Project Description

The following product is intended to be a property – or hornc-protection device. It consists of a field of acoustical, ultrasonic, high sound pressure energy that is triggered when unauthorized intrusion is detected.

Detection consists of the following functions:

• A “trip wire” or closed system such as taped glass windows and doors where a break or open triggers the unit. This function is viaJ3.

• A “switch” input where a closure to ground such as a pressure switch, door, or entrance switch triggers the unit. This function is via J2.

• A "■+ level” input where a voltage pulse or level from other detection equipment such as an infrared intrusion, motion, or sound detec­tion system triggers the unit. This function is via JL

Test and Reset buttons enable total system con­trol.

Upon activation via the above, a moderately pow­ered sourcc of acoustical, ultrasonic energy is pro­duced. causing certain adverse effects to the intruder. These may be paranoia, severe headaches, disorienta­tion, nausea, cranial pain, an upset stomach, or just plain irritating discomfort. Most people are affected in one way or the other, with young women unfortu­nately being the most sensitive. External adjustments enable the user to select clearly audible sounds that serve as an alarm, high-frequency energy that pro­duces the physiological effects, or a combination of both.

The sound pressure level is less than 130 db and will not produce permanent damage if exposure is kept to a minimum. Obvious prolonged exposure is not encouraged for these reasons. A rule of thumb is to keep exposure to less than I hour with a frequency less than 20 kHz at a sound pressure of 105 db or over.

The system consists of the central power and con­trol unit that powers up to six remotely located trans­ducers. These are now positioned to take advantage of potential entrance and intrusion areas, considering that each transducer can produce up to 118 db meas­ured at 1 meter. Since the sound pressure level is log­arithmic. an attenuation factor of -3 db must be factored in every time the distance is doubled from one of the transducer stations.

□river Circuit Description

A timer (IC2) is connected as a stable, free-running multivibrator whose frequency is externally con­trolled by pot R9. The trimmer resistor (RIO) selects the range limit of R9. Capacitor C5, along with the resistors, determines the frequency range of the device (see Figure 28-2).

The square wave output of 1C2 is via pin 3 and is connected to metal-oxide-semiconductor fieid effect transistor (MOSFET) Q2.The drain of Q2 is DC biased through Ll. The amplified square waves are fed to the transducer via resonating coil LI and capacitor C8, along with Q spoiling resistors. R13 through R16. Resonating coils (L2A and L2B) are selected to tune out the inherent capacity of the transducer at their upper-frequency limit, usually around 25 kHz. A sinusoidal wave is generated and allows the transducers to operate at a higher peak power level than the equivalent voltage square wave would. Resonant peaking of the voltage is also obtained. These transducers, unlike their electromag­netic counterparts, have a tendency to draw high cur­rent at higher frequencies. This effect is compensated to an extent by power resistors R17A and R17B. Note the wave shapes shown are at a fixed frequency of 20 kHz.

Timer IC1 is similarly connected as a stable, run­ning multivibrator and is used to produce the sweep­ing voltage necessary for modulating the frequency of lC2.The switch section of R2/S2 activates it, and this sweep repetition rate is controlled by the pot sec­tion R2. Resistor R3 limits the lower range of this repetition time. Capacitor C2 sets the sweep time range. Output from IC1 is via pins 6 and 2 where the signal ramp function voltage is resistively coupled to inverter transistor Ql via resistor R4.The output of Ql is fed to pin 5 of 1C2 and provides the modula­tion voltage necessary to generate the sweeping fre­quency action required. Note that this signal is easily
disabled via the switch section of R2/S2.This is a con­venience when initially setting or checking the range of 1C2 as it eliminates the constant varying fre­quency.

Project Description

Figure 28-2 Phaser pain field property guard schematic

Power is supplied to the system via a conventional step-down converter wall transformer,!!, which con­nects to the system via the DC JACK chassis mount connector. Power is controlled by switch SI that is part of the frequency control pot R9. A light-emitting diode (LED) indicator lamp and an associated cur – rent-limit resistor (R11) tell when the system is ener­gized.

