The electronic assembly is a mini transmitter audio / video VHF, can be activated and deactivated by a coded radio on 433 MHz. It is suitable for video controls in various local, but also for remote monitoring of a house, a children's room, etc.. The transmission can easily be received on any TV.
suf cient to place a mini-radio transmitter so you can listen to the conver-sations and the sounds that emanate.
There are, to this end, a myriad of devices, more or less miniaturized, based on dif ferent technologies.
However, these systems successfully used by profes-sionals, or even by amateurs, there's something missing now we can add, without too many complications, thanks to modern technology: video.
In fact, if in many cases, listening is more than suffi-cient, we can not deny that see what happens, even if through a camera is insane decision better than hearing only. See also means having a cer tainty immediately on what REALLY happens in the in-law surveillé.C is to meet this need to know for certain that we have designed and built the mini-transmitter
audio / video described in these pages.
This is a small device similar to a television transmitter, which can be installed everywhere, disguised as needed. This is ideal for many applications, both in industrial (eg, a dangerous place or sensitive), or in domestic premises (such as a child's room), etc..
The assembly was designed to work with a food-tion sector. The transmitter should be placed close to a 220 volts.
This circuit is dif ference of other issuers like the presence of a remote activation by the in-intermediate codée.L a radio transmitter television is normally off until the time where the person who wants to put in monitoring service using a small handheld radio transmitter (remote control). This solution allows to control several places as long, of course, that every place in monitor has a transmitter. However, issuers using the same video channel, they can be activated qu'alternati-tively. To do this, simply use a ser-radio multi-channel video programming of each transmitter to be activated by an appropriate code Study the diagram:
The video signal is assigned to the hybrid module U5, the popular TX-Aurel AV, we already know, to be used in a previous project.
We are dealing here with a com-plete transmitter audio / video on the operating frequency of 224.5 MHz (channel 12-band III) with a floor of HF just 2 milliwatts, but capable of being received by any TV set within 50 to 100 meters.
This module accepts a composite video signal directly to 1 volt of 75 ohms on a standard CCIR or PAL
It can thus be directly controlled by a small CCD or CMOS camera, such as those found in present-ing trade.
To simplify the connections we have planned a 3-point terminal block to provide 12 volts necessary to power the camera and the video signal input.
Certainly, there are cameras which glows lie in 5 volts. It is advisable to have a second controller, identical to U4, wired in a similar manner, so as to have 5 volts stabilized independent of the stage HF. In this case, it is important not to use the points "+" and "-" terminal of the camera.
Regarding the audio, the voices and sounds are captured by the intermediary of a small microphone. We have provided a signal amplifier, formed by the two operational amplifier and U6a U6b, sized to ensure a very high sensitivity and fidelity that you can appreciate.
MIC terminals, apply a preamplified microphone capsule with two son (the "+" is the nodal point R13 / C13) so that the low signal generated, joining the entry of U6a, mounted as a variable gain inverting amplifier (through the R9 trimmer, it is possible to vary between 1 and 230 times). Of this amplifier, the signal passes through the second floor almost identical.
This last stage, the outgoing signal t with a level 10 times higher and can adequately control pin 2 of the hybrid module TX-AV, the audio input on.
Note that the two operational amplifier operating in single-supply, therefore it was necessary to bias the non-inverting pin half the potentially supply (5: 2 = 2.5 volts) so as to have 2.5 volts at rest on the outgoing tie each of them. This allows to have a good trip signal on the two alternatives.
The two floors are isolated from the DC by the capacitors C13, C12, C10 that allow the BF seu-tion by blocking the DC component.
The preamplifier and the hybrid module are powered with 5 volts supplied by the stabilized-regulating U4, (7805). It takes the power supply units on the main line to 12 volts down the cathode of the protection diode D1.
Note that the issuer does not functioning at all times because even if it receives the +5 volts, the common line (ground) is not constantly connected to the negative input.
This function is entrusted to the transistor T1, which goes into conduction (ON) by pre-senting a minimum resistance (Rdson <0.1 ohm) when polarized at his door, with a positive level.
The MOSFET switch is static that the receiver uses radio-demand for power to the video transmitter.
Let's see how we in reference fied in the left diagram electrical.
A second module CMS Aurel NB-EC, U1, tuned to 433.92 MHz-mats are used as high-frequency receiver.
