WA

RN

ING

: This product contains chem

icals, including lead, know

n to the State of California to cause cancer, birth defects

and/or other reproductive harm.

W

ash hands after handling.

PO

Bo

x 5

01

V

ac

av

ille, C

A 9

56

96

US

A

1-7

07

-44

8-3

75

0

http

://ww

w.te

ch

kits.c

om

Part N

um

ber: R

FM

ET

ER

-MA

N

AS

SE

MB

LY

INS

TR

UC

TIO

NS

F

OR

[RFM

ET

ER

-KIT

]

RF

FIE

LD

ST

RE

NG

TH

M

ET

ER

KIT

Price : $5.00

Copyright 2004, LNS Technologies, Vacaville, CA. All rights reserved.

No part of this document may be reproduced in any form or by any means

without prior written permission from LNS Technologies.

RFM-MAN-0804 Printed in the USA.

DE

SCR

IPT

ION

T

his useful kit is a wide-band R

F detector that indicates R

F field strength in the 100K

Hz-500M

hz range at low

levels. The kit includes an etched &

drilled circuit board and all necessary components (except 9V

battery). It also com

es with a plastic case, antenna and an attractive analog m

eter.

The R

F pow

er reading is not linear and simply indicates the presence of R

F and its relative level. H

owever,

it makes a great B

UG

detector or you can use it to test the output of any RF

transmitter; including H

am

Radios, cordless telephones and even car alarm

transmitters! T

he circuit has an adjustable attenuator to handle everything from

low to high pow

er levels.

QU

ICK

AS

SE

MB

LY

INST

RU

CT

ION

S

Refer to C

omp

onen

t Placem

ent D

iagram (F

igure 1) for location

s and

polarities.

Refer to F

igure 3 for con

nectin

g other d

evices to PC

board

. S

tep 1: Insert and solder wire jum

per JP1 in place on P

C board.

Step 2: Insert and solder resistors R

1-R5.

Step 3: Insert and solder diodes D

1-D4, N

OT

E P

RO

PE

R P

OL

AR

ITY

. S

tep 4: Insert and solder 8-pin socket for U1, N

OT

E P

IN 1 L

OC

AT

ION

. S

tep 5: Insert and solder Inductor L1.

Step 6: Insert and solder capacitors C

1-C4.

Step 7: Insert and solder electrolytic capacitors C

5 & C

6, NO

TE

PR

OP

ER

PO

LA

RIT

Y.

Step 8: S

older 9V battery connector to P

C board, N

OT

E P

RO

PE

R W

IRE

CO

LO

RS

. S

tep 9: Solder 5 in. w

ire from term

inal lug to AN

T location on P

C board.

Step 10: A

ttach meter to plastic front panel, secure w

ith appropriate washers &

nuts. S

tep 11: Solder 4 in. w

ires from m

eter terminals to +

OU

T &

-OU

T on board, N

OT

E P

OL

AR

ITIE

S.

Step 12: S

older two 2.5 in. w

ires from sw

itch on potentiometer to S

1 location on PC

board. S

tep 13: Solder tw

o 4 in. wires from

potentiometer V

R1 to +

OU

T &

-OU

T locations on P

C board.

OU

T+

+V

S1

G

ANT

D1

10M

D2

L1

D4

100P

JP1

1K

100100K

10

0KU1

0.1

0.110

10

+

+

C1 C3

C5

C6

C4

R1

R2

R3

R4

R5

D3

OU

T-

C2

0.1

1N

34

9VBATTERY

VR

1/S1

FIG

UR

E 4

FIN

AL

AS

SE

MB

LY

ME

TR

IC

SC

RE

W

AN

TE

NN

A

KN

OB

PL

AS

TIC

E

NC

LO

SU

RE

RE

AR

o

f M

ET

ER

FIG

UR

E 3

INT

ER

CO

NN

EC

T D

IAG

RA

M

OU

T+

+V

S1

G

ANT

D1

10M

D2

L1

D4

100P

JP1

1K

100100K

10

0KU1

0.1

0.110

10

+

+

C1 C3

C5

C6

C4

R1R

2

R3

R4

R5

D3

OU

T-

C2

0.1

1N34

+ O

UT

- O

UT

RE

AR

o

f M

ET

ER

TE

RM

INA

L

LU

G

5 Inch

es

RE

D

WIR

E

BL

AC

K

WIR

E

4 In

ches

2.5 In

ches

VR

1 B

OT

TO

M

VIE

W

DE

TA

ILE

D A

SS

EM

BL

Y IN

ST

RU

CT

ION

S

Install D

iodes

D1 - 1N

34A G

ermanium

(silver) -><

- D

2-4 - 1N914 Signal ->

<-

Refer to F

igure 1 and the diagram

at right w

hen installing

the diodes.

