Memorex CP8 TURBO UNIVERSAL REMOTE CONTROL Uživatelský manuál stáhnout pdf (Strana 86)

100

B1 ¡

+3V

2N2222

270L,

POS.

1 +1

TERMINAL

PROTECTED

CIRCUIT

NEG

TERMINAL

PROTECTED CIRCUIT

Fig. 5 -The current limiter is

ad-

justable

from

about

0.5 to 8 mA

and can

be used with

circuits having

supplies

ranging

30- volts. If a more

bullish circuit is required,

replace

the

2N2222

with a 2N3055

and R1 with

10 -ohm, 1 -watt

resistor

and

with a

500 -ohm, 2 -watt potentiometer.

That

allows

a maximum

current

of about 200

milliamps,

and a minimum

of 5 mA

PARTS

LIST FOR THE

CURRENT LIMITER

B1 -9

-volt transistor battery

Q1- 2N2222 general

-purpose NPN

silicon transistor

R1-

270

-ohm

1/2-watt,

resistor

-5,000

-ohm potentiometer

S1-

Single -pole single

-throw

switch

Printed

circuit

perfboard

materials,

enclosure,

sockets,

battery,

wire,

solder, hardware,

etc

project and its power source (DC only),

you can keep the smoke from getting in

your

eyes, and

Murphy at bay.

The

circuit's current- limiting range is

adjustable from about 0.5 to 8 milli -

amps and can be used with circuits hav-

ing

supplies

ranging

up to 30-

volts.

If a

more bullish circuit is required,

replace

the 2N2222 with a 2N3055 and R1 with

-ohm, 1 -watt resistor and R2

with

500 -ohm, 2 -watt potentiometer. That

allows a maximum

current of about 200

milliamps,

and a minimum of 5 milli -

amps.

When

setting up

the circuit, connect

the current limiter in

series

with

a cur-

rent meter and connect that combina-

tion across

the power

source

that's to be

used. Adjust R1 for the maximum cur-

rent that you

want

to pass through your

circuit.

OK get in there and give Mur-

phy a kick for me.

Transistor Checker

The

circuit

in Fig. 6 is for

those of us

that never throw out any

three - legged

device no matter how

"used" it might

appear. If you

have doubts about

number of your

junkbox transistors,

then build

this simple go

/no -go tester

and at least separate

the good ones

from

HIGH

GAIN

LOW

GAIN

470K

LEDI

47K

TEST

SOCKET

I +9V

Fig.

6 -The

transistor

checker gives a good indication

as to value

most NPN

and PNP low -power

silicon and older germanium transistors.

PARTS

LIST

FOR THE

TRANSISTOR TESTER

-9

-volt battery

LED1

-Jumbo light-

emitting

diode

R1-470

-ohm

1/2 -watt,

resistor

R2-47,000-ohm 1/2-watt, 5%

resistor

R3 -1000 -ohm 1/2 -watt, 5%

resistor

S1- S3-

Normally

-open

SPST

pushbutton switch

S4- Double -pole, double -throw

switch

Perfboard

materials, enclosure,

tran-

sistor socket,

wire,

solder,

hardware,

etc.

the bad. The circuit gives a good indica-

tion as to

value of most NPN and PNP

low

-power

silicon and

older ger-

manium -type transistors.

LEDI indicates the relative condition

of the transistor under test.

With the

"suspect" in the test socket (TR) and

the PNP

/NPN switch,

S4,

the correct

position,

the LED should remain dark.

If it glows, it's

usually an

indication

that

the transistor is suffering from an inter-

nal

short, or at the

very least, that there

is high leakage between its emitter and

collector.

If LEDI is dark, press SI and a

medi-

um to a high -gain

transistor will cause

the LED

light at full brilliance. A

dim glow indicates

a lower gain figure.

Press

S2 and the LED

should glow at

full brilliance. If not, it could

mean that

the device is a

very-low gain

transistor

or that it's past retirement

age.

Another useful check to perform,

primarily

with

the older

germanium

type transistors, is the base -to-

collector

leakage -current test.

By closing S3 the

diode junction

between the transistor's

base and collector

is placed in series

PARTS LIST FOR THE

DIODE

SWITCHING CIRCUITS

FIG. 7

C1, C2-

0.27

-µF, 100

-WVDC

Mylar

capacitor

D1-1N914

small

-signal

silicon diode

R1, R2- 10,000

-ohm

' /2-watt,

re-

sistor

-See text

FIG.

C1-C3

0.27

-µF, 100

-WVDC

Mylar

capacitor

D1, D2 -1N914

small

-signal

silicon

diode

R1-

R3- 10.000

-ohm 1h -watt,

re-

sistor

S1, S2

-See text

FIG. 9

C1-C3 0.27 -p.F,

100

-WVDC

Mylar

capacitor

D1, D2 -1N914

small

-signal

silicon

diode

R1-

R3-

10,000

-ohm

1/2-watt,

resistor

Printed

circuit or perfboard materials,

enclosure, IC

sockets, battery,

wire,

solder, hardware,

etc.

with

R3, LEDI,

and the battery. If the

device has high leakage, the LED

glows. If it

glows a little more than

"dim," it's a good indication that the

transistor is defective.

Diode Switching

Circuits

Diodes are

useful

for

more duties

than just changing AC

DC. The cir-

cuit in Fig. 7 uses a silicon diode to

switch

audio from point "A" to point

"B" by applying a positive voltage

the bias circuit. The switching bias

volt-

age can come

from

mechanical

switch

or any logic output.

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