The radio signal received by the antenna is amplified and demodulated in amplitude. It is then shaped so as to obtain an output pulse train as much as possible identical to that sent by the transmitter.
Spindle 14 (outgoing tie the module), the signal is sent to the integrated circuit or UM86409 MM53200 used as decoder (pin 15 is at logic 0), its role is to interpret the coded signal.
Its pin 17, which is normally high, goes to zero when the input pin (pin 16) comes a code produced by a transmitter with a 12-bit encoder is posi-tioned in a similar way for DS1 and DS2.
In practice, the decoder is set seu-tion if the received signal was transmitted by a transmitter with dip-switches are placed one by one like those in our circuit.
For example, if the issuer in the first ten dip-switches are closed, others open, and in the receiver we all dip switch DS1 and DS2 to open every possible command will not work.
If instead, we all dip switch DS1 in both closed and open DS2, when an order is sent by the transmitter, the decoder U2 activates its output by issuing a negative pulse.
Transmitter radio control has been studied not to consider the logic level due to the activation, but release the front. Thus, as the push button transmitter is pressed, the output of UM86409 remains at zero, its rela-ery, the level goes to logic 1. It's really at that time, the switch U3 receives the clock signal (transition 0 / 1) and reverse the state of the outputs Q and Q bar.
Note that, due to the ef fect of the network C2 / R14, U3 is reset when the circuit is powered. So, initially, the flip ends up with pin 1 (Q) to 0 and pin 2 (Q bar) high.
Following the first pulse, the situation is reversed, Q goes to the high state, which allows the transistor T3 to become conductive. The collector of it happening practically in potentially polarizing mass and also T2 (which is a PNP).
A positive level is thus transmitted to the MOSFET, it is on, becomes the way, and thus closes the return of power to the video transmitter.
The transmitter is thus activated and begins transmitting images captured by the camera and the sounds picked up by the microphone.
All this remains in the state until the button of the remote control transmitter is pressed, then release-market a second time. Then, the output of U2 goes back to logic zero giving a new pulse to flip-flop. Pin 1 of U3 is positioned at the low state, T3 and T2 are off and the MOSFET, since it no longer receives polarization. The drain is isolated and
Section TV is off.
The por tee remote control is about 50 to 100 meters in UTI-reading a small transmitter standard 10 milliwatts and we think this is sufficient because it is also the range of the transmitter audio / video.
It makes sense to control the functioning of the device where the images are viewed, in order to control immediately if reception is correct.
List of components:
FT2 September 9
R1 = 1.5 k?
R2 = 10 k?
R3 = 220 k?
R4 = 10 k? R5 = 10 k? R6 = 10?
R7 = 10 k?
R8 = 2.2 k?
R9 = 470 k? Trimmer
R10 = 4.7 k?
R11 = 47 k?
R12 = 4.7 k? R13 = 4.7 k? R14 = 22 k?
R15 = 22 k?
R16 = 10 k?
R17 = 2.2 k?
C1 = 100μF 16 V electrolytic
C2 = 22 uF 25 V electrolytic
C3 = 100 pF ceramic
C4 = 10 nF ceramic
C5 = 10 nF ceramic
C6 = 470μF 16 V electrolytic
C7 = 100μF 16 V electrolytic
C8 = 100nF multilayer
C9 = 10 uF 63 V electrolytic
C10 = 100 nF multilayer
C11 = 100 nF multilayer
C12 = 100 nF multilayer
C13 = 10 pF ceramic
C14 = 10 uF 63 V electrolytic
C15 = 10 uF 63 V electrolytic
C16 = 100 nF multilayer
C17 = 1000 pF ceramic
D1 = 1N4007 Diode
DZ 1 = 5.1 V zener diode
T1
= Transistor mosfet BUZ11
T2
PNP Transistor = BC557
T3
= NPN Transistor BC547
U1 = 433 MHz module Aurel
NB-CE
U2 = Integrated UM86409
U3 = Built 4013
Regulator U4 = 7805
U5 = Module Aurel AV TX-DS1 = 10 Dip switch DS2 inter = inter Dip switch 2
MIC = microphone preamplified
2 outputs
ANT1 Antenna = 433 MHz
ANT2 Antenna = 224 MHz
Misc:
1 support 2 x 9-pin
1 support 2 x 7-pin
1 support 2 x 4-pin
2 terminals 2 contacts
A terminal 3 contacts
No comments:
Post a Comment