D

iodes are

polarized and must be installed correctly in

order for your kit to work properly. E

ach diode has a black or w

hite band near one end of its body. T

he band indicates the cathode end and should be oriented according to the C

ompon

ent P

lacemen

t Diagram

. In

stall Ind

uctor

The inductor looks like a resistor but is w

ound with m

any loops of wire that are

clearly visible on the outside. Solder it in the location show

in Fig 1.

Install R

esistors

Orientation of a resistor doesn't m

atter, but the value does. If you need help identifying the value of a resistor, the parts list has the color bands listed. L

ocate resistor R1 (100 O

hms), install and solder it in place according to F

igure 1.

Then repeat the installation procedure w

ith each of the following resistors:

R2 - 1.0K

Ohm

Resistor, 1/4 W

att, 5%

R3,4 - 470 O

hm R

esistor, 1/4 Watt, 5%

R

5 - 10M O

hm R

esistor, 1/4 Watt, 5%

Diode

Schem

atic Sym

bol

Cath

ode

Com

ponentInstallation

Bend

PC

Board

Foil S

ide

Install C

eramic C

apacitors

Ceram

ic Capacitors - C

1,2,3,4

Using the P

arts List as a guide, locate the

100 pF (pico farad) capacitor, C1. T

hen refer to F

igure

1, install C1 and solder it into

place.

Orientation

is not

critical, since

ceramic capacitors are non-polarized. C

lip any excess w

ire from the bottom

of the PC

B.

Repeat the process w

ith the 0.1 uF (micro

farad) capacitors C2-C

4.

Install E

lectrolytic Cap

acitors

Electrolytic C

aps - C5 &

6 -><

-

Electrolytic capacitors are shaped like "cans" and usually have the value printed

on their wrapper. B

eing a polarized device, one side of the wrapper w

ill have a line of "m

inus" signs as arrows, pointing dow

n the side of the cap to the minus

leg. These caps m

ust be installed in the PC

B w

ith the plus leg (the unmarked leg)

of the cap in the hole marked "+

" on the component location draw

ing.

Using the P

arts L

ist as a guide, locate C5, a 10 M

FD

capacitor. Check the

orientation, then install and solder the C5 into place. R

epeat with capacitor C

6.

Non-polarized

Cera

mic

Capa

citor

Bottom

View

"Minus"

Leg

Ele

ctrolyticC

apacitor

D2, D3 & D4 = 1N4148

9 VDC

4.5 VDC

ANTENNA

D4

C3

0.1 MFD

C5

10 MFD

+

C6

10 MFD

+R5

10 MEG

R2

1K

R3100K

R4100K

C4

0.1 MFD

D1

1N34A

D2

D3

C1 100 pF

BAT

9 VDC

S1ON/OFF

VR1

1K

L1

2.5 mH

C2

0.1 MFD

R1

100 OHM

U1A TLC272

+

-

3

21

8

4

U1BTLC272

+

-

5

67

8

4

M1

50 uA

+

+

PA

RT

S L

IST

FO

R T

HE

RF

PO

WE

R M

ET

ER

KIT

RESISTORS

R1 .......... 100 Ohm, (Brown, Black, Brown, Gold)

R2 .......... 1.0K Ohm, (Brown, Black, Red, Gold)

R3,4 ........ 100K Ohm, (Brown, Black, Yellow,

Gold)

R5 .......... 10M Ohm, (Brown, Black, Blue, Gold)

VR1 ......... 1.0K Ohm, Panel Mount Potentiometer

with ON/OFF Switch.

