Rf signal detector

1. R.F. SIGNAL DETECTOR
MINI PROJECT
UNDER THE GUIDANCE OF
MR. KARTIK GOYAL SIR
By:-
 Samarjeet
(1774531003)
 Sudheer

2. CONTENT
 INTRODUCTION
 COMPONENT
 CIRCUIT DIAGRAM
 WORKING
 PCB DESIGN
 CONSTRUCTION AND TESTING

3. INTRODUCTION
• THIS SIMPLE RF SIGNAL DETECTOR CIRCUIT CAN BE USED
TO TRACE THE PRESENCE OF RF SIGNALS AND
ELECTROMAGNETIC NOISE IN YOUR RESIDENTIAL AREA,
OFFICE OR SHOP. IT CAN BE A USEFUL TOOL WHILE
TESTING OR DESIGNING RF CIRCUITS. IT CAN ALSO BE USED
TO DETECT ELECTRICAL NOISE IN YOUR PREMISES.

4. COMPONENT

5. CIRCUIT DIAGRAM
Fig. 1: Circuit of RF signal detector

6. WORKING
FIG. 1 SHOWS THE CIRCUIT OF RF SIGNAL DETECTOR. IT
CONSISTS OF A TELESCOPIC ANTENNA, INPUT PROTECTION
RESISTOR (R1), TWO DIODES (D1 AND D2), SELECTOR SWITCH
(S1), PRE-AMPLIFIER WITH A LOW-NOISE AND HIGH-GAIN
TRANSISTOR (T1), AND AUDIO AMPLIFIER IC LM386 (IC1).

7. Switch S1 is used to select between high and
low sensitivities of the circuit. When high
sensitivity is selected, gain of the transistor
stage with T1 is added to gain of IC LM386.
When low sensitivity is selected, gain of only IC
LM386 is used, which is around 20. In order to
keep the circuit simple and compact, no volume
control is included.

8. PCB DESIGN

9. CONSTRUCTION AND TESTING
NORMALLY, THE CIRCUIT DOES NOT NEED ANY
ADJUSTMENT. BUT IT IS PREFERABLE TO KEEP THE
COLLECTOR-EMITTER VOLTAGE OF T1 AROUND HALF
THE POWER SUPPLY VOLTAGE AND THE COLLECTOR
CURRENT AT LEAST 1 MA. THE PREFERRED POWER
SUPPLY RANGE IS 9-15 V DC. IF THE CIRCUIT
PRODUCES MOTOR BOATING NOISE WITH AC MAINS
ADAPTER, USE A BATTERY INSTEAD TO REDUCE THE
NOISE. THE CIRCUIT WORKS WELL WITH A SINGLE 9V
PP3 OR 6F22 TYPE BATTERY. YOU CAN USE YOUR MOBILE PHONE
AS THE RF SOURCE. DIAL ANY NUMBER AND PLACE THE PHONE NEAR THE
ANTENNA.