Pain Field Property-Protection Guard

Pain Field Property-Protection Guard

Figure 28-1 Phaser property protection guard

This chapter otfers an excellent home – and property – protection project when properly built that provides a low-liability deterrent to unauthorized intrusion from both two – and four-legged threats. Once activated, strategically placed transducers project an uncomfort­able and disorientating field of complex acoustical sound and shockwaves. It is a harmless effect yet dis­courages most intrusions in a defined area.

A reasonably simple electronic system can power up to eight individual transducer emitters positioned in the target area (see Figure 28-1). Activation can be an open or closed fault switch or a voltage level such as that produced by our laser property guard described in Chapter 12.‘‘Laser Property-Protection Fence.” Together these projects can be interfaced to produce an effective intrusion detection and deter­rent system. Expect to spend $50 to $100 with hard – to-find parts available at www. amazingl. com. The complete parts list is outlined in Table 28-1.

Warning: Do not operate this system at continuous, high output at frequencies below 20 kHz. Daily sound pressure exposures in excess of 1 hour at 105 decibels (db) may lead to hearing impairment. When properly used, this device provides a limited liability deterrent. It should not cause permanent damage or trauma.

Subassembly Pretest

To conduct a test on the device, follow these steps:

1 Turn pots counterclockwise and install eight fresh A A batteries into the BH1 holder, as shown in Figure 27-5.

Note that a variable bench supply capable of 12 volts-direct current (vdc) at 1 amp with a volt and current meter can be a great conven­ience for the remaining steps and for the test­ing of other similar circuits.

Subassembly Pretest

Cut out center of two 3.5" plastic caps by placing them on the enclosure tube and cutting out the center section with an x-acto knife using the inner wall as a guide.

Drill hole in handle for pushbutton switch S1 It may be necessary to recess the hole so nut will reach shank

Note that hole in EN1 for handle is best cut with a 1 g" circle saw Fit must be tight to properly secure handle in place The handle serves as the housing for the single 9 volt or 8 AA cells


Panel is cut from аз|х 3^" piece of 035 aluminum Cut согпеге to approach a circular shape.

Subassembly Pretest

Front Panel Fab

Figure 27-5 Final blowup

2. Push button SI and note a loud, piercing wave coming from TD1. Measure a current of 300 to 400 milliamperes in a series with a batter}’.

3. Rotate R9 and note that the frequency increases to above the audible range. Then measure a current of 100 to 200 milliamperes.

4. Note the wave shapes shown in Figure 27-2 for those who have a scope.

5 Turn on sweep control R2/S2 and note the fre­quency being modulated by a changing rate as this control is adjusted. Use caution as certain sweep rates may cause epileptic fits and other undesirable effects. Sweep rates between 7 and 20 per second should be used with cau­tion.

Final Rssembly

The final steps arc as follows:

1. Cut the rear panel from а З’Аі – x 3V4-inch piece of aluminum. Add holes for the controls as shown in Figure 27-5.

2. Create the CAP2 and CAP3 retaining caps from a 3]/2-inch plastic cap. This is easily done by placing a cap over the end of the main enclosure and carefully removing the center section with a sharp knife, using the wall thickncss as a guide. These reworked caps now retain the transducer and the rear panel to the main enclosure.

3. Create EN1 and HA1 from the material indi­cated on the parts list. Add a hole in the main enclosure for the insertion of the HA1 handle section. The hole must provide a tight fit. Glue the parts together.

4. Create the final assembly as shown.

Note that the frequency range with the values shown is 4 to 20 kFlz. The frequency range can be changed by increasing the value of C5 to lower it or by decreasing the range to raise it. Experiment for a desired result. The sweep range with the value shown is 4 to 50 Hz. C2 can be changed in a similar function.

Sound pressure measurements will vary from 130 to 100 db at 18 inches depending on the frequency. Certain sweep rates between 5 to 20 per second may cause dizziness or epileptic fits.

