Figure 2. Here, you see that current is limited across the probes.
Figure 3. The project is compact and can be built
into a large pen casing.
not the same.” In fact, in many cases, the wart melted
with a fizzle even before treatment was over. The skin
immediately surrounding the wart may be irritated for
a few hours and there may be a slight swelling around
Ultimately, a scab is likely to form and, perhaps three
weeks after treatment, the wart should “expire” and come
off — or, in some cases, partly come off. Don’t remove a
wart too soon or break its surface, since this could leave
a deep wound and infection could represent a risk. If it is
left alone, there should be no infection.
If a treatment should have little or no effect, it would
be sensible to consult a doctor.
The Wart Remover uses a single 4060 CMOS oscillator IC (see block diagram Figure 1), which incorporates a
14-stage binary divider. I chose this IC for its simplicity (it
incorporates the oscillator), for the square wave outputs
provided by its internal divider, and its ability to have three
separate outputs employed for three separate purposes.
The fourth-stage output (pin 7) switches a solid-state
switch (a power MOSFET) to pulse 24 volts through
the electrodes at the required frequency. The fifth-stage
output (pin 5) powers a voltage booster ( 12 to 24 volts —
see the top of Figure 1) and the sixth-stage output
activates a peizo sounder that gives a direct indication
that the oscillator-divider IC is working.
NUTS & VOLTS
One of the electrodes is positive (+ 24 volts, called the
dispersive electrode and labeled DE) and may either be a
metal grip held in the hand or a metal plate applied to an
area of skin near a wart. The other electrode is negative
(0 volts, called the active electrode and labeled AE) and
this is a sharp(ish) metal point used for direct contact
with the wart.
I settled on a 24 volt, 21. 27 kHz square wave (or
thereabouts), applied to a wart for five minutes. I found
that pulses of 1 mW power (minimum) passing through
the wart internally were required to achieve any effect and
that 3-6 mW pulses were adequate.
Current across the probes (see Figure 2) is limited by
R4 to 2.4 mA (maximum) so as to protect the circuit if
the probes should be short circuited. One needs to also
factor in the conductivity of the flesh and this rarely falls
below about 200K; therefore, little more than about 100
µA would course through the wart itself.
The frequency of the oscillator section is roughly calculated by the formula f=1/(2.2 x R1 x C1), although this
becomes undependable, in practice, at higher frequencies.
I selected the Philips HEF4060BP IC for U1. Note that
different makes of this IC can affect the frequency and, if
a different make is used here, I would suggest that the
frequency be adjusted with the help of a frequency meter
(adjust the value of R1). Having said this, frequency is
unlikely to be critical.
Q1 provides an efficient switch for pulsing the voltage
through the flesh and may be almost any power
MOSFET. I used an IRF823 that I obtained in an All
Electronics bargain pack — presumably a high voltage
device in the IRF series. The more common IRF510
would serve just as well. C4 serves as a supply decoupling capacitor and S1 as an on-off switch.
Some “trappings” are added for convenience and
comfort. Most importantly, a 470K potentiometer is
inserted in the dispersive (+ 24 volts) electrode’s lead to
prevent the possibility of a brief electrical jolt at switch-on
or on first applying the active electrode to a wart. In this
case, the Wart Remover is switched on and the active
electrode is applied, then VR1 is turned up (that is, its
resistance is reduced). Further, an audible sign of life
is added to the circuit by wiring a peizo sounder to the
sixth-stage output. This uses a 100K series resistor so as
to provide a gentle beep.
For those who are likely to use the device more often,
a standard “battery low” circuit could also be added.
Lastly, the fifth-stage output is used to raise the battery’s 12
volts to 24 volts by means of a standard voltage doubler.
The circuit is thus directly powered by 12 volts, while a
boosted 24 volts is switched through Q1 to the electrodes.
Most importantly, this boosted voltage helps the circuit
overcome skin resistance, so that it is able to provide the