Avt 1820 User manual

Specifications

• two operating modes: seconds and minutes

Cyclic timer circuit with programmable relay ON

time and relay OFF time. It can operate in two

modes - seconds and minutes with a setting range

of 1 to 99. • time setting from 1÷99 in 1-step increments

• board size: 95×37 mm

displays

• operating status indicated on two switchable LED

• output circuit - relay NC / NO contacts

• supply: 12 VDC

Circuit description

Cyclic Timer

The LED ON jumper, or rather the absence of it, allows

the displays to be switched off for the duration of the

circuit operation. For setting purposes, the system is

equipped with 2 buttons labelled S1 and S2. Signals

from the buttons are routed to ports PB0 and PB1 -

the active level is logical '0'. Mounting diagram of the

timer is shown in Figure 2, it is mounted on

Electrical diagram of the timer is shown in Figure 1.

The device must be supplied with 12 VDC fed to the

ZAS connector. This can be any 12 V power supply

with a current capacity of not less than 200 mA. The

U1 stabiliser provides the +5 V voltage and capacitors

C1...C4 ensure its proper filtration. Operation of the

device is controlled by an Attiny26 microcontroller

timed by an internal clock signal. Status of the unit is

shown on a dual seven-segment display with a

common anode. The cathodes of the 2-digit

multiplexed LED display are connected via current-

limiting resistors R5-R12 to ports PA0-PA7. The role of

the keys that switch on the power supply to the

displays is performed by transistors T1 and T2,

controlled from ports PB3 and PB4.

a small, double-sided printed circuit board measuring

36 mm×94 mm, using through-hole components.

Assembly is typical and should not cause any

problems, and a system assembled from working

components will work correctly straight away. To

program the relay OFF time, press and hold the S1

button for approximately 3 seconds. After a while, the

lower segments of the display will start flashing. You

can now release the button and using the S1 and S2

buttons, increase or decrease the flashing value shown

on the display. Once the required time has been set,

press and hold the S1 button again. To set the relay

ON time, press and hold the S2 button, this will be

signalled by the upper segments of the displays

AVT 1820

ASSEMBLY DIFFICULTY

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Fig. 1 Schematic diagram

You should still remember to set the time unit with

the jumper in the SEK or MIN position. After these

steps, the device is ready for operation and the

activation of the output is signalled by the lighting of

a dot next to the unity digit. The displays can be

switched off for the duration of the unit operation by

removing the LED_ON jumper. It is important to be

aware that timekeeping can be subject to a degree of

inaccuracy, particularly when working in the minute

range.

blinking. Changes are made in the same way as

when setting the switch OFF time using the S1 and S2

buttons. Once the correct value has been set, press

and hold S2 again to complete the programming

process - the parameters will be stored in non-volatile

memory.

Fig. 2 Mounting diagram

Resistors:

R5-R12: ....................................................................120 Ω

Capacitors:

R1-R4:.......................................................................10 kΩ

C3-C5: .....................................................................100 nF

C1, C2:.....................................................................100 μF

Semiconductors:

D1:..........................................................................1N4148

T1, T2: ......................................................................BC557

U2:...................................................................ATtiny261A

Other:

ZAS, NC, NO: ............................ARK2/500 connector

LED_ON: ..................................goldpin 1×2 + jumper

T4:........................................................DO NOT MOUNT

LED1: ...................................................dual LED display

S1, S2: ...........................................................microswitch

PK1:....................................................................RM84P12

U1: ..............................................................................7805

T3: .............................................................................BC547

SEK/MIN:.................................goldpin 1×3 + jumper

List of elements

Button for setting the relay OFF time

Button for setting the relay ON time

Empty, unused solder fields

Display deactivation jumper

Selection of minutes or seconds mode

NC NO

AVT SPV reserves the right to make changes without prior notice.Installation and connection of the appliance not in accordance with the instructions, unauthorised modification of

components and any structural alterations may cause damage to the appliance and endanger persons using it. In such a case, the manufacturer and its authorised representatives shall

not be liable for any damage arising directly or indirectly from the use or malfunction of the product.

The self-assembly 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 regulations

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

https://sklep.avt.pl/

AVT SPV Sp. z o.o.