Figure 1.There are many diagrams of transmitters and infrared receivers. Whoever has done some immediately recognized that the scope rarely exceeding 2 meters. In addition, if a light is on, it is now almost impossible to get a signal because the receiver diode is saturated. We propose in this paper, an audio transmission via IR, simple, efficient, and which does no harm, economical!
As you know, a headset infrared is used primarily for listening without disturbing the neighbors live on the radio or television.
Once the information about the infrared transmitter connected to the headphone jack on the radio or TV, you can listen to any program, while remaining comfortably in his chair, without disturbing those who play or who read .
Since transmission is ensured by a beam of invisible light, the photodiode receiver shall, if possible, be oriented emitting diodes. It also requires that the power is sufficient for the receiver diode is not blinded by any light sources.
To make a transmitter and a receiver infrared-functioning, we must have recourse to circuits a little more technically sophisticated than those we usually encounter, such as we now offer. If you have already made such an arrangement compare its scheme to figures 2 and 6 and you'll notice the difference easily!
Immediately be noted that the scope of these invisible rays is about 6 meters. However, for the increase, it would suffice to place lenses in front of the diodes. With the infrared, you can also make interesting experiments, for example, by making them think about moving metal parts, on mirrors, etc..
It is understood that if you put one hand in front emitting diodes or diode before receiving the infrared beam is interrupted.
The transmitter stage
Figure 2 : Electrical diagram of the transmitter stage. The diode DL1 indicates that the transmitter is powered, the diode DL2 indicates that the audio signal exceeds the maximum allowed. DTX1 emitting diodes, infrared DTX3 DTX2 and are those connected to the collector of transistor TR1.
Figure 3: As a mono signal to be applied to both internal pin jack connected to the transmitter input, it is necessary to weld two resistors 1000 ohms 1 / 8 watt.
Figure 4 : Pin 3 of integrated circuit IC3 outputs a square wave with a duty ratio of 90%. When the square wave happening on the logic level "0", the collector of transistor TR1 controls the infrared-emitting diodes with a duty ratio of 10%.
Figure 5: Photo of the prototype transmitter stage. Below, you can see the three infrared emitting diodes.To make a decent floor modulated FM transmitter, just two ICs, one transistor and three infrared diodes (see Figure 2).
The signal to be applied to the input jack BF is taken from the headphone jack of a radio or TV, through a jack.
As we pass the signal is the monophonic, we need to connect two resistors of 1000 ohms 1 / 8 watt to both internal contacts of the jack as shown in Figure 3.
The audio signal passing through capacitor C8 of 1 microfarad, joined the trimmer R3 used to assay the amplitude of the audio signal to be applied to the non-inverting input of first operational amplifier IC2 / B, used as a preamp and equalizer preemphasis.
The amplified signal is then applied to pin 5 of IC 3, a NE555, through the resistor R14 and capacitor C14.
The NE555 is used to modulate the frequency of the square signal that we collect on the output pin 3.
By maneuvering the trimmer R12 10 kilohms placed on pin 7, we can vary the carrier frequency, a minimum of 180 kHz up to 200 kHz, so you can easily tune to the frequency on which is keyed receiver.
The secret of this transmitter is located entirely on the integrated circuit IC3, which allows us not only to change the tuning frequency and modulating the carrier generated in FM, but also provide on pin 3, a square wave with a duty ratio of 90% (see Figure 4).
This helps us to control the transistor TR1 is used as constant current generator, to power the three infrared emitting diodes connected in series with the collector.
When the signal is squared for a 90% time at logic "1", the transistor TR1, which is a PNP, not drive. By cons, when the signal switches to logic level "0" for a period of 10%, the transistor becomes conductive and provides power to the three infrared diodes.
In this circuit, the operational amplifier IC2-A is used to control the audio signal used to modulate the integrated circuit IC3 not exceed the maximum permitted level, to avoid distortion.
If, during modulation, you notice that the LED lights DL2, you should turn the cursor trimmer R3, or lower the TV volume to its extinction.
This infrared transmitter is powered with a stabilized voltage of 12 volts, we collect the power stage consists of the transformer T1, bridge rectifier RS1 and stabilizer of the integrated circuit IC1.
The receiver stage
Figure 6 : Electrical diagram of the receiver stage. To receive and demodulate the FM signal to the frequency of 180 to 200 kHz, use the integrated circuit NE615 (see Figure 7).
Figure 7 : Block diagram of the integrated circuit NE615. The mixer stage and the oscillator stage of the integrated circuit are not used in this application.
Figure 8 : Installation diagram of components of the transmitter stage. When folded L-shaped legs of infrared emitting diodes in order to insert them down on the PCB, you must ensure that the tab is longer "A " is placed to the left. Similarly, when you place the ZTX753 transistor (TR1 see) on the PCB, you should check that the flat part of his body is pointing toward C5. The pinout of the transistor, reproduced at right, is seen from below.
