Cont. >> Photo Switch Circuit using 555 IC

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2 Νοε 2013 (πριν από 3 χρόνια και 7 μήνες)

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Seven Segment
Counter
Display Circuit

Mains failure alarm
circuit

Photo Switch
Circuit using
555
IC

Electronic toss
circuit

Two transistor
siren

Touch Switch
Circuit using NE
555

10
minute timer circuit

selective timer alarm

Seven Segment Counter
Display Circuit

Seven Segment Counter Display Circuit

Description


Here is the circuit diagram of a seven segment counter
based on the counter IC CD
4033
.This circuit can be used
in conjunction with various circuits where a counter to
display the progress


adds some more attraction.


IC

NE
555

is wired as an a stable
multivibrator

for
triggering the CD
4033
.For each pulse the out put of CD
4033
advances by one count . The output of CD
4033
is
displayed by the seven segment LED display LT
543
.Switch
S
1
is used to initiate the counting . Diode D
1
prevents the
risk of accidental polarity reversal.


Cont. >> Seven Segment Counter Display Circuit

Mains failure alarm
circuit

Mains failure alarm circuit


Description.


H
ere is a simple mains failure alarm circuit that produces an
alarm whenever the mains supply fails . Lot of such circuits are
available , but the peculiarity of this circuit is that it requires no
back up power source like a battery to power the alarm when the
mains is absent.


When there is mains supply the transistor Q
1
(BC
558
) will be
OFF and the capacitor C
1
will be charged . When the mains
supply fails the transistor Q
1
becomes ON and the capacitor C
1
discharges through the Q
1
to drive the buzzer to produce an
alarm . The capacitor C
2
is the filter capacitor for the bridge .
Diode D
2
prevents the discharge of the C
2
when mains fails . If
D
2
is not there ,the alarms will remain silent for a time capacitor
C
2
to fully discharge after the power failure.


Cont. >> Mains failure alarm circuit


Cont. >> Mains failure alarm circuit


Notes



T
1


can be


a
230
V primary


6
V
secondary


500
mA


transformer.


B
1
can be a
1
A
bridge.You

can make the same using
four
1
N
4007
diodes.


All capacitors are rated
25
V.


You can use any general purpose PNP transistor (like
BC
158
,BC
177


etc) as Q
1
.


Photo Switch Circuit using
555
IC

Photo Switch Circuit using
555
IC

Description


This is a simple photo switch suitable for home and industrial
purpose . The circuit switches on a relay when the light intensity
falling on the sensor crosses the set limit.


The circuit is based on a

NE
555

and two transistors for driving
the relay . The

resistor

R
1


is adjusted such a way that under
normal condition the voltage across the LDR is less than
1
/
3
the
supply voltage . In this condition output of IC is high .This
makes transistor Q
1
on .Transistor Q
2

s base is connected to
collector of Q
1
.So


Q
2
will be off keeping the relay de energized .
When light falls the voltage across LDR rises above
2
/
3
Vcc

.This
makes the output of IC go high making the relay to energized .
The result we get a relay that operates according to the intensity
of light falling on the LDR.


Cont. >> Photo Switch Circuit using
555
IC

Notes .


Assemble the circuit on a good quality PCB or common board.


To setup the circuit switch on power supply , connect a
multimeter

across LDR and adjust R
1
so that voltage across


LDR is just below
1
/
3
supply voltage . Ensure that relay is off in this condition . If not reduce
voltage across LDR further more by adjusting R
1
to make relay off.


Now cover the top of LDR using a black paper and see the relay gets
activated . If not, make further adjustments with R
1
.Nothing to care
after some trial and error you will get the correct set
piont

of R
1
where
the circuit works . This circuit


is nothing great , but some simple basics
. I have tested this and got good results . So no problem .Just proceed.


If there is some chattering in the relay , that may be because off the
difference between the turning on and turning off voltages . This can
be avoided by connecting a resistor whose value is equal to
1
/
2
the
resistance of LDR at illuminated condition.


Cont. >> Photo Switch Circuit using
555
IC

Electronic toss circuit

Electronic toss circuit

Description.


The circuit given here can be used for tossing head or tail. There
are many games in which a tossing is required to start and this
circuit can be used in all such instances.


The circuit uses two ICs NE
555
timer (IC
1
) and
74
LS
76
dual JK
flip flop (IC
2
).The IC
1
is wired as an a stable multi vibrator
operating at
10
Hz.The output of IC
1
is inverted by using the
transistor Q
1
.The collector of Q
1
is connected to the pin
1
of IC
2
via the push button switch S
1
.The IC
2
is wired in toggle mode.
When push button S
1
is pressed the output pins
14
and
15
of IC
2
starts toggling in state. The LEDs connected to these pins also
toggles (Since the frequency of toggling is
10
Hz, we feel both
LEDs glowing).When push button S
1
is released either one of the
LED remains ON indicating the head or tail.