Subassembly Pretest

Table 27-1 Phaser pain field gun project parts

Ret # Qty Description DB#

R1,6,8,12 4 IK. ‘/i-watt resistor (br-blk-red)

R2/S2 500K to 1 meg pot/swiich, 17 millimeters

R3 2.2K. ‘/«-wait resislor (red-red-red)

R4.5 2 I OK.’ M-watt resistor (br-Ы k-or)

R7 10-ohm,1A-watt resistor (br-blk-blk)

R9 ЮК pot. 17 millimeters

RIO 5K trimpot, horizonia I

R13 1 30-ohm, З-wall resistors (or-Wk – blk)

С1,4 2 .01 mfd/50-volt disk capacitor (103)

C3 t0() mfd/25-voll vertical electrolytic capacitor

C2 10 mfd/Z^-voll vertical electrolytic capacitor

C5 .01 mfd/50-vull polyester capacitor

Г6 1000 mfd/25-volt vertical electrolytic capacitor

C8 .01 mfd/2 Kv disk capacitor


L2.3 2 1 millihenry inductors in place of RlS and Rl6,as marked on PCB 1UIMH

LI Inductor—2 Hitachi 30.48 E cores and mating bobbin, as shown in Figure 27-4 (UPPPl LI

Q1 PN2907 PNP GP transistor

Q2 IRF530 or 540 N channel metal-oxide-semiconductor field effect transistors


Table 27-1 Cnntinued

Ref. # Qty. Description QB#

IC1,2 2 555 DIP timer

HS [ Heatsink bracket shown in Figure 27-4

SW1/NUT 6-32 X ’A-inch screw and nut

CLl 1 9-volt battery clip

BH1 Eight A A cell holders for 1.5 volt batteries (В 1)

SI SPST pushbutton switch

PCPPP1 PCB or use perforated vector board


TD1 Polarized 130 db piezo transducer


WR1 3 feet #24 vinyl hookup wire, red and black piece

WR2 5 feet #24 magnet wire to wind Ll

САРІ 17/«-inch plastic cap (A11Ы)

CAP2,3 2 3 V2-inch plastic cap (A3 xh ), as shown in Figure 27-5

RPl 3 ‘/s-inch square #22-24 aluminum, as shown in Figure 27-5

EN1 3 ‘/2- OD X 7-inch PVC tube, as shown in Figure 27-5

HANDl 1 7/s – OD X 6-inch PVC tube, as shown in Figure 27-5

Circuit Theory

A timer (1C2) is connected as a stable, free-running multivibrator whose frequency is externally con­trolled by pot R9 (see Figure 27-2). Resistor RIO selects the range limit of R9. Сapacitor C5, along with the resistors, determines the frequency range of the device. The square wave output of 1C2 is via pin 3 and is resistively coupled to power amplifier Q2.The drain of Q2 is DC biased through resonator choke LI.

The square wave output signal is now fed into transducer TD1 in a series with resonating coils L2 and L3 in a parallel com bination. The resonant action among the inherent capacities of TD1, the tuning capacitor C7, and the inductance now produces a sinusoidal-shaped wave peaking around 25 kHz or the upper limit of the tuning range. This signal wave­form now has a peak-to-peak voltage several times that of the original square wave. Transducer TD1 nov can take advantage of these peak voltages to produce the high-pressure-level sounds necessary without exceeding the high average ratings of an equivalent voltage-level square wave

Timer Id is similarly connected as a stable run­ning multivibrator and is used to produce the sweep­ing voltage necessary for modulating the frequency of

Figure 27-2 Phaser pain field gun schematic

Circuit Theory

Figure 27-3 PCB wiring

lC2.This sweep repetition rate is controlled by pot R2, and resistor R3 limits the range of this repetition time. Resistor R1 selects the duty cycle of the pulse, whereas capacitor C2 sets the sweep time range. The output for II is via pins 6 and 2 where the signal ramp function voltage is resistively coupled to inverter tran­sistor Ql via resistor R4. The output of Ql is fed to pin 5 of 12 and provides the output modulation volt­age necessary to vary the frequency as required. Note that the modulation signal is easily disabled via R2/S2.