Figure 9 : The pinouts of the integrated circuit NE555 TL082 and viewed from above, pointing it left their mark positioning U.
Figure 10: Photo of the prototype stage transmitter mounted in its case. As you can see, the switch startup S1 is mounted on the rear panel.
Figure 11: Photo of the prototype receiver stage mounted in its case. We must practice the holes for the diode and XRD for the diode DL1, headphone jack and a cutout for the potentiometer knob.
Figure 12 : Installation diagram of components of the receiver stage.Note: The installation completed but with only the receiver on, you hear a loud enough breath in the helmet. If you hear nothing, you must unsolder the inductance JAF1 and resolder in the other direction to reverse the direction of its internal coil.
In the bottom photo, you can see how this receiver once the installation is completed.
Figure 13 : Photo of the prototype receiver plate.Notice the ground plane under the inductors.
Figure 14 : Before fixing the photodiode receiver on the circuit board, you must determine what is the tab "A" and the tab "K".
Figure 15: Mounting the transmitter and receiver are finished, you can do interesting experiments on the propagation of infrared rays.Note that the maximum range of these rays hardly exceeds a distance of 6 meters.
Figure 16 : Pinouts of the integrated circuit NE5532 seen from above and two transistors BC547 and BC328 viewed below.
Figure 17 : The two pins that are outside the body of the potentiometer R14 are those of the switch S1.If we have a transmitter capable of generating an infrared beam tuned to 180-200 kHz FM modulated, we also need a receiver capable of capturing the frequency and then the demodulated so as to collect on its output, a signal BF undistorted.
To capture this signal, we use a diode infrared-sensitive receptor, type BPW34, it can be replaced with a model with similar characteristics. As shown in Figure 6, this diode is connected between the collector and the mass of the PNP transistor, TR1 referenced.
TR1 transistor, wired in this configuration, amplify any signal, but handles a lot more useful function because it prevents the receiving photodiode DRX is saturated, where she would be hit by an intense light .
The modulated signal, received by the photodiode passes through the capacitor C3, reached the base of the transistor TR2 which makes its amplification.
The collector of the transistor, we find an LC circuit (see CA and JAF1), tuned to the frequency of 200 kHz, thereby making the entrance very selective.
Thus, the input pin 18 of integrated circuit IC1, as does the single frequency of 200 kHz.
To calculate the tuning frequency of this filter, it is possible to use the following formula:
kHz = 159 000 : √(picofarads x microhenry)
Looking at the list of components, we can note that the JAF1 has a value of 220 microhenrys and the capacitor C4 has a value of 3300 picofarads.
By placing in the above formula the values of C4 and JAF1, this circuit will tune the frequency of:
159000: √(3300 x 220) = 186,60 kHz
Considering the tolerance of the capacitor C4 and inductor JAF1, this circuit will agree on 180-200 kHz, but do not worry about that because we can fix this by turning the tolerance of the transmitter trimmer R12 .
Let us now integrated circuit IC1, which is, in fact, a complete FM receiver referenced NE615, manufactured by Philips (see block diagram Figure 7).
We do not use the first mixer or oscillator in this circuit (see Pin 1, 2, 3, 4 and 20).
By cons, we use the amplifier stage MF and FM demodulator.
As we have already noted, the frequency of 200 kHz, taken from the collector of transistor TR2 is sent to pin 18 of IC1 to be amplified.
The amplified signal coming out of the pin 16 passes through a filter passebande tuned to 200 kHz, consisting of inductors and JAF2 JAF3 and capacitors C12, C13 and C14. Afterwards, he was sent on pin 14 to be demodulated.
The output pin 9 we take our audio signal, which is applied, through resistor R11 to the base of the transistor TR3.
The signal that we collect on its transmitter before being applied to the volume potentiometer R14, undergoes filtering through resistor R13 and capacitor C25.
As this signal is not able to drive a low impedance load such as a helmet, we magnify a bridge output stage, implementing an integrated circuit NE5532, which has the advantage of consuming a stream ridiculous.
As we can see from the diagram in Figure 6, the two earphones of the headset, are directly connected to the outputs of IC2 IC2-A and-B.
Both headphones to stereo headphones to be connected in series, and to do this, simply do not connect to ground the metal portion of the rear jack.
In practical realization, we have already planned not to connect to ground the body of the female connector.
In this way, the two
find themselves connected headphones
series.
This receiver is supplied with a standard 9 volt battery.
The supply voltage of the integrated circuit IC1 must never exceed 8 volts, we plan to lower the 9-volt battery of about 1.3 volts, connecting in series two silicon diodes (see DS1 and DS2) .
