Quasar 3140 User Manual

QUASAR CODES 3140 - DTMF Telephone Relay Switcher

General Guidelines for Electronic Kits and Assembled Modules

Thank you for choosing one of our products. Please take some time to carefully read the important
information below concerning use of this product. The assembly and operating instructions are on the
following pages.

WEEE Directive (Waste Electrical and Electronic Equipment)
Notice To All European Union Citizens. Important environmental information
about this product.

The crossed out wheeled bin symbol on this product, package or documentation
indicates that disposal of this product after its lifecycle could harm the environment.
Do not dispose of this product (or batteries if used) as unsorted municipal waste. It
should be disposed by a specialized company for recycling.
The unit should be returned to your distributor or to a local recycling service. Please

respect the local environmental rules. If in doubt contact your local authorities about waste disposal rules.

Safety: General rules concerning safe use of our Kits or Modules.
To ensure your safety, please observe these safety measures. In no way are these complete. As
safety requirements vary, please check with your local authorities, in order to comply with local
requirements. If in doubt, seek the help of a qualified person.

Battery or wall-adaptor operated devices are safe devices. They do not require special attention
unless mains voltage is connected to an output e.g. a relay.

To ensure electrical safety, and also protection from fire or personal injury, make sure your
mains operated equipment complies with these safety hints:

• Use a suitable plastic enclosure. If a metal enclosure is used, make sure it is properly earthed.

• Use a power switch if the device consumes more than 10W. Use a double pole switch for mains

operated, transformer-less kits.

• Mount a fuse in series with the mains switch. Use a slow blow (T) 50mA fuse for transformers up

to 10W and a 100mA fuse for transformers up to 20W.

• Use a mains input connector, or a robust power cord with a clamp.

• Internal wiring carrying mains voltages must have a minimum cross-sectional area of 0.5mm

2

.

If supplied, attach the power rating label near the power cord of the device and fill-out the mains voltage,
frequency, power consumption and fuse values.

Troubleshooting and Support

90% of non working kits are due to poor soldering.
We operate a Get-You-Going service for non-working kits but there is a charge based on the time and
components needed to complete the repair. Quite often it is not economically viable for us to repair and it
is cheaper to supply a new ready made product at full cost.

Disclaimer

Quasar Electronics reserves the right to change product specifications or to discontinue products without
notice. Quasar Electronics cannot be held responsible for any loss or damage, direct or indirect, which
might occur from the use of a product. Quasar Electronics Kits or Modules 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 are not suitable for use as or as a part of life support systems, or systems that might
create a hazardous situation of any kind.

QUASAR CODES 3140 - DTMF Telephone Relay Switcher

This device connects to the telephone line and can be
used to remotely control up to 4 relay outputs using a
DTMF (tone dialing) telephone. A number of user
settings are available to improve the useability and
security of the device. The unit comes complete with
a small plastic case with silk-screened front and rear
panels. NB This unit is not PABX compatible!

The unit is controlled by an Atmel 89C2051
microcontroller. Source code is not available.

** WARNING! The maximum connection voltage is

48Vac unless the screw terminal block connectors are
insulated to prevent exposure to hazardous voltages.

FEATURES
Ouputs Relays x 4

Output rating 5 Amps @ 240Vac** / 24Vdc max.

Operating voltage 12-15Vdc centre positive (regulated)
Operating current 30mA with no relays operated

120mA with all relays operated

Connections 1. 2.5mm DC power jack

2. RJ-11 for telephone line

3. 4 x 3-way pluggable screw
terminals for relay contacts

Case size 13cm (W) x 10cm (D) x 3cm (H)

(6.1” x 4” x 1.3”)
User Settings
(see text)

CIRCUIT DESCRIPTION
We will not review the operation of how telephone
lines work or the detailed operation of the various ICs
used. See the ‘References’ section for Web links where
you can get this information.

The brains of the switcher is the Atmel AT89C2051
microcontroller, IC4. Incoming ring is detected via C4,
R7 and the opto-coupler IC2 and connected to pin 6 of
the microcontroller. This pin also has the ‘Password
Reset’ switch connected to it (more on this later).

The incoming call is answered by connecting the
circuit based around Q1 and Q2 (an electronic holding
coil) to the line via IC1, a bi-directional opto-isolator.
This circuit has a low DC resistance but a high AC
impedance which is required by telephone circuits
when the line is looped. The RC network consisting of
R4, R5 and C3 is used to provide impedance matching
to the telephone line. The metal oxide varistor
protects the switcher from telephone line transients.
The configuration and values used here are optimised

for use with most phone systems thoughout the world
without any need for customisation. They can be
changed by the end-user to meet specific needs if desired
e.g. to meet local approval standards.

DTMF detection and decoding is provided by IC3.
This chip, an 8870, is a complete DTMF receiver

1. Password

2. Tamper

3. Rings to answer

4. Auto hangup time

5. Lockout

which is able to detect and decode all 16 DTMF tone
pairs into a 4-bit code. When a valid DTMF digit is
detected the 4-bit code is placed on pins 11-14 and a
‘data avaliable’ output, pin 15, is set to a logic high.

The output relays, RL1-4, are controlled via the relay
driver IC6. One output from the relay driver (pin 14) is
used to output a 800Hz software generated tone into the
telephone line via the impedance matching network. This
tone is used to signal the user when commands have
been completed or of any command errors.

User settings are stored in IC5, a 24C01 EEPROM. The
microcontroller ‘talks’ to this device using a 2-wire I2C
bus via pins 18 and 19.

