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Introduction to the field intensity meter circuit principle

2017-08-11 09:01  
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This article is the summary of field intensity meter circuit  principle. Do you have any idea on the circuit and opinions, welcome to contact us. At the same time also hope that this article is helpful to you. The amateur intensity meter is small, portable, the bag rob units and is suitable for doors and Windows control. A complementary transistors to connect as a kind of efficient oscillator, direct drive a small horn. Lower part of the number and 3 v battery power supply to make a very compact structure. Loudspeakers in the circuit can be any type, its size is limited, only through the box would contain it. A switch is unnecessary, because the standby current is less than 20 mu of a painting. The current consumer warning sound when about 100 ma. If the circuit is used as a package to rob, SW1 can be written as a 3.5 mm mono jack and a magnet with a 3.5 mm socket. Mono plug and its internal cause a short-circuit. Will connect the plug with the little rope, etc. Don't supply the circuit and the voltage is greater than 4.5 v: it won't work and Q2 may be damaged. In any case 3 v supply is one of the best compromise.

Parts:

R1____________330K   1/4W Resistor
R2____________100R   1/4W Resistor

C1_____________10nF   63V Polyester or Ceramic Capacitor
C2____________100μF   25V Electrolytic Capacitor

Q1____________BC547   45V 100mA NPN Transistor
Q2____________BC327   45V 800mA PNP Transistor

SW1____________Reed Switch and small magnet (See Notes)

SPKR___________8 Ohm Loudspeaker (See Notes)

B1_____________3V Battery (two A or AA cells wired in series etc.)

 


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