Memorex CP8 TURBO UNIVERSAL REMOTE CONTROL Manual de usuario descargar pdf (Pagina 27)

is that the circuit

has been

complicated

by the use

of a lot of

standard chips

instead

of simplified

with a computer

circuit

and

program.

It

all

depends

on your own

definition

of simple

and complicated.

A lot of comparisons

can be

made between

this circuit and

a computer circuit.

It uses manually

clocked

logic instead

of

a pre -written EPROM

program and

high -speed

clock. The

clocking

is done automatically

by the player

as he plays

the

game. Latches are

used to hold

data in memory,

with

the

latches controlled

by the

clocked logic,

rather than a CPU.

A

variety of decoders are

used to change

the output

from

decade counters

into a BCD

code to illuminate

the proper

LED chce spots.

In a computerized

circuit,

that

would be

done

with

a pm- programmed

EPROM.

The circuit

is an

example

of what can be

done using standard

chips as

opposed

to a

specialized computer

circuit.

How It Works

A schematic diagram

of

Computerized

Casino

Craps

is

shown in Fig.

1. Although the

circuit uses 18 chips,

it is not

overly complicated

or hard

to understand if

it is taken one

step at a time.

A new game is initiated

by pushing the

reset button,

which

causes

a positive

voltage to be applied

to pin 15 of U8

(a 4017

decade counter

/divider), causing

outputs I

to 9 to go low,

while the zero output

(pin 3) goes

high. That

high is applied

to U7a at

pin 15 (reset).

The reset signal

(from S2)

is also

applied

to pin

7 of U7b and pin

3 of U7c,

causing their

outputs to

go low. For

now,

we

can

say that

when the reset

button

is pressed,

all the outputs

of U7 go

low.

A hex Schmitt

trigger, U1,

is configured

as two

square -

wave

oscillators

( Ula/Ulb

and Ulf

/Ule),

whose frequencies,

are determined

by

C3/R29

and C4/R36,

respectively.

The

series/parallel combination

of R34/D3

and R29 connected

across Ula causes

a positive

voltage

to be

applied to pin

1,

inhibiting the oscillator.

The

combination

of R35/D8 con-

nected to

pin 13 of Ulf

performs the

same function

on the

other oscillator.

The outputs

of the oscillators

(Ula/Ulb and

Ule

/Ulf) are

fed to

the clock input of

the decade

counters, U3 and

U4,

respectively. When

ROLL (a single -pole,

double

-throw

push-

button) switch

SI is momentarily

depressed,

C2 charges

to

the

supply rail and

then slowly

discharges through

R37.

That

decaying

voltage is applied to pin

5 of Ulc

anc ph 9 Uld,

forcing

their outputs

low,

which reverse -biases

D5 and D6.

That allows

C3 and C4

to discharge

though. L

la and Ulf,

respectively, enabling

the two

oscillators.

The oscillators

continue to cycle,

as the

cl-arge on C2

decays.

When

the

charge on C2

reaches 50%

cf the

supply

voltage,

the

outputs of Ulc

and Ulc abruptly

go

high, for-

ward-

biasing

D5 and D6,

stopping the

oscilla_ori.

The use of

two

separate gates enhances

the random

-number

factor be-

cause

they shut off

at different times

(due to

varying internal

characteristics

of the gate).

The

outputs of Ulc and

Uld are applied

to U2a (%

of a

4081

2 -input

AND

gate)causing

its output .o

go high.

That high

is,

in turn,

fed to the

set input of U7d (%

of a

4043 quad, tri-state

NOR R/S latch) at

pin 12.

The output of U7d

is applied

to the

clock

input of U8 at pin

14, causing

t to advance

one

count.

When

Si,

Rocc -a single -pole,

double

-throw

pushbutton

switch -is depressed,

a positive

voltage is

applied

to pin

11 of

U7d

and to pin 5

of UIc and

pin 9 of

Uld, re

¡ding U7d

and

stopping the

oscillators. On

the next

roll, U7i again

sets and

U8 is advanced

to count

2, at

which time it

s cisabled

until

reset

again by pressing

S2.

31

1 2 ... 22 23 24 25 26 27 28 29 30 31 32 ... 99 100

Comentarios a estos manuales

Sin comentarios