Category Archives: GSM Gate Opener

GSM Dialer/Gate Opener Current Consumption Question

Hi there,
How many milliamps does it need from the alarm board to run?

(no name supplied)

GSM Dialer Current at various voltages

GSM Dialer Current Graph

As can be seen from the graph the current consumption drops with increasing supply voltage.  The is due to the use of an efficient Switch Mode Power Supply (SMPS) buck regulator on board which converts a high voltage at low current to the low voltage and high current required by the GSM transmitter chipset.  The GSM system requires up to 2 Amps at 3.6v.  However, due to the SMPS at 28v the current requirements during transmission are as low as 60mA average.  This can also be explained due to the 12.5% duty cycle used during GSM TDMA transmissions.  GSM transmits only in short powerful bursts with a 1/8th duty cycle.

The system’s electrical energy requirement every second (by definition this is know as Power) is the same whether the PCB is supplied by 12v, 18v or 28v.  Power consumption can be calculated for DC loads using the following formula:

Power  = Voltage x Current  normally written  P = VI

The inverse current plot is expected when we re-arrange the formula as follows:

I = P/V

As the power requirement, P, is constant no matter what voltage we supply we see as the voltage, V, is increased I, the current, must be reduced.

GSM Dialer power requirement

GSM Dialer Power Consumption

The above graph showing power consumption at various voltages shows the most efficient supply voltage is approximately 12v particularly when idling.

Please note these figures were obtained on the 1800MHz band (EE network) with a low RSSI of 10.  They were obtained during the higher power ringing phase and would drop during talk-time.  Transmission at 900MHz (O2 network) may give higher current consumption due to the higher power output of the transmitter but may also be lower if the signal strength is superior.
Here is the measured current consumption at various DC voltages:

20mA idle
60mA during call (peak 70mA with relay on)
26mA idle
95mA call (115ma Relay)
30mA Idle
110mA (145mA Relay)
127mA (160mA Relay)



The GSM Alarm Dialer and SMS sender is available from the Advent Controls website using the following link:


Do we want nano SIMs?


Initial Design Layout for B3.01

We’re currently re-designing the twin output relay board which up to now has had no input.  It’s also a pretty old design (>2 years which is amazingly geriatric in the GSM industry) so is well in need of updating.  It’s tempting to go quite radical as we could add Bluetooth quite easily for number setup but that may have to wait.

What we would love to know is whether you as an installer want to see a nano SIM holder yet.  The larger micro SIM is becoming less common and I frequently find callers to the office have no means of fitting the dialer/gate opener SIM in their own mobile for registering/testing.  Do you want to see our products with a nano SIM holder?

GSM Gate Opener A3.02

Advent Controls A3.02

It is likely, as these boards have some crossover in terms of application, we will put the nano SIM on this board and the full size SIM on the 1-out 2-in board and see which users prefer.

Please leave your thoughts in the comments they would be very much appreciated! (click leave a reply at the top)

GSM Roller Shutter Controller Link

GSM Gate Opener Link

Disallowing some users access to the relay on the GSM Dialer and Gate Opener

We had a user question which required a unusual solution so I thought this is ideal for the blog.  Quite crafty I’d say!


Another question for you. The relay can be activated with a call. Is there any way of setting the numbers that can do this. I don’t want all the text numbers to be able to use the relay. See I have set this up as a back up to a pager system. Should it fail I only want 3 numbers only to be able to set it off the relay. Thanks again for your time and help

GSM Switch

GSM Switch with Volt-Free Relay Output


I had to have a little think about this one. The easy answer is no. All numbers can operate the relay. What you can do though it add an extra digit to the end of the phone number you don’t want allowed. When the dialer searches the memory it looks at the last 8 digits of the number you gave it. If I did this with my number:

Actual: 07574163367

Given to dialer: 075741633670 (added a 0)

The dialer would get 07574163367 from the network but when it looks in its memory it will only see 41633670 which will not be a match so it will not allow the relay to be operated. However, when it sends messages or dials the number you have given it, it will add the extra 0 but the network will know this is too long and ignore it. Try the SIM in your mobile and see if it does actually call/send messages with the extra character. Mine does and I use an EE SIM.

