Category Archives: Electronic Gadgets for the Evil Genius BOB IANNINI

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.

Special Note: Utilizing a Standing UJave

It is possible to produce a standing wave at the face of the transducer TD1 and improve the system sensi­tivity. Point the device at a steady, low-intensity source of high-frequency energy and carefully adjust

Special Note: Utilizing a Standing UJave

Note shielded cable is 18" and is routed through a small hole in the raar cap CAP3 and in PARA12 reflector

TD1 is fitted into bushing BU1 Assembly is then inserted into the 5.5” x 1.625” diameter enclosure TUBE and is spaced by Ihe O-RING. This scheme shock mounts the Ira nsducer and secures it in place

Transducer is wired as shown in set Fig 26-5

Figure 26-6 Final view showing a reflector

the distance of the 1 X 1" metal flat plate relative to the transducer face, noting an increase in the signal. This effect will occur at half-wave multiples with the most pronounced being closest to the face. Use your own ingenuity in retrofitting this simple step.

Circuit Description

An ultrasonic transducer mike (TD1) picks up high – frequency sounds and converts them to electrical sig­nals via the piezoelectric effect (see Figure 26-2). Inductor LI tunes the inherent capacity of the trans­ducer to a window frequency centering around 25 kHz. This parallel, equivalent resonant circuit pro­duces a high-impedance signal source that is coupled to field-effect transistor (FET) Q1 amplifier through capacitor C2. Resistor R1 and capacitor Cl decouple the bias voltage to the drain. Layout and input lead shielding is important, as this section is prone to noise, feedback, and extraneous signal sensitivity.

The output of Ql is taken across the drain resistor R2 and is capacitance coupled to amplifier II A. Gain is set to X50 by the ratio of resistors (R6/R4).

The output of 11A is AC coupled to the combina­tion mixer/amplifier 11B through capacitor C4.The output of oscillator 11C is coupled into the circuit by a “gimmick” capacitor, CM. This is a short lead from pin 8 of IC1 and is twisted with a similar lead from pin 2 of 11B. (It is suggested to check performance without this gimmick.) The oscillator now generates a frequency that is mixed with the picked-up signals. The resultant is two signals, one being the sum and the other the difference.

Capacitor C7 and resistor RI7 form a filter net­work attenuating the higher-frequency component of the mixed frequencies while allowing the lower fre­quency to pass by a factor of 20 decibels (db).The lower-frequency results are the difference between the oscillator frequency and the actual signal fre­quency. This is similar to a superheterodyne effect. The high frequency is obviously bypassed by filter C7 and R17. The filtered signal, being the composite dif-

Circuit Description

"Gimmick"- See text as may

Proper routing of input power leads will improve noise figure.

Leads to J1 must be short and direcl as possible

Leads lo power must be routed direct to underside of mounting plate.

Rd is chosen to dampen transducer response Suggested value is around 3SK.

Twist all lead pairs wherever possible

Figure 26-2 Ultrasonic microphone schematic


Circuit Description

ference, is rectified by diode Dl and integrated with capacitor CB. This signal is in the audio frequency range and is what you actually hear. It is tuned by control pot R12 in the oscillator section and enables the selective tuning of certain target frequencies within an acceptance window of the transducer TD1. These resulting audio frequencies are coupled to vol­ume control R19 through DC blocking capacitor CIO. Capacitor Cl2 bypasses any higher frequencies that may leak through. The arm of R14 teeds the audio signal into headphone amplifier 12. The output is H ohms and is capacitance-coupled to the headset jack J1. You may use a small speaker in a quiet loca­tion for group listening. Network R21 /С4 further attenuates any further higher frequencies.

Power to 12 is decoupled through resistor R20 and capacitor С15. This provides circuit stability, prevent­ing feedback oscillations and other undesirable effects.

The operating points of 11 A, 11B. and 11С are set at the supply voltage midpoint selected by divider resistors R7 and R11. Resistors R5, RIO, and R15 compensate for offset currents.

Construction Steps

To begin constructing the device, follow these steps:

1. Identify all the parts and pieces and verify them with the bill of materials.

2. Insert the components, starling from one end of the perforated circuit board, and follow the locations shown in Figure 26-3, using the indi­vidual holes as guides. The board is cut 2.25 x 2.25 X.1. A printed circuit board (PCB) is also available from www. amazingl. com.