Simple and effective!
Realization of the transmitting stage
All components of the transmitter stage are mounted on the circuit board as shown on the wiring diagram in Figure 8.
The first components to implement, are both carriers of the integrated circuits IC2 and IC3 ensuring their orientation.
Solder all resistors and near IC2, trimmer R3 50 kilohms, which is recognized by the number 503 marked on its body.
Nearly IC3, insert the trimmer R12 10 kilohms, which is recognized by its markings 103.
After these components, you can insert all diodes, directing their ring, as is clearly shown in the drawing of Figure 8.
Continue the installation by the installation of two ceramic capacitors, polyester capacitors, then 7 and finally the 6 electrolytic capacitors in the polarity of their legs + and -.
At this point, take the transistor TR1 and check which side of his body slightly rounded corners (see Figure 8), because this side must be forward-emitting diodes.
The integrated circuit IC1 stabilizer is placed between the two electrolytic capacitors C1 and C4, guiding the metal part of its case to the transformer T1.
On the left of C1, insert the bridge rectifier SR1 the polarity of the two legs + and -.
Finally, mount the transformer T1 and on each side, the terminals 2 cones.
Use the terminal on the left to connect the wire from the mains 220 volt terminal block to connect the two straight son who start switch S1 commissioning.
Insert the integrated circuit TL082 in suppor t and the integrated circuit IC2 NE555 IC3 support in directing their cue-keyed U-shaped as shown in the diagram wiring practice Figure 8.
To complete the installation, insert DTX1 emitting diodes, and DTX2 DTX3 on the circuit board by folding the two legs "L".
During the completion of this operation, make sure the leg is shorter these diodes, in this case the cathode "K", well directed
right. If you are wrong, the issuer will not work.
This rule applies equally to both diodes DL1 and DL2, which you must comply with the polarity of their two legs "A" and "K".
When you connect the shielded cable to pin jack, do not forget to mount the two resistors of 1000 ohms 1 / 8 watt, as shown in Figure 3.
The PCB is then placed inside the plastic case, after setting the two chrome flanges, for receiving the two diodes DL1 and DL2, on the front panel and inverter S1 on the rear panel.
Do not insert the plug into a 220 volt without first carefully checking your work and have attached the circuit board inside the cabinet.
Indeed, the copper tracks located near the transformer T1 are covered by the 220 volt industry, and if you accidentally come to the touch, you could receive a dangerous electric shock.
Realization of the receiving stage
All components of the receiver stage are mounted on the circuit board as shown on the wiring diagram in Figure 12.
As to the transmitter circuit, the first two components to implement, are the two carriers for integrated circuits IC1 and IC2.
You can continue with the implementation of all the resistors and the potentiometer R14, whose body out of the two contacts of the switch S1, as you can see in Figure 17.
These two operations are completed, insert the two diodes DS1 and DS2, directing them to the left ring.
Place the jack for headphones, ceramic capacitors, polyester and electrolytic respect to the latter, the polarity of their feet.
Having reached this point, take the inductance JAF1 on the body which is marked number "1K", and insert it near the transistor TR2.
Then insert the two inductors and JAF2 JAF3 on the body which is labeled the figure "3.3 K", and put them near the integrated circuit IC1.
Then attach the fourth inductor JAF4, marked "470" on the right of the integrated circuit IC1 (see Figure 12).
Before putting in place the transistors in their proper position, check the reference well marked on their bodies.
Place the BC328 which is a PNP at the top right side of the PCB (see TR1), guiding down the flat part of his body.
BC547 transistor, a PNP, is placed high on the left side of the PCB (see TR2), orienting the flat side of his body upward.
Even the last transistor, which is also a BC547 is mounted near the potentiometer R14, guiding left the flat part of his body.
Now, we must weld the receiving photodiode XRD, elevated on two small pieces of rigid son taking care not to invert the cathode "K" and the anode "A" (see Figure 14).
The diode DL1, which indicates whether the receiver is turned on or off, is being folded up after the "L" both legs, while checking that the longer that of the anode "A" is oriented making outgoing part of the helmet.
To complete the assembly, place the knob on the potentiometer and connect both the son taken to receive the battery.
Insert the two integrated circuits IC1 and IC2 in their respective support, respecting the meaning of their benchmark-keyed, as shown on the layout diagram of Figure 12.