Power to the system comes from battery B1 and pushbutton SI. Capacitor C6 guarantees an AC return path for the output signal. Power to the driver circuits IC1 and 1C2 come through a decoupling net­work consisting of resistor R7 and capacitor C3.

Construction Steps

To begin the assembly of the gun, follow these steps:

1. Lay out and identify all the parts and pieces, checking them with the parts list.

2. Cut the HS1 heatsink bracket from a.75 X 2 X.065 aluminum piece. Bend it 90 degrees at its midsection and drill a hole for the SW1/NU1 screw and nut. Then attach it to Q2 as shown later in Figure 27-4.

3. Figure 27-3 shows the assembly using a printed circuit board (PCB) available through www. amazingl .com. Experienced builders may use a piece of Л-inch grid perforated vec­tor board. Use the drawing for parts location and the schematic for the connections. Certain leads of the actual components will be used for connecting points and circuit runs. Do not cut or trim them at this time. It is best to tem­porarily fold the leads over to secure the indi­vidual parts from falling out of the board holes. If you obtain a PCB, you may omit this step.

4. Insert and then solder in the designated com­ponents:

a. Insert the ’/4-watt resistors: R1, R3, R4, R6, R7, R8, and R12.

b. Insert RIO and R13.

c. Solder in the control pots R2/S2 and R9. Use short pieces of bare-wire leads from the component pins to the respective holes in the PCB. Note these controls must be as close to the board surface as possible.

Note that Rll and R14 are not used and the positions for R15 and R16 are used for components designated as L2 and L3.

d. Insert capacitors Cl, C4, C5, and C8.

e. Insert electrolytic capacitors C2, C3, and C6, noting the polarity. Note that C7 is not used in this circuit.

f. Insert semiconductors Ql, Q2, IC1, and IC2. Note that Q2 is attached to heatsink HS1 via SW1/NU1.

g. Insert two wire jumps.

h. Insert the two 1 millihenry inductors in place of R15 and R16.

i. Insert the red lead of CLl and the 10-inch lead for SI as shown.

j. Insert two 10-inch leads for transducer TD1.

Circuit Theory

Figure 27-4 Assembly of inductor LI and heatsink HSI

5. Assemble the LI choke coil by wrapping 50 turns of #24 magnet wire on the nylon bobbin as evenly as possible. Leave two inches of leads for connection to the circuitry. Assemble the E core, as shown in Figure 27-4. Shim each side with pieces of yellow cardboard strips of

.003 inches each for a total of.006 inches. If you have an inductance capacitance bridge, measure 1.5 millihenry s.

6. Wire in the inductor and secure it to the board with room temperature vulcanizing (RTV) silicon rubber or another suitable adhesive.

7. Preconnect all the leads toTDl, Si, and CLl.

8. Check the complete wiring for potential shorts, wire bridge shorts, poor solder joints, the correctness of the components, and the position and orientation of Ql, Q2, C3, C6, ICl, and IC2.

Supplementary Rpplication Note

This device can provide hours of entertainment for adults and children alike. For example, a small box containing an oscillator at a frequency of 25 kHz

J1 headphone jack

R19/S1 on/off and volume control

R12 frequency tuning


Supplementary Rpplication Note

Supplementary Rpplication Note

Unit without parabolic reflector where transducer is mounted as shown in Fig. 26-4

Figure 26-7 Final assembly without a reflector

could be well hidden somewhere. The highly direc­tional characteristics of the device with its ability to respond to various signal levels enable a quick bear­ing to be made 011 the hidden source and the fun begins. It should be noted that ihe detection range could be in excess of a quarter-mile! This allows great flexibility in hiding the oscillator, using only your imagination for making detection difficult. Along with my children and friends. T have had many enjoy­able hours and good laughs playing with this equip­ment.


You may easily record the output lo a recording device by connccling the auxiliary input to the head­phone output jack. A CiY’’ adapter can be used for simultaneously plugging in the headset to monitor the recorded sounds. Two sets of headphones can be used with the adapter, and the output impedance is 8 ohms.

