Avt Avt1460 User manual

Twilight switch

Twilight switch automatically switches on and

off the lighting of your home, garden or other

place. When it gets dark, the device switches on

the output relay. The twilight switch is equipped

with circuitry that eliminates the possibility of

oscillation if the illumination level is at the

operating threshold.

Specifications

• photo resistor as a light sensor

lighting is at the operating threshold

• power supply: 12-15V DC

• hysteresis eliminates oscillations when the

• adjustable sensitivity

• active status indication with LED

• output relay with contacts 230V AC, 8A

Schematic of the twilight switch is shown in

Figure 1. It is based on the TL071 operating

amplifier working as a comparator. The TL071

compares the voltage from the potentiometer

PR1 to the voltage from a resistive divider made

up of a resistor R3 and a photoresistor. The

decrease in the intensity of light incident on the

photoresistor causes an increase in the voltage

on the pin 2 of the operational amplifier U1. If

the voltage on the pin 2 will be higher than the

voltage on the pin 3, the amplifier output

voltage appears, causing conduction of the

transistor T1 and switching on the relay RL1.

The PR1 potentiometer allows for adjusting the

sensitivity threshold over a wide range. The C3

capacitor eliminates the possibility of oscillation

if the illumination level is at the operating

threshold. Relay contacts are switched on at

dusk and off at dawn. Using the changeover

contacts can reverse the operation of the

device. The high load capacity of the relay

contacts enables the switch to be used in a

variety of applications. The switch can be

battery.

DIFFICULTY

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Functional description

AVT 1460

Twilight switch

http://bit.ly/2JYmoFM

PDF

DOWNLOAD

The assembly is typical and should not cause

the problems. It runs in standard way starting

from the smallest components and ending with

the largest ones.

The device assembled from the tested

components does not require any adjustment

and operates immediately after the power is

turned on. The twilight switch will not only be

used for lighting control but also in

photography, modeling and other applications.

In the active mode twilight switch consumes a

current of approximately 100mA.

Figure 1. Schematic diagram

AVT 1460

Twilight switch

DIFFICULTY

LEVEL

Assembly and test

TL081P

1N4148 1N4148

1N4007

V+ V+ V+

GND

BC558

US1

PR1

100k

100nF

D2 D3

LED1

150k

47k 1k

R3 R4

330k

100uF

62k

1,5k

PK1

C1C2

220uF

+ 12V -

Figure 2. Connection example

Start off by soldering the printed circuit elements in order from smallest to largest. The unit assembled

flawlessly, using the supplied components will operate immediately after switching on the power supply.

Photoresistor

Component list

R2: ................47kΩ (yellow-red-orange-gold)

R3: ................62kΩ (blue-red-orange-gold)

Resistors:

R1: .................150kΩ (brown-green-yellow-gold)

R4: ................330kΩ (orange-orange-yellow-gold)

R6: ................1kΩ (brown-black-red-gold)

FR: ................photoresistor

R5: ................1,5kΩ (brown-green-red-gold)

PR1: .............trimmer potentiometer 100kΩ

D2, D3:.........1N4148 or similar !

T1:..................BC557 (BC558) !

Others:

X2: .................3-pin terminal block connector

Capacitors:

C3: .................100µF !

C2: .................220µF !

U1:.................TL081 (TL061, TL071)

C1: .................100nF (marked as 104)

PK1:...............relay

X1, X3:..........2-pin terminal block connector

D1:.................1N4007 or similar !

Semiconductors:

D4:.................LED diode

DIFFICULTY

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Assembly in 4 steps

Solder resistors R1-R6 and diodes D1-D3

Solder capacitors C2, C3, relay PK1, insert chip

into socket, screw the photoresistor to X3

Solder IC soket, capacitor C1 and trimmer

potentiometer PR1

Solder transistor T1, LED diode and connectors

ZOOM

AVT 1460 Twilight switch

While assembling the components marked

with an exclamation mark attention should

be paid to their polarity. Symbols of the

components on the PCB as well as photos of

assembled sets may come in useful. To access high-

resolution images, download the PDF file.

PDF DOWNLOAD

http://bit.ly/2JYmoFM

DIFFICULTY

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AVT 1460

Twilight switch

Notes

Educational Electronics Kits are intended for educational and demonstration purposes only. They are not intended

for use in commercial applications. If they are used in such applications the purchaser assumes all responsibility for

ensuring compliance with all local laws. In addition, they cannot be used as a part of life support systems, or systems

that for use as or as a part of life support systems, or systems that might create a hazardous situation of any kind.

Thank you for purchasing AVT product. Please take your time to read carefully the important information below

concering use of this product.

• Never exceed the limits or ratings listed in the 'Specifications' section at the this user guide.

• Battery or wall-adaptor are safe devices. They do not require special attention unless main voltage is connected to

an output e.g. a relay.

• If the kit is used to switch currents greater than 24V it is necessary to have the installation and performed by a

trained professional authorized for such work. The kit may only be used in such application if it was installed in a safe

to touch enclosure.

• The product itself and all parts thereof (including packing material) are not suitable toys for childern! (choking

hazard, risk of electric shock, ...)

• If the kit is used in schools or educational facilities or similar institutions the operation must be supervised by

trained and authorized staff.

Failures in modern electronic component are very rare as 95% of non-working kits are due to poor soldering or

components placed in the wrong location or orientation so please check your work carefully.

AVT SPV reserves the right to make changes without prior notice.

Assembly and connection of the device not in accordance with the instructions, unauthorized modification of components and any structural modifications may cause

damage to the device and endanger the person using it. In this case, the manufacturer and its authorized representatives shall not be liable for any damages arising directly

or indirectly from the use or malfunction of the product.

This symbol means do not dispose of your

product with your other household waste.

Instead, you should protect human health

and the environment by handing over your

waste equipment to a designated collection

point for the recycling of waste electrical

and electronic equipment.

Leszczynowa 11 Street,

03-197 Warsaw, Poland

http://avtkits.com/

AVT SPV Sp. z o.o.