CAPACITORS

C1 .......... 100 pF, 50V, Ceramic

C2-4 ........ 0.1 uF, 50V, Monolithic or Ceramic

-><- C5,6 ......... 10 uF, 16V, Electrolytic

SEMICONDUCTORS

-><- U1 .......... TLC272CP, Dual Op-Amp IC

-><- D1 .......... 1N34A Germanium Diode

-><- D2-4 ........ 1N914 or 1N4148 Signal Diode

MISCELLANEOUS ITEMS

L1 ........Inductor, 2.5 mH, Axial

JP1 ........Wire Jumper, 0.6 inch long

-><- M1 ........50 uA Meter, Panel Mount

ANTENNA ......8 inch Metal Antenna

PCB ........Printed Circuit Board (RFM0997)

-><- U1 ........8 Pin IC Socket

-><- BAT ........9V Battery Connector

........Solder Terminal Lug

........Knob for Potentiometer VR1

........Plastic Enclosure & Front Panel

........(4) 1/4” Threaded Hex Spacers

........(4) #4-40 1/4” Screws

........(4) #4-40 Nuts

........(1) M3 Metric Screw for Antenna

........24 ga. Stranded Hookup Wire

NOTE: -><- Indicates a polarized component or device.

Install IC

U

1 - TL

C272C

P Dual O

p-Am

p -><

-

First, inspect the 8-pin IC

, U1 [T

LC

272] WH

ILE

IT

IS

S

TIL

L

IN

TH

E

BL

AC

K F

OA

M. N

otice the notch in one end that will identify pin 1. B

efore rem

oving the IC from

its protective foam, rem

ove static electricity from your

body by grounding yourself by touching a water pipe or m

etal appliance.

The draw

ing below show

s a typical IC and its identifying features:

Attach

Poten

tiometer an

d O

N/O

FF

Sw

itch

VR

1 & S1 - 100K

Ohm

Potentiom

eter with S

witch

Cut three 4-inch pieces of 24 gauge stranded hookup w

ire and solder the wires to

the terminals of R

5 as shown in the diagram

below. T

hen cut two 2.5-inch pieces

of 24 gauge stranded hookup wire and solder the w

ires to the outside (switch)

terminals.

Next, refer to F

igure 3 for details

of connecting the three wires from

the

potentiometer

to the

printed circuit board. S

older the wires to

the PC

board as shown.

Refer again to F

igure 3 and attach the tw

o wires from

S1 to the PC

board as show

n.

4.0

" Long

VR1 &

S1

Potentiom

eter &

Sw

itch

2.5

" Long

Sold

erHere

Dot id

entifie

s pin

1

A n

otch

in o

ne e

nd

may id

entify th

e to

pof th

e IC

. Pin

1 is

the to

p le

ft pin

.End V

iew

Inte

gra

ted C

ircuit

(IC)

Mou

nt PC

Board

in Case

Mount the P

C board in the bottom

half of the plastic case with tw

o (#4 x 1/4") self tapping screw

s. Mount the potentiom

eter on the plastic case by inserting it into the hole and attaching the m

etal nut. You need to bend or rem

ove the small m

etal tab sticking up from

the potentiometer body so that it w

ill not interfere with

assembly.

FIN

AL

AS

SE

MB

LY

S

older 4 in. wires from

meter term

inals to +O

UT

& -O

UT

on PC board, N

OT

E

PO

LA

RIT

IES

. Install antenna as shown in F

ig 3 with term

inal lug touching antenna, secure w

ith metric screw

. Connect a 9V

battery to the battery connector &

place battery in enclosure. Attach plastic front panel (w

ith meter attached) to

enclosure using 4 screws.

OP

ER

AT

ION

N

ote: Diode D

1 is affected by ambient light. T

he circuit must be placed inside the

plastic enclosure away from

light before performing any tests or adjustm

ents on this circuit. T

urn the RF

meter O

N and set V

R1 to approxim

ately 1/2 of its rotation. The

meter needle should m

ove slightly. Bring the antenna near a broadcasting R

F

source (Ham

radio, cordless phone, car alarm transm

itter, etc). The m

eter should m

ove in response to the RF field. If the R

F signal is strong enough to m

ake the m

eter go off scale, you can adjust VR

1 for a better reading. T

his project is a handy way to test the output of a transm

itter to verify that it is w

orking. You can also use the R

F field m

eter to “sweep” a room

for hidden transm

itter “bugs”. Be sure to shut the unit O

FF

when not in use to conserve the

battery.

#4-4

0 x 1/4

" Screw

#4 H

ex N

ut

Enclo

sure B

otto

m

1/4" S

tandoff

PC B

oard

OUT+

+V S1G

ANT

D1

10MD2

L1

D4

100P

JP1

1K

100100K

100K

U1

0.1

0.110

10

+

+

C1

C3

C5

C6

C4

R1R2

R3R4

R5

D3

OUT-

C2 0.1

1N34

FIG

UR

E 1

CO

MP

ON

EN

T P

LA

CE

ME

NT

DIA

GR

AM