
Switch it on and apply the Wart Remover to a wart
for up to five minutes, then switch it off. If desired, use
VR1 as described to avoid any initial jolt and be
prepared to suddenly experience perhaps a minute of
sharp pain. If you do not see this through until the pain
subsides, the wart may not be destroyed.
The Wart Remover came as a welcome relief to
my son, who couldn’t bear the thought of further
treatment with liquid nitrogen. He claimed that the
Wart Remover was far preferable and that the pain was
“not bad” in comparison.
While this circuit comes with no guarantees, it is
nothing ventured, nothing gained! With several willing
“guinea pigs” and further volunteers queuing up, I
found that the Wart Remover was entirely successful,
most of the time. NV
470K ohm miniature linear potentiometer
100 µF electrolytic 16 V
IRF823 (or IRF510, BUZ11, etc.)
HEF4060BP (or equivalent — see text)
Peizo sounder (without internal electronics)
23 A or MN21 12 volt key chain (“remote”)
Two 8 mm crimp terminals for battery holder
Round head (No. 2) paper fastener for battery holder
6” long x 0.4” diameter brass pipe for dispersive electrode
One yard insulated wire to dispersive electrode
1.6” needle for active electrode
2-1/2” x 1-1/2” copper-clad board, small ABS plastic enclosure, four-pin dual-in-line (DIP) socket, epoxy glue, eight solder pins, solder, etc.