Table 26-1 Ultrasonic microphone parts

Ret # Qty. Description DB#

Rl, 21 2 10 ohm, ‘/< watt (br-blk-blk)

R2 3.9K, ‘/4 watt (or-wh-red)

R3 10 megs, 4* watt (br-blk-blue)

R4,8,18 З 10K, ‘/4 watt (br-blk-or)

R12 ЮК, 17-millimeter pot

R5,7,10,11,14,15 6 lOOK,»/4watttbr-bIk-yel)

R6, У 2 470K. ‘/4 watt (yel-pur-yel)

R13 2.2K,’/« watt (red-red-red)

R16 1 meg, ‘/■> watt (br-blk-grn)

R17 4.7K, ‘/4 watt (yel-pur-red)

R19/S1 10K, 17-millimeter linear pot and switch

R20 47 ohm, ’/4 watt (yel-pur-blk)

Rd Select for dampening transducer circuit—10 to 47K, ’/4 watt

Cl 10 mfd, 25-volt vertical electrolytic capacitor

C2. t2 6 .01 mfd, 25-volt disk or plastic capacitor

D1 1N914 smatl-signat diode

C8 .047 mfd, 50-volt ptastic capacitor

C5,7,13,14 4 .1 mfd, 25-volt disk or plastic capacitor

C9,16 2 100 mfd, 25-volt verticat electrotytic capacitor

C15 1,000 mfd, 25-vott vertical etectrolytic capacitor

LI 27 millihenry mduclor #IU27H

Qt J202 n-channel FET

11 LM074 4-second OP amp DIP

12 LM386 audio amplifier DIP

J t 3.5-millimeter stereo audio jack wired for mono

TD1 25 kHz acoustical receiving transducer #1UTR8925

SHt 18 inchcs Shielded mike cable

PB1 PC or.1 gnd perforated vector board, 2.25- X 2.25-inch

BAF1 Thin piece of 2.25- X 2.25-inch plastic for insulating

BtJl 1 X ‘/г x 3/if, watl neoprene bu&hing

CL I Battery clip with 12-inch leads

PARA12 Optional parabolic reflector #IUPARA12


Supplementary Rpplication Note

This project shows how to build a directional, hand­held device capable of driving off both wild and domestic animal pests (sec Figure 27-1). This device produces high-pressure-level sound at complex fre­quencies mostly above that of human hearing. This sound is painful to many animals as their hearing is much more acute than humans. The unit is tunable and can also be adjusted to be very annoying to peo­ple when exposed at close range.

The circuitry is housed inside an easily obtainable piece of polyvinyl chloride (PVC) tubing and resem­bles a large ray gun. The output controls are on the rear panel with the batteries in the handle. Expect to spend around $25 to assemble this sound gun. All the parts are readily available, with the hard-to-find items available at www. amazingl. com.

Caution: Exposure below 20 kHz at a sound-pres – sure level of 105 decibels (db) in excess of 1 hour may cause a hearing impairment.

This project shows how to construct a moderately powered, directional source oi continuous, adjustable, high-frequency, time-variant acoustical shockwaves. The output energy of the devicc is conservatively rated at 125 db. The frequency is programmable or is con­stantly sweeping at an internal preset rate and is vari­able approximately from an audible 5 to 20 kHz. The unit is intended for use as a research tool in the study of animal behavior, acoustical experimentation, or as a source of intense, directional, acoustical, high-fre­quency sound for other scientific and laboratory appli­cations. The device is excellent for use in agricultural applications such as flushing out rats and other rodents from granaries, silage bins, chicken coups, and so on.

It is to be used with discretion and not treated as a toy. Caution must be used as exposure to most people causes pain, headaches, nausea, and extreme irritabil­ity (younger women are especially affected). Do not, under any circumstances, point the unit at a person’s ears or head at close range, as severe discomfort and possible ear damage may result. Usage on dogs and other animals must be done with discretion to avoid excessi ve d iscom fori.