AVT 1995 Manuale utente
1
Timer designed for precise countdown of preset time
intervals in the range of 1 second...99 minutes. It
enables entering the countdown time in minutes and
seconds. Its resolution in the range from 1 second to
9 minutes and 59 seconds is 1 second, while in the
range of 10.99 minutes it increases to 10 seconds. The
integrated relay and easy, intuitive operation qualify
the unit for the implementation of timing functions in
uncomplicated automation systems.
• executive circuit - relay 230 VAC / 8 A
• supply: 8...12 VDC / 80 mA
Specifications
• relay connector NO or NC (normally open or
• settings memory
• maximum timer range - 99 minutes
normally closed)
• board sizes: 58×48 mm and 53×27 mm
Figure 1 shows schematic diagram of the timer. The
device is designed to be supplied with 8-12VDC.
Rectifier diode D1 protects the circuit from incorrect
polarity. Supply voltage is stabilised by U1, while
capacitors C1... C4 ensure that it is adequately filtered.
The operation of the timer is controlled by an
ATtiny26 microcontroller timed by an internal clock
signal. Its operating status is reflected on a triple
seven-segment display with a common anode.
Cathodes of the 3-digit multiplexed LED display are
connected via current-limiting resistors R5.R12 to the
PA0-PA7 ports of the microcontroller. Function of the
keys that switch on the power supply to the displays
is performed by transistors T1-T3 controlled from
ports PB2-PB4. For settings and timer control, the unit
is equipped with 3 buttons marked S1, S2 and S3.
Signals from the buttons are routed to ports PB0 and
PB1 and PB6, the active level is logical '0'. A relay of
type RM84P12 (coil 12 VDC, contacts 8 A/230 VAC) is
used as the executive circuit. To extend the timer's
functionality, the NC and NO contacts are provided
for the relay.
Circuit description
Precise Timer 1 second...99 minutes
AVT 1995
ASSEMBLY DIFFICULTY
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Figure 1. Schematic diagram
Fig. 2. Components arrangement on PCB
2
If the circuit is mounted without any errors, using a
preprogrammed microcontroller and with efficient
components, it will work as soon as it is energized.
When controlling a load of significant power,
attention must be paid to the load on the relay
contacts and PCB tracks. To improve their load
capacity, the exposed tracks can be additionally
tinned or, even better, a copper wire can be laid over
them and soldered.
Mounting of the circuit is typical and should not
cause any problems; it follows a standard procedure,
starting with the smallest components and ending
with the largest. Once the two boards have been
mounted, connect them together using an angled
goldpin strip.
The timer must be mounted on two PCBs, the design
of which is shown in Figure 2.
Mounting and start-up
3
A blinking dot next to the unit digit indicates that the
timer is running.
Operation of the timer is simple and intuitive. The S1
and S2 buttons are used to increase and decrease
values, while the S3 button is used to start
countdown. Each time S2 is pressed, the value will
increase and each time S1 is pressed, the value will
decrease. To change the value faster without having
to press the button repeatedly, press and hold the
respective button. On the three-digit display, in the
range of 1 second from 9 minutes and 59 seconds,
the setting resolution is 1 second, while above this
range it increases to 10 seconds. The set value is
remembered in non-volatile memory, so you do not
need to re-enter it when the device is restarted.
Once the countdown has started, you can stop the
timer at any time by pressing the S3 button. In this
mode, the digits on the display will start blinking.
Pressing the S3 button again briefly resumes the
countdown, while holding the S3 button longer
returns the device to its initial value. When using the
timer, you should be aware that the timer may be
subject to a certain degree of inaccuracy, particularly
in the minutes range.
Operation
C1
C2
U2
1
U1
T1
T2
T3
T4
A
C
D1
D2
R6-R13:...................100 Ω (brown-black-brown-gold)
Capacitors:
C1, C2:.....................100 μF !
Semiconductors:
Resistors:
R1-R5: .....................10 kΩ (brown-black-orange-gold)
C3-C5: .....................100 μF (can be labelled 104)
D1, D2:....................1N4007 !
SV1:..........................goldpin 1×16pin
U1:............................78L05 !
Other:
S1-S3:......................microswitch button
U2:............................ATtiny261 + base
T4: ............................BC547 (BC548) !
LED1: .......................display AD5636
ZAS, NO, NC: ........screw terminals
PK1:..........................relay RM84P12 (or similar)
T1-T3:......................BC557 (BC558) !
List of elements
Begin assembly by soldering the components onto the board in order of size from smallest to largest.
When mounting components marked with an exclamation mark, pay attention to their polarity.
Access the high-resolution images using links and download the PDF.
Frames with diagrams of the leads and symbols of these components on the PCB and photographs of the
assembled kit may be helpful.
!
Pobierz PDF
4
1 sek - 99 min
1 sek - 99 min
Figure 3. Relay switched on during countdown
Figure 4. Relay switched off during countdown
START
START
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
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.
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.
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