AnCXT_met_20160526

13.

LM393 TL082 ,

LM393.

,

– .

.

– ( ) .

. U(+)

U(–), U

. U(+) < U(–), ,

, U .

: U U(–) U(+),

. ,

, , +/–U .

, U(+) U(–)

, U(–) U(–) –

. ,

:

+/–U .

(

) . ,

1-2 . ,

, . | U(+) – U(–)| < 0.7 . ,

, 0.7 . ,

( ,

).

, , ,

– . ,

» – ,

, ,

, , .

,

(==).

, .

. ,

, .

, , .

–U ,

, .

.

. ( ),

–U , – .

—101 —

+U ,

, «pull-up ».

, :

U(+) < U(–),U = –U ;

U(+) > U(–),U = +U .

U(+) = U(–) :

.

(

). (U ).

–U +U , . ,

, . –U = GND, ,

, .

,

( . . 95).

. 95. ( ) ( )

. ,

, ( . . 96).

, R .

U	U
+U	+U
U	U
–U	–U
U	U

. 96. ( )

( )

– ,

( ), .

,

. . ,

220 ,

, .

—102 —

,

,

U , , ,

. , ,

50 50%. ,

. 96, . ,

20 U

, U U ( . . 97).

U

t

U

t

. 97.

U

, ,

( ).

. :

–U +U , – .

. ,

. 97, , , .

,

« » .

,

.

( . 98, ) +/–U

, ).

. 98. ( ),

U = +U ( ), U = –U ( )

— 103 —

( . 95, )

U(+) U , R2 R1

U(+) , : +U , –U .

, (R1+R2) >> R , R

. U .

+U ,

U(+), –U ,

. 98, . ,	R1 R2,
I = (U – U ) / (R1	+ R2). R1
R1 (U – U ) / (R1 + R2). U
. ,

–U U = U(+) =
(117)			( )
U 1 :		= +		=		=

–U ,

U(+), +U ( .

98, ) I = (U –

(–U ))

/ (R1

+ R2).

R1

R1 (U +

U ) / (R1

+

R2),

(118)

( )

(U = +U )

U

= U(+)

= U 2

,

=

=

=

:

U

U

+U

U

–U

U 2

U

U 1

. 99.

(119)

,

U

1,2

U :

+ )

(120)

=

=

= (

=

=

= ( )

(119) (120),

. . 99) U .

U

= 2

=

100%

= (U 1 – U 2). ,

(121)

,

.

+U , GND (

),

U

–

(GND…+U ),

(121)

(122)

=

100%.

— 104 —

( . . 100). , , , U

U .

. ,

(

U U = +U ). ,

, ,

, (R1 + R2). ,

U .

U	U
+U
		U
–U
U 2 U		U 1

. 100. ( )

( )

.

, U 1. ,

–U ,

																						U =					U 1,
:
	=	) – ,																							1			2
						(123)																			.
												R R U =
															(				)
U 1 . :
	+U ,
																+						( )
	=		(124)																					U
								2
			– ,
			(125)																										,
											.
U						= U				. (123) (124)																,				:
						1		(										)				= 2
	U = (U						– U				= 2										= 100%
												2), :
						(126)																		.
	, (GND,
												(127)					=				100%.
+U )

— 105 —

– .

,

,

. , . 98, ,

, C R ,

R , :

. 101.

U

, U

.

( ). , ,

, U = +U –U ,

, UC. ,

, U = +U , . .

U U 1 ( . . 99 U = 0),

U =–U U 2.

,

U . , ,

RC, ,

, . (U 1 – U 2) , , U .

,

.

, .
, RC- ,
	(t)				m
«			»,
						(t)
					( . (66)-(68)).			,
, U ,									.

U C . 101

, , – +/–U ,

U = 0:

— 106 —

–U	U +U
+U
–U			U
	U			–U		+U
t			U				U
							t
t							t
–U U	t	U	+U			t
2		1

. 102.

, t ( ),

U = +U ( . . 102)

U 2 U 1

+U , .

( ) =

(

)

+

< 0 > 0

(128)

,

,

.

U

= |2 U 1(2)|, (128)

(129)

( )

=

+

C

t ,

U

U 1 = U

/

2.

, t = t

= +

+

=

(130)

:

(131)

=

=

=

=

,

,

:

(131),

=

t :

(132)

=

RC

= 0.7 RC.

,

(121)

= , (132)

, 2U :

— 107 —

(133)
,	= =								,	= 1 +
T = 2 t = 2 t = 1/f,				(134)	= 2 1 +

(+U , –U ) U = 0,

(U , GND) U = U / 2.

,

, R1 R2,

2 U . , ,

, ,

, .

, .

2 U , UC U 1(2) .

,

, .

. , .

10-20% .

— 108 —

1., . 103.

, +/–10 .

LM393 – TL082.

, DL3 ( ) , DL2 – , DL1

–.

. 103.

,

. 2 ,

, , (20–2) / R = 8 DL1,2 4 DL3.

, ,

, ,

R1-R4.

,					U DA1.1,
	20		,			,
DA1.2 DA		.1:					= 20 10 =
=		10 = 4 = 20 10 = 0

5-6 0.5 , .

. , .

( ), ( ) , , .

.

3.+U –U

.

—109 —

4.1 , 2 –

DA1.1, DA1.2 DA2.1,

U 1-3

, –U .

LM393 :

. 104.

VT1 , BZ1

.

6., +/-10

100 .

.

+U –U .

7.1 C, 2

–, 3 – , ,

( ) ,

2 3,

1. UC, U , U 1(2).

8.,

. ,

.

1 2.

. X Y

, 2-3

.

9.+U –U ,

f U .

(132) , f = 1 / T = 1 / (2 t ). 10.

p-n-p ,

, .

,

.

( R )

. VT1

,

.

— 110 —