Mitsubishi Electric MUX-25TV - E1 User Manual download pdf (Page 49)

560;

C6'

H5'

2N5259

2N5269

NOTE:

'See text.

T1'

R2 C5

1N4004

470K

0.1,F

1N4004

,-.

20 N

209

I2009F

47K

2N2646

39RF

T2'I

FT1

SCR

MCR 100

N G A

SCHI

BOTTOM

VIEW

BOTTOM

VIEW

100

Fig. 1. This is the

project's overall

schematic diagram.

the winding

between

terminals 1 and

2. To

generate repetitive

flashes,

uni-

junction

transistor Q3 is

connected

as a

very -low-

frequency

relaxation

oscillator, via

C2,

and R4.

When

power is

applied

to the cir-

cuit and C2

charges to about half

the

battery

voltage,

Q3 suddenly

con-

ducts from

emitter (E) to

base I (B1).

This

dumps the

charge stored in

into

R4.

Capacitor C2 then

begins to

recharge,

and the process is repeated

once every 4

or 5 seconds,

as deter-

mined

by the R3 /C2

time

constant.

capacitive

-discharge

circuit is

made

up of

T2,

and Q4. Charging

of C5 to 250 volts

is accomplished

through

R2. Though T2

also con-

nected

to C5,

current can't flow in

the transformer

primary

because sili-

con- controlled rectifier

SCRI isn't

yet triggered into

conduction.

When

switches on,

the

regu-

lating voltage

spike that

appears

across R4 is

also applied

to the gate

(G)

terminal of SCRI. This

causes

the SCR to switch

on and suddenly

apply the

250 volts

stored in

C5 to

T2's

primary. The C5/T2 primary

(LC)

circuit dissipates

the charge as

burst of oscillation.

Since

has

a step -up ratio,

when

the charge on CS is

being dissipated,

the

energy at the secondary is

least

4000 volts.

This

potential, applied to

the trigger

electrode of FTI,

causes

the flashtube

to conduct,

allowing

most

of the

energy stored in C3 and

to be converted into heat

and

light.

It's this

conversion that pro-

duces the flash. The

cycle

repeats

for

long

as power

switch SI

closed

and there's sufficient voltage in BI

excite the circuit. The repetition rate

is 4

or 5 seconds.

Construction

Begin

construction by

fabricating

transformer

Ti (see

box

for

details).

Once the transformer

is ready, wire

PARTS LIST

Semiconductors

D1,D2- 1N4004 rectifier diode

Ql,Q2- 2N5296

or similar transistor

Q3-

2N2646

or similar unijt.nction

transistor

SCR

1 -MCR

100 -5 (Motorola) or simi-

lar silicon -controlled

rectifier

Capacitors

CI- 20C -µF, 15

-volt electrolytic

C2- 39 -MF, 10-volt

electrolytic

C3,C4- 20 -$F, I50

-volt

electrolytic

C5- 0.1 -PF,

300 -volt

Mylar

or m.ramic

C6 -0.22-

0.0047 -µF,

100 -volt disc

(see text)

Resistors ('Vs

-watt,

10% tolerance)

-56C

ohms

R2- 47C,000

ohms

R3-

47,100

ohms

R4 -10C

ohms

R5 -68 ohms (12

-volt units only -see

text)

M'Iscellaieous

FTI -250 -volt flashtube

(Radio Shack

No. 2'2 -1145

or similar -see text)

-Sps slide

or toggle switch

TI- Hand -wound

transforma on

TDK

P22.5 Z52H pot core

(see

text)

T2- Trigger

transformer

(Triad

No.

-10 or similar) Printed-circuit

board or

perforated

board andsokler

posts; transistor sockets; heavy-duty

stranded hookup wire

for power

leads;

suitable enclosure; hookup

wire; No.

and

No.

36 enameled

wire; machire hardware; solder; etc.

Node: T1-e flashcube

and trigger

trans-

former

are available as Cat. No. 32SO430

from I-i Tek Sales, I I9R Foster

S..,

Pea-

body, MA 01961. The following ayeasail-

able from

A. Caristi,

White

Poid

ltd.,

Waldwick,

NJ 07463:

pc board

fo-

75;

pot core

/bcbtin

for

T1 for $6.75; 2N21,46

transistor

and MCR 100 -5 SCR fcr

$:.75

each. Add 51.30 S&H.

the circuit on

either

a printed -

circuit

board or on perforated

board

using

solder posts. The pc board

(see

Fig. 2

for the actual -size etching

-and-

drilling

guide) is recommended if you

want

very

compact project. Other

than

this, since there's

nothing

critical

with

regard to layout, either

method

can be

used with

success.

If you use a pc

board,

refer to the

diagram in Fig. 2 for

component

Say

You

Saw It In Modern Electronics

April 1986

/ MODERN ELECTRONICS

1 2 ... 44 45 46 47 48 49 50 51 52 53 54 ... 83 84

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Mitsubishi Electric MUX-25TV - E1 User Manual Page 49

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