IMPROVE THE ALARM

As a result of system analysis the author came to the conclusion that there are two apparent downsides:

 

1. Battery power to the bidirectional remote control rather quickly (in six months) goes down.

 

2. The sound volume of the alarm in the key FOB bi-directional remote control is too small — it can be heard only within the room, and then — in relative silence.

 

How to eliminate these shortcomings? Do the power supply stabilizer.

 

The easiest way to improve alarm systems is that bidirectional remote-pager is at home and connected (to save battery) to continuously power supply with good filtering of the output voltage stabilization in the power supply. This will require a power supply with “non — standard” voltage 3- 4 V, which can be made independently at any convenient scheme (in the literature described a variety, for example, chip-stabilizer LM7803SR). If such chips are available from electronic hobby no, I recommend to use a simple voltage stabiliser circuit is shown in figure 1. In experiments with the device, conducted by the author, it was found that bi-directional remote-pager is not afraid of increasing the voltage to 4.2 V (current consumption in this case with the active sound and light indication 10 mA). All elements of the remote work fine around the clock without interruption. Increase heat SMD elements that comprise the remote is not detected.

 

Fig. 1. A schematic circuit diagram of a simple voltage stabilizer.

 

This device works well in the author’s version and provides an output voltage of 3.3 V with a current of 10 mA. Due to the small power range bidirectional radio transmission may be shortened, but still it becomes less than 100 m, which is quite acceptable for control of the car in front of the Windows of his house

 

As the network rectifier is applied to battery charger for Nokia cell phone-640, which is considered today an anachronism. The radio Amateur in the vaults might be “unused” power supplies or battery chargers for cell phones. Will suit those that have output voltage 3.6 — 4.2 V (it is marked on the case wall charger) Diodes VD1, VD2 can be applied from КД105, Д220, KD213, 1N5401, 1N5407. On each of the two diode voltage drop in this circuit will be 0.6 V, the Zener diode VD3 (КС133А) can be replaced by two Zener diodes connected in series type КС107А or similar, calculated on the total voltage up to 4 V. Apply here for a popular Zener type КС139А undesirable, as the voltage stabilization has a relatively large scatter (up to 4.2 V) Oxide capacitor C1 is better to use overseas, for example, firms Hitano or similar — with small dimensions and relevant (as detailed on the wiring diagram) parameters. The R1 resistor — MLT type. It limits the current. Its resistance is in the range of 13 — 27 Ohms, the power dissipation is 1 watt. The elements of the stabilizer are “hiding” in the same housing of the key FOB in the space for installing the AAA batteries.

 

After the recommended supplements, bi-directional key FOB-pager will serve around the clock for several years, and the change of batteries it is possible not to worry.

 

The proposed stabilizer with an output current of 10 mA is suitable for powering a bi-directional remote reporting alarm and other consumers that require such low current, for example, some models of portable clocks-alarms on LCD. This scheme can be take note and use universal.

 

As noted above, for keychain-pager you can use another power source, and the higher his current output, the louder the beep.

 

The sound output from the built-in primer in the trinket-pager only enough to be able to hear in your pocket or in a small room (10-12 m²) in relative silence. Of course, this option requires an increase. One of the ways (to slightly raise the voltage of the power supply chain) we used above. Another step to increase the sound volume (without changing the design and scheme of the keychain on SMD components) is to install a more powerful sound emitter.

 

Photo 2. PCB bi-directional remote:

a — Board radio transmitting device 6 — Board processing and encoding of signals.

 

Photo 2 shows the two printed circuit boards located on the SMD elements of the bidirectional remote control. Left — to-Board transmitting devices (shown by the spiral antenna). It is inserted by means of two pad connectors to the main Board with processing and encoding of signals (to the right in photo 2). This Board is also visible to the right sound emitter of the type OVO-101R. The sequence of the tone it produces electronic circuit device. The sound emitter is a dynamic capsule with a coil resistance of only 5.6 Ohms. Master transistor, is included as a current amplifier (also in SMD version), has a reserve of power to enable instead of the regular more powerful sound emitter, which is similar in electrical characteristics of dynamic head YD40-1 (coil resistance of 8 Ohms, the power is 0.25 W). This dynamic head is used in some models of cordless phones, for example, Sanyo CLК-8580. Instead, you can use another dynamic capsule, or even a phone.

 

Now, despite the relatively “weak” current power source, the sound volume has increased several times and the alarm is clearly audible within a two bedroom apartment. Dynamic head is mounted on a flexible mounting cord, for example MGTF-0,6, outside the body of the keychain, placed in a separate tiny box Because the bidirectional remote pager, tied now to the mains 220 V, lost mobility, is a miniature dynamic speaker mounted in a small box outside the console, do not spoil the device and adds to his effectiveness.

 

Photo 3 shows points on the PCB to connect additional speaker.

 

Photo 3. The point of connection of additional sound emitter.

 

Several of the worst results of increasing the sound volume (relative to the dynamic head YD40-1) is obtained by parallel connection of regular primer and sound dynamic capsule from the old wrist electronic clock (with red led indicators and two batteries type SC-21, connected in series) manufactured by electronics the Resistance of its coil is 23 Ohms. The volume alarm FOB in this case increases approximately two times. Such a capsule (diameter 6.5 mm, height 2.5 mm) can be easily installed in the housing of the key FOB. But all he is now is because they are long out of production.

 

If an audio emitter to apply a dynamic capsule with a larger (than the YD40-1) resistance of the coil, for example, more than 20 Ohm (DAMS-4M, TEMP-3, or equivalent), staff from the scheme is not to exclude.

 

The device is now ready for operation. But there are some features of practical implementation, which should be strictly observed. As noted above, the function of the pager will only work when the system is armed using a bi-directional remote control or when Avtopostavka. That is another case of great in the device.

 

You come to the house and put the car on protection using one-way remote (the second remote alarm that is always with you). Back upstairs, push a button disarm permanently connected to a 220V two-way remote-pager. However, the led on the remote-pager will blink twice and twice with a pause of half a second you will hear a short beep in confirmation of executed command. As the door of the car one time opened, the alarm system automatically turns on protection mode, than in a two-way remote-pager will flash the led once and you will hear a short beep. Thus, the control conditions with two-way remote-pager are completed and now in the case of unauthorized opening of car doors remote-pager will notify its owner with loud alarm “Alarm!”.

 

Alarm Mongoose Duplex 3D model has a lot of service functions, such as “quiet guard”, “car search”, “delayed protection” mode “Valet” program key fobs and many others. They will all be available with a bi-directional remote control (pager). How to enable them and what they mean — is described in the manual of this system. Now (after the recommended innovations) in the system involved two remote control, one of them (alarm and beeper) works stationary, so the alarm began to function (be used) most fully.

 

In the author’s version considered security system of the vehicle is implemented and successfully operates today on the car “the Sable” (battery voltage 12V).

 

To make such a revision virtually every radio Amateur. The prospect of applying the proposed recommendations, in my opinion, is huge. You should only assume that in the near future in connection with the progress of electronic technologies will be created and will go on sale new models of alarm systems for various purposes (including with pager system). And what to do with old, but well working system? You can, of course, to sell the car with them, and can this alarm be removed and adapted for any purpose, until the remote protection remote building basement, cellar in the countryside or gate. But you never know what will fit system for radio Amateur use in everyday life the sensible approach of a prudent owner and harnessing creative flair. The use of such alarms with a remote alert mode (avtopeydzher) in the domestic environment of each home is limitless.

 

A. KASHKAROV, St. Petersburg