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Small-sized sound beacon for model of rocket
Purpose and the description of work
The sound beacon is intended for simplification of search of model of a rocket after a landing. However, it is possible to use a sound beacon and during start-up, rise and descent of model of a rocket. It will simplify a problem of tracking of model of a rocket at a stage of flight.
By development of a beacon it was necessary to solve some problems. The beacon should be small in the sizes, have small weight, to be lowpower, to have the small price, to be easily repeated for nonspecialists in electronics, to have simple management, to be reliable, to have an opportunity to change and improvement during an operating time of experience at its operation.
As a result, to solve all these problems I has decided to make a sound beacon on the basis of the elementary microcontroller ATtiny15L of firm Atmel. Why this microcontroller? In the first, microcontrollers of firm Atmel are widespread enough and inexpensive. In the second, this microcontroller has a small amount of pins. In the third, this microcontroller has execution in case DIP (usual pins) that will allow to solder or program without effort it to the nonspecialist. In the fourth, the given microcontroller has a built in generator of clock frequency that simplifies, reduces the price and reduces the scheme. In the fifth, the given microcontroller has an opportunity to include the internal scheme of reset and suppy supervisor, that also simplifies and facilitates the scheme.
A feed is the most convenient to carry out from tiny cylindrical batteries of 9 V or 12 V. Possible to find batteries which have the small sizes and small weight. How to make reliable connection between contacts of the battery and the scheme of a sound beacon will have to solve independently. For example, it is possible to buy the ready container for the battery, it is possible accurately not overheating to solder the battery to its contacts of a wire, or easier to attach wires by means of any glue. Personally I solder wires and then I wind places of soldering with a string filled in by glue. It looks, can and it is not so beautiful, but has the minimal weight, and it is very important for model of a rocket.
So, power is on. The sound beacon as follows works. After switch on of power the beacon expects pressing the button of delay set. Now it is necessary to establish time in minutes prior to the beginning of submission by a beacon of periodic sound signals. For this purpose it is necessary to press and keep the button. Addition general time of a delay every minute will be signalled by means of a blinking of a light-emitting diode. The light-emitting diode blinks with periodicity about one second. For example, for set a delay to three minutes it is necessary to press and keep after power on of a beacon the button within approximately three seconds, thus the light-emitting diode should blink three times. During or at once after the third blinking of a light-emitting diode the button should be released. In three minutes the beacon will start to submit periodic sound signals and will so work before power switching-off, or until while the battery will not be unloaded. If, for example, time of a delay has been exposed incorrectly it is possible to act in two ways, in dependence that aside reduction or aside increases it is necessary to change a current delay. If the delay should be reduced, it is necessary to switch off and again to power on and to lead process of delay set anew. If to a current delay it is necessary to add simply even minutes a power can be not disconnected, and simply to press and keep the button still time so much how many it is necessary. The light-emitting diode will blink and show again added minutes, but the moment of the beginning of readout of minutes remains former - from the moment of the first delay set.
The basic electric scheme
Bill Of Materials
BZ1 - ÍÐÌ14À
C1 - 0805 0,1 mkF
C2 - D-type 220 mkF
DA1 - TDA3664
DD1 - ATtiny15L
R1-R3 - 0805 100 Îì
SB1 - TS-A6PG-90
VD1 - 0805 KA-3020SGC
VT1 - BC817-40 (analog 2SC2712)
Some explanatories concerning a choice of radioelements. Buzzer it is chosen for a reason of the minimal size and a minimum of additional elements, therefore such, that has the built in generator of sound frequency. Condenser C2 should be enough the big capacity that at short-term loss of contact to the battery of a feed that, for example, can happen because of unreliability of the contact or at a tinkling sound of contacts at impact of the landed model of a rocket about the ground, the microcontroller was not dumped. If the microcontroller will be dumped, it will appear in an initial operating mode, that is will expect delay set and any sound signals will not give out. Resistors have a standard size 0805, but can be basically any. Resistors with smaller standard sizes are more complex for soldering for nonspecialists but if to you it will not be complex can apply them.
File with the program for the microcontroller:Majak.hex
Sets of "Fuse" bits:
CKSEL0 = 1 (not programmed)
CKSEL1 = 1 (not programmed)
RSTDISBL = 0 (programmed)
SPIEN = 0 (programmed)
BODEN = 0 (programmed)
BODLEVEL = 0 (programmed)
To program it is necessary in the parallel way as it is necessary to disconnect function of Reset at a corresponding pin of the microcontroller, differently - at consecutive programming you at switching-off of function of Reset cannot reprogram the microcontroller any more if it is required to you in the future or if you simply were mistaken at programming. If you decide to program in the consecutive way it will be necessary in first to not program bits RSTDISBL and SPIEN, and in second to add in the scheme a chain of Reset on RESET pin of the microcontroller, for example, in the elementary variant it can be the pull-up resistor on 10 kOm to a 5 V and the condenser 0,1 mkF on the GND, but, by my experience, this scheme not always reliably works and it is better to apply a special chip, for example ADM803.
For greater objectivity it is necessary to tell, that the given microcontroller has one lack which is complex for bypassing to the nonspecialist. There is such concept - calibrating byte. Its value should be equal to the number which has been written down in special area of memory inaccessible from program. This number is defined for each microcontroller by its manufacture and it is necessary for exact fine tuning the built in clock generator on frequency of 1,6 MHz. In the applied program I have left that calinrating number which has been written down in my microcontroller, it is equal 6Eh. Basically, if frequency of the built in clock generator will differ from nominal it is not too terrible. It will be simple each minute to be counted little bit more quickly or more slowly, and it is not too important in most cases applications of a sound beacon.
For experts I write where it is possible "to tighten up" calibrating value in a file of the program. Consider it you can by means of programmator. Then in a file of the program find following string:
:1000100000C01895F8940EE601BF0E001BD9C
Symbols designated by red color, is the calibrating value which has been written upside-down (rear order). After change of value if only you did not change it in a window of the program for work with programmator, and changed in the file do not forget to count the control sum of a line which is equal an initial variant 9Ch and is in its end. How to calculate the control sum here I shall not tell, experts so know.
The timer with a sound beacon
I had been developed the elementary scheme on the PIC microcontroller which carries out functions of the timer of system of rescue and the electric impulse with the set delay on an electroigniter a charge allows to submit. The second function of the given scheme is submission of operating impulses on the device of the sound notification (buzzer) with the built in generator. Algorithm of work of the scheme following. After short circuit of a circuit of a feed the microcontroller begins periodically to switch buzzer with the built in generator.
Consumption of a buzzer is insignificant, therefore it quite becomes impregnated with port. At the given program after 10-th sound signal (on time about 5 seconds at the given frequency of the quartz generator) the command on start of an igniter duration nearby 0,5 ñåê stands out. After that the scheme continues to give out sound signals that allows to find out easier a rocket during and after descent.
Here the scheme of the timer, hex-file and text of program:Timer.zip 26,9 Kb
The equipment for measurement of acceleration
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