Cont. >> Electronic toss circuit

Notes.


The circuit can be powered from
5
V DC.


Switch S
1
is a push button switch.


The ICs must be mounted on holders.


The circuit can be assembled on a general purpose
PCB.


Cont. >> Electronic toss circuit

Two transistor siren


Two transistor siren

Description.


Here is the circuit diagram of a simple two transistor alarm
circuit that can be operated from a
9
V PP
3
battery. Here
the two transistors are wired to form an oscillator whose
frequency increases when switch S
2
is pressed and
decreases when S
2
is released. In order to attain this the
base of Q
1
is biased from an RC circuit comprising of R
2
and C
1
.When S
2
is pressed C
1
is charged through the
resistor R
2
.As the voltage across the C
1
increases the time
constant decreases and this results in an increases in the
frequency. When S
2
is released capacitor discharges and
the frequency of the tone decreases. The sound heard from
the speaker will be almost like that of a siren.



cont. >>Two transistor siren

Notes.


The circuit can be assembled on a Vero board.


Use a
9
V PP
3
battery for powering the circuit.


Switch S
2
can be a miniature push button switch.


The type no of transistors are not very significant here.



cont. >>Two transistor siren

Touch Switch Circuit
using NE
555

Touch Switch Circuit using NE
555


Description


This is the circuit diagram of a small touch plate controller using IC

NE
555

.This circuit is ideally useful for making touch
operated

doorbells
,

buzzers

, toys etc which when touched on the touch
plate operates the

relay

for a preset time and the turns off automatically.


This circuit is realized by utilizing the high input impedance of trigger pin of
the
555
IC . When


the IC is triggered by the induced voltage of human body
the output goes high for a time determined by R
1
and C
1
.The transistor is
used to drive the relay . The relay contacts can be used to drive the load
like bell, motor , lights etc.

Notes.


To make the touch plate cut a
1
square cm thin metal sheet.


To setup the circuit connect to

power supply

and


adjust R
1
while keeping touching on the touch plate . Stop at the point
where relay activates . If relay is in the activated state initially
then do the same until the relay is deactivated.


Cont. >> Touch Switch Circuit using NE
555


10
minute timer circuit

10
minute timer circuit


Description.


When ever you need to get an alarm or intimation after ten
minutes ,the circuit shown below can be
used.The

circuit is
nothing but


a
monostable

multivibrator

based on IC NE
555
.When ever you press the reset push button the green
LED D
1
glows after
10
minutes.

Notes.


Assemble the circuit on a good quality PCB or common
board.


The time duration can be set by varying the POT R
5
.


The switch S
1
can be a push button switch.


The IC
1
must be mounted on an IC base.


Cont. >>
10
minute timer circuit


selective timer alarm

selective timer alarm


Description
.


A timer circuit using IC
4060
is given here. The IC
4060
is a
14
stage binary
counter with a built
-
in oscillator.R
2
, R
7
, C
1
are the components that determine
the frequency of the oscillator and the outputs will become high one after other
and only one at a time. The last five outputs are only used here. The high pulses
from the outputs are used to trigger the NE
555
IC. Here NE
555
is wired as a
monostable

multivibrator
. The buzzer will produce the alarm when the output
of IC
2
goes high. The duration of the alarm depends on the components C
3
and R
5
.The duration can be adjusted by varying the value of C
3
.The alarm will
automatically turn OFF after the predetermined time. The trigger pin of IC
2
will be normally positive. When the Q
1
is forward biased by the positive pulse
at its base from IC
1
, the capacitor C
2
becomes charged and reduces the voltage
at trigger pin of IC
2
.This triggers the IC . When the capacitor is fully charged
the pin
2
becomes again positive.

The maximum duration from timer IC
4060
will be at pin
3
. The times decrease
by half in the pins
2
,
3
,
15
, and
13
respectively. The timer duration can be varied
by varying the capacitor C
1
.


Cont.>> selective timer alarm


Notes.


Use
6
V DC for powering the circuit.


Assemble the circuit on a good quality PCB.


Mount the ICs on holders.


The switch S
2
can be a single pole five throw rotary
switch.


The switch S
1
can be a push button switch.


S
1
is used to reset the timer.


S
2
is used to select the alarm time.


R
7
can be used for the fine adjustment of alarm time

Cont.>> selective timer alarm


Thanks