Component List TX
R1 = 820 Ω
R2 = 12 kΩ
R3 = 50 kΩ trimmer
R4 = 22 kW
R5 = 820 Ω
R6 = 100 kΩ
R7 = 22 kW
R8 = 4.7 kΩ
R9 = 68 kΩ
R10 = 1 kΩ
R11 = 1 kΩ
R12 = 10 kilohms trimmer
R13 = 1 kΩ
R14 = 4.7 kΩ
R15 = 15 kΩ
R16 = 2.2 kΩ
R17 = 1.5 Ω
R18 = 1.5 Ω
C1 = 470 uF electrolytic
C2 = 100 nF polyester
C3 = 100 nF polyester
C4 = 100 uF electrolytic
C5 = 100 uF electrolytic
C6 = 100 nF polyester
C7 = 10 uF electrolytic
C8 = 1 uF polyester
C9 = 2.2 uF electrolytic
C10 = 1 nF polyester
C11 = 68 pF ceramic
C12 = 180 pF ceramic
C13 = 100 nF polyester
C14 = 10 uF electrolytic
C15 = 1 nF polyester
RS1 = Bridge Rectifier 100 V 1 A
DS1 = Diode 1N4150
DS2 = Diode 1N4150
DS3 = Diode 1N4150
DL1 = Diode LED
DL2 Diode LED =
DTX1 infrared diode-3 = TX CQX89
ZTX753 PNP Transistor TR1 =
IC1 = Integrated L7808
IC2 = TL082 Integrated
IC3 = Integrated NE555
T1 = Transformer. 3 watts (T003.02) sec. 0-8-12 V 0.2 A
S1 = Switch
Component List RX
R1 = 1.2 kΩ
R2 = 100 kΩ
R3 = 100 kΩ
R4 = 12 kΩ
R5 = 220 Ω
R6 = 680 Ω
R7 = 100 kΩ
R8 = 100 kΩ
R9 = 100 kΩ
R10 = 3.3 kΩ
R11 = 4.7 kΩ
R12 = 1 kΩ
R13 = 15 kΩ
R14 = 47 kilohm pot. log.
R15 = 10 kilohms
R16 = 10 kilohms
R17 = 100 kΩ
R18 = 4.7 kΩ
R19 = 22 kW
R20 = 22 kW
R21 = 22 kW
R22 = 4.7 kΩ
R23 = 10 Ω
R24 = 10 Ω
C1 = 47 uF electrolytic
C2 = 220 pF ceramic
C3 = 470 pF ceramic
C4 = 3.3 nF ceramic
C5 = 10 nF ceramic
C6 = 10 uF electrolytic
C7 = 10 nF ceramic
C8 = 10 nF ceramic
C9 = 47 uF electrolytic
C10 = 100 nF ceramic
C11 = 100 nF ceramic
C12 = 220 pF ceramic
C13 = 820 pF ceramic
C14 = 220 pF ceramic
C15 = 100 nF ceramic
C16 = 100 nF ceramic
C17 = 100 pF ceramic
C18 = 47 pF ceramic
C19 = 10 nF ceramic
C20 = 820 pF ceramic
C21 = 820 pF ceramic
C22 = 100 uF electrolytic
C23 = 100 nF polyester
C24 = 100 nF polyester
C25 = 2.2 nF polyester
C26 = 1 uF polyester
C27 = 1 uF polyester
C28 = 100 nF polyester
C29 = 10 uF electrolytic
C30 = 10 uF electrolytic
C31 = 10 uF electrolytic
Self JAF1 = 220 uH
Self JAF2 = 3.3 mH
Self JAF3 = 3.3 mH
Self JAF4 = 470 uH
DS1 = Diode 1N4150
DS2 = Diode 1N4150
DL1 = Diode LED
XRD = X-ray diode infrared BPW34
TR1 = BC327 or BC328 PNP Transistor
TR2 = BC547 NPN Transistor
TR3 = BC547 NPN Transistor
IC1 = NE615 Integrated
IC2 = NE5532 Integrated
Switch on S1 = R14
The adjustment
So that the signal can be received, must necessarily give the frequency of the transmitter with the receiver. As we have already said, it can be between a minimum of 180 kHz and a maximum of 200 kHz.
To make this adjustment, we recommend you do the following:
Connect the plug from the transmitter to the headphone jack of the radio or television. Adjust the volume of this unit on an average value, then turn the trimmer R3 transmitter until the LED lights DL2.
This condition is obtained, slightly lower the volume until it is extinguished.
Take the infrared receiver and place it at about 1 meter away from the transmitter, steering diodes emitting diode to the receiver.
Now, slowly turn the cursor trimmer R12 to the transmitter until you hear the signal in the headphones.
To tune with greater precision the frequency emitted by the transmitter, move away from 3 or 4 feet, then edit the cursor trimmer R12.
The maximum range you manage to achieve is around 6 meters. When you exceed this distance you will notice it immediately because the audio signal, and more ease, be accompanied by a slight noise.
If you can not pick up any signal, you might mistake for not pointing to the right of all short legs emitting diodes, or have connected to the right instead of left leg "A" BPW34 the receiving diode.
No comments:
Post a Comment