So for those you want to access the relay put the number in correctly and for those you don’t add the character.


Advent Controls

GSM Dialer Link

GSM Gate Opener Link

GSM Dialer Connection to a PIR Detector and use as a GSM Gate Opener

Hi, can I check how I would wire up a standalone PIR to this to activate the dialler (seperate to the alarm panel)? Also out of curiosity the output controls on this autodialer are they the same as the GSM gate opener board (ie so can be used to open gates too)? Many thanks.

GSM Dialer

Advent Controls GSM Dialer and Gate Opener


You can wire the PIR output directly to the GND and input terminal (A or B).  The dialer expects and Normally Open (NO) type of signal so it send messages when the equipment closes it’s output contacts.  With a PIR, however, the output is Normally Closed (NC).  So you just need to tell the dialer to trigger when the input goes open as follows:

inlevel open

The gate opener and dialer are the same product except people use the inputs on the dialer and outputs on the gate opener.  It is perfectly OK to use both the inputs and outputs at the same time and hence use the same board as a dialer and a gate opener.


Advent Controls

GSM Dialer Link

GSM Gate Opener Link

What’s new in October

This month we sold out of the GSM autodialer  ( and gate opener boards again.  We made a much bigger batch last time but unfortunately due to some large orders in September this did not cover demand.  We have scheduled another batch to be produced in Decemeber, earlier than planned, so this should not happen again.

GSM Switch

GSM Switch with Volt-Free Relay Output

The lack of the auto dialer has provided us with the opportunity to catch up on a few things from redesigning the office to finishing off some new products.  One product of great interest that I have been working is our latest GSM intercom.  It’s been mentioned before on the blog but this week I have been working on the prototype and have something physical to work with.


GSM GOLD Intercom Development Unit

The finished product should look great as the prototype is very appealing despite it not being assembled correctly by us!  We will be leaving the plastic assembly to the professionals in production.


GSM GOLD Intercom Development Unit showing thickness

The concept was to create a flat GSM intercom which appears flush mounted despite being surface mounted.  It was to feature an internal aerial making installation quick and simple.  The challenge of packaging the electronics found on our existing intercom design (shown below) ( into a 5mm thick PCB was tough but we did it.  I suspect future designs will be even thinner although the limiting factor is the speaker at 5.5mm thick.  With 1mm plastic either side for protection this gives a minimum thickness of 7.5-8mm including the rear seal.

GSM Intercom PCB

1 button GSM intercom PCB

GSM Dialer and Gate Opener Out of Stock

Unfortunately due to high demand recently we have again sold out of the A3.02 dialer and relay board.  Although we expected the latest batch to have been assembled by now we also ran into a supply chain issue with a component we only use on this product (the AP5004SG-13 buck regulator if you’re interested!).  The stock we thought was there in our distributor’s warehouse wasn’t.

GSM Switch

GSM Switch with Volt-Free Relay Output

We’ve managed to secure a supply of the chips due to land on Friday 10th of October and our assembler is able to build the PCBs as soon as they arrive so we should have a good supply of the board at some point mid-week next week.  Currently we expect this to be Wednesday 15th of October and expect them to still be warm having just come out of the reflow oven!

Sorry for any inconvenience this has caused.  Hopefully the period of no stock will be as short as possible.

Michael Beaver


Advent Controls

1 Button GSM Door Entry Intercom Video

In the video Michael demonstrates our classic 1 button GSM Door Entry Intercom.  It’s been around a while now and has been refined into a very solid system with excellent audio and an easy to use programming method.

The Advent Controls GSM Door Entry Intercom System Key Features:

  • Internal Aerial for Simple and Fast Installation
  • Simple SMS Programming using Intuitive Commands
  • High Audio Quality
  • Space for up to 384 Numbers
  • Dial-to-Open Access Control
  • Lowest Price GSM Intercom on Market

The system uses a high production volume enclosure with our custom UK designed and built electronics inside.  The design of the enclosure is excellent giving good audio and protection against the elements.  As with all of our products the firmware is written in house and has been refined over time to work seamlessly with every network.

The Intercom is available on our website here for just £149 (£124.17+VAT!)

GSM Intercom

Mobile phone based Door Entry System