IC7 provides two functions – a regulated 5V power
supply output and detecting when the phone line is
‘looped’ (in use). This chip is a Maxim MAX666 low
power programmable voltage regulator with on-chip
low-battery detection, mainly intended for use in battery
powered equipment. The regulator output voltage is set
via the ‘VSET’ input (pin 6). By tying this pin to ground
the output is fixed at 5 volts. We have used the low­battery input to monitor the state of the phone line.

An idle (not in use) phone line normally has about
50VDC across its pair of wires. This voltage drops to
less than 20V when the line is in use. The MAX666 Low
Battery Input (LBI, pin 3) is one side of a simple voltage
comparator which compares this input to an internal

1.30V reference voltage. When the voltage at the LBI
input falls below the reference voltage then the Low
Battery Output (LBO, pin 7) will go LOW.

The phone line is connected to the comparator input via
the diode bridge B2 and resistors R15 and R16. The
diode bridge makes sure that the voltage polarity
connected to LBI is the same regardless of which way
around the phone wires are connected. The resistors form
a voltage divider which is used to set the ‘low battery’
threshold at LBI. For the values used the LBO output
will go LOW when the phone line voltage drops below 25
volts, indicating that the line is in use (looped).

PCB ASSEMBLY (AS3140 users can skip to page 2)

First check the components supplied in the kit against the
component listing. Identify all the components. It is
generally best to solder the lowest height components
first: the resistors, diodes & IC sockets. Leave the
connectors and relays until last.

Note that two components, resistor R14 and capacitor
C11, are mounted inside the IC sockets for IC3 and IC4
respectively. This is no problem – just fit these
components before the IC sockets.

Make sure to get the diodes and electrolytic capacitors
the correct way around. Match up the bar on the diodes
with the bar on the overlay. The negative lead of
electrolytic capacitors is marked by a ‘stripe’ whereas
the PCB overlay indicates the hole for the positive lead.

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QUASAR CODES 3140 - DTMF Telephone Relay Switcher

When fitting the MJE340 transistor, Q1, check the
PCB overlay first. The thick ‘line’ on the PCB
indicates the back of the transistor which may have a
metal surface. If not then use the markings on the
transistor – they indicate the front of the transistor.

Make sure the power jack is facing straight out, not
skew. We have made the front panel hole 0.320” which
will tolerate some shewness.

When mounting the connectors make sure they are
sitting right down on the PCB before soldering.

Do not insert any ICs yet!

We are now going to fit the assembled PCB into the
plastic case. Before that check all your work carefully.
Look for unsoldered joints and any solder bridges or
splashes that may be shorting out adjacent pins.

Now comes assembly of the front panel. Start by
inserting the LED clip into the hole, pushing it in from
the front. Now insert the LED into the clip from the
rear. The LED should “click” into place.

Turn the LED in the clip so that the long lead is to the
right (as viewed from the front). This is very
important so make sure it is right. Now bend the
leads down at right angles, about 3mm from the LED
body, as shown below. Use a pair of long nose pliers to
hold the leads while bending. Cut the leads off to a
length of about 9mm from the bend.

Fit the front and rear panels to the PCB. Be sure that
the LED leads are inserted into their matching holes on
the PCB. While holding the panels in place slowly
position the PCB into the base of the plastic case,
making sure that the front and rear panels slide into the
slots provided. Secure the PCB to the case using the
self-tapping screws then solder the LED leads from
the top of the PCB.

Do not fit the plastic case lid just yet. Proceed to the
next section ‘PRE-TESTING’. Now fit the plastic case
lid and secure it in place.

For 2 photos of the completed kit see

http://www.quasarelectronics.com/jpg/3140_1.jpg

http://www.quasarelectronics..com/jpg/3140_2.jpg

PRE-TESTING
Insert IC7 (MAX666) and connect a 12-15Vdc power
supply to the DC input jack. Use a multimeter to check
the 5V supply. Easiest place to measure this is across
pins 20 (+) and 10 (-) of the IC4 socket. If all is well
then remove power and insert the rest of the ICs into
their sockets. Check that the IC legs are actually inserted
into the socket and not accidently bent up underneath
the IC body (quite a common fault).

USING THE UNIT FOR THE FIRST TIME

Before you can use the unit for the first time the various
user settings must be set to their ‘default’ values. To do
this,

press AND hold the 'Password Reset' button

while powering up the kit. Hold the button down for
a further 2 seconds before releasing it. This procedure

is also used you user forget the password.

The default value for each setting is:

Password ................. 0000

Tamper .................... 3

Rings to answer ....... 3

Auto hangup ............ 30 seconds

Lockout ................... Disabled

Each of these settings can be changed by the user to suit.

CONNJECTION AND OPERATION

Protect unit from power surge & lightening strike damage.

Connect the unit to the phone line using a suitable cable (and
filter if the line has broadband). Only the two inner pins of the
RJ-11 plug are used. Some cables do not – check before using!
Connect a 12-15Vdc centre positive REGULATED power supply.
On first use please follow the procedure described previously to
set the user settings to their default values. The unit is now ready
for incoming calls.

Dial the phone number to which the kit is connected.
After 3 rings it will answer with 4 short beeps. Type in
the password (0000) followed by the '#' key. If the
password is correct the kit will respond with 4 short
beeps. It is now waiting for a command.

COMMANDS
A command is a string of characters starting with *
or # and ending with a #.

Entering a * at any time after the first character aborts
and starts again.

1. *<1-4># - operate one of the four relays 1,2 3 or 4.

2. #<1-4># - release one of the four relays 1,2,3 or 4.

3. *5# - set password

4. *6# - set tamper setting

5. *7# - set number of rings to answer

6. *8# - set auto hangup time

7.

8. *0# - forced disconnect

9. #0# - release ALL relays

- set lockout time

*9#

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