Use the leads of the actual components as the connection runs, which are indicated by the dashed lines. It is a good idea to trial-fit the larger parts before actually starting to solder.

Always avoid bare wire bridges, messy solder joints, and potential solder shorts. Also check for cold or loose solder joints.

Pay attention to the polarity of the capacitors wilh polarity signs and to all the semiconduc­tors. The positioning of the control pots must

Circuit Description

allow physical alignment with the mounting holes in RPl.

3. Cut, strip, and tin the wire leads tor connect­ing to J1 and solder them. These leads should be 2 inches long and twisted.

4. Fabricate the CHASl chassis, the RPl front panel section, the EN1 enclosure, and the HAND1 handle, as shown in Figure 26-4.

5. Prepare the SHI shielded cable at both ends as follows. If the optional reflector is used, you will need a length of 18 inches; if not, you will need 6 inches. This is shown in Figure 26-5.

a. Carefully remove 3A of an inch of the outer insulation, being careful not to nick the shielded braid.

b. Shred the shielding braid using a pointed object, such as a pin, and twist it into a lead. Carefully tin only the ends to hold the wires together.

c. Carefully strip 4a of an inch of the insul­ation from the center conducior and tin.

d. Check the finished cable for shorts or leakage with a high-resistance meter.

6. Solder the inductor LI and the damping resis­tor Rd, as shown in Figure 26-5. Solder one end of the SHI cable, being careful not to overheat the transducer pins or the insulation of the center conductor. Overheating these pins will ruin this part. If in doubt, you must perform a simple test of measuring a short cir­cuit to the metal case of the part to the shorter pin. If this resistance is above 1 ohm, you have trashed this part and need a replace­ment. The inset in Figure 26-5 suggests using mechanical connections such as crimpling, wire nuts, and so on.

7. Assemble as shown. Figure 26-6 shows an assembly using the parabolic reflector, whereas Figure 26-7 shows one without.

Note that hole in ENt 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 orS AA cells

From Figure 26-3

Cut out center of 3.5” plastic cap by placing on the enclosure tube and cutting out the center section with an x-acto knife, using the inner wall as a guide

Front Panel Fab

Dashed lines indicate t/2" mounting lip. Note clearance holes for SW1 mating to holes in RPt rear panel




Circuit Description

Panel is cut from a3|x 3|’ piece of 045 aluminum or 03 gal. Cut corners to approach a circular shape.

Circuit Description

W.375 V^375


Note that holes must be accuralely positioned for proper alignment to R12, R19, and J1 on the assembly or printed circuit board.

Figure 26-4 Final blowup and fabrication

Electrical Pretest

To run a test on the system, follow these steps:

1. Turn the controls to “off,” plug in the HS30 headset, and insert a 9-volt battery. Connect a meter set to read 100 milliamperes across the switch pins of R19 and quickly read a current of around 20 milliamperes. Remove the meter and turn control pot R19 to the midway point.

Note a smooth, rushing sound in the headsets. Then turn on a computer or TV monitor, and adjust the R12 control until you hear a clear tone. Turn off the sound source and gently rub two fingers together, noting a distinct sound. Check the range of the controls for unwanted feedback or spurious signals.

The unit is now ready for final assembly. Note the test points and wave shapes shown in Fig­ure 26-2.

її cannot be stressed the importance of proper heat sinking of the pins 10 the transducer TD1 before attempting soldering. If you are in doubt, use a vwre nut or "slip on" pin connections Note the shorter pin is internally connected to the transducer case and connects to the ground side of the circuit You should measure a short circuii from this pm to the aluminum shell or ihe transducer is no good!


Circuit Description

You may use a 9-volt battery or 12 volts using an 8 AA pack that will fit into the HA1 handle. The 12 volts allow a small 8-ohm speaker to be used as it produces more volume.


Short pin is connected to shield e note in Fig. 26-4 before connecting to ihe pins on TD1.

Circuit Description

Figure 26-5 Chassis assembly with board connections

Circuit Description

R12 Tuning

Circuit Description

R19/S1 Volume

Power Note that J1 is wired for mono operation

2. Complete the final assembly, adding parabolic reflector PARA 12 for a greatly enhanced, per­formance, as shown in Figure 26-6.

Note that your unit may pick up strong magnetic fields, as it is not shielded for such. Performing the Doppler shift test, as noted earlier in these plans, eas­ily differentiates these fields.