The VHF repeater for remote control allows you to increase dramatically the range of your remote TV or stereo, etc.. and even control a device located in another room. So you can reach all devices with infrared control as STB, DVD player, VCR, AV system ...
Those of you who built the TX / RX AV 2, 4 GHz EN1557-1558 will certainly be interested in the RF repeater infrared remote control that offers this article. Indeed, when we published the analysis and construction of the transmitter / receiver audio / video, we expected an application to transmit (Wireless of course) video signals taken from the SCART TV decoder, this application can be very useful if you wish to transmit the output of a decoder connected to the TV lounge to a second TV in another room (bedroom or kitchen ...). Thus, it is possible to follow television programs wherever you are in the house without having to unplug the plug-move-top box (or VCR or DVD player ...) and wireless!
But in this case, your IR remote (which controls the cable box or VCR or DVD player ...) is irrelevant (since these remotes require a short distance and bond mostly "direct vision" barrier-free), you would then have to move to control the device (decoder ...) located in a another room.
Well, editing the article offers is designed to mitigate the latter problem. Indeed, it is intended not only to increase the reach of your IR remote control, but to make it insensitive to the obstacles interposed, such as walls or doors of the house. This insensitivity to the obstacles is the fact that this repeater throws a "bridge" radio (VHF) between the transmitter and receiver IR remote. This repeater or bridge consists of a TX to place 1 or 2 meters from the remote (the little box manual, which is actually an IR transmitter) and a RX to place near the unit to order (this latter contains the IR receiver hidden). The role of the TX modulation to receive from the remote control and to route the signal by radio (hence through domestic obstacles) to a RX restoring the signal to remote receiver for controlling the remote device. The radio signal carrying the bridge is in VHF and 350 MHz range is about 50 meters in free space (ie what do the garden toward the house). We mainly talked about the television receiver, but it remains valid repeater for remote control and despite any obstacles to IR remote control device (see Figures 1-4).
Figure 1: The remote repeater consists of a transmitter module which receives the TX signal from the IR remote and turns it into a signal and a VHF radio receiver module which converts it back to RX signal IR capable of controlling any device with, of course, a system of infra-red remote control.
Figure 2: RF repeater for remote control allows you to remotely activate the decoder, the VCR or DVD player located in another room.
So if you have an additional satellite antenna jack, you can watch your favorite programs quietly in the garden.
Figure 3: If you are not making additional antenna which connect the TV, you can also watch television outside your home using our transceiver AV EN1557-1558, you simply connect your TV to the AV receiver EN1558.
Figure 4: If you wish to follow a television program, or watch a DVD or a video, you must link our audio-video transmitter to EN1557 SCART socket of the decoder, DVD player or VCR as shown in FIG.
Figure 5: TV remote control signal generates an infra-red (IR) encoded into digital form (it modulates a carrier of about 50 kHz). 
Figure 6: The signal generated by the remote module is converted by the transmitter TX in an identical signal modulating the carrier both VHF 350 MHz. 
Wiring diagrams The wiring diagram of the TX is shown in Figure 7 and the RX of Figure 10. The transmitter TX
Each time you press a button on the IR remote to send commands to the device (eg the red button to start the decoder) a coded signal is transmitted (sequence of logic levels 0 and 1, variable depending on the function you want to enable, for example starting or choice of channel 2 ...). For reliability, the code is amplitude modulated onto a carrier frequency of 50 kHz, as shown in Figure 5 (approximately, because the frequency changes slightly depending on manufacturer and type of remote). This signal from the IR remote is sensed by the diode detector (or receiver) IR BPW41 (DRX1, see wiring diagram figure 7) at the entrance of the TX Radio EN1628 we analyze. This diode is connected to pin 13 of IC1 / A, an inverter mounted with R1 amplifier gain about 50. The output pin 12 is carried by C1 low-pass filter that eliminates JAF1 C2/C3 + carrier at 50 kHz present in the signal from the remote to keep only the code. In turn the inverter IC1 / B moderately amplifies the signal which is then sent to two inverters IC1 / C and IC1 / D which are the ultimate signal quadrature. A pin 6 of IC1 / D is connected to DL1, flashing, indicates the correct reception of the signal.
The signal is routed from the pin 6 to the input of IC1 / C and IC1 / F mounted buffers (Pads) to increase the current supplied to the next stage: an oscillator consisting of TR1, with the half turn printed L1 by C8 and C9 adjustable. When the signal at the output of IC1 / F, pin 4 is at logic low, the oscillator stage does not oscillate and therefore no signal reaches the antenna, when the signal goes to logic high, Upstairs oscillator starts to oscillate at a frequency of 350 MHz. At the output of the antenna, so we will have a signal reproducing exactly the code received from the remote, but this time on a modulated carrier at 350 MHz as shown in Figure 6.
The circuit is simply powered by a 9 volt battery 6F22 whose voltage reaches IC1 and the oscillator stage through JAF2 whose function is to eliminate any return to the HF diet.
The RX
The signal received by the antenna is sent to the super-regenerative receiver constituted by the transistor TR1, by C3, by the half turn printed L1, by C4, C5, C6 and that JAF1 detects the signal by eliminating the carrier at 350 MHz. This
RX EN1629 super-reaction characterized by high sensitivity and low selectivity, characteristics that allow the circuit to receive the best signal from the TX EN1628 described above (even in non-optimal conditions).
After being detected, the signal is routed to the non-inverting amplifier stage IC2 / A, which amplifies it 200 times and gets rid of any residual HF.
Pin 7 of IC2 / A is connected to the non-inverting input of IC2 / B which is the quadrature circuit. DL1, connected to the output of IC2 / B, indicates, by its flashing, the signal is received.
Its cathode is connected to pin 4 of IC 3, a mounted NE555 in astable multivibrator, able to oscillate at a frequency adjustable between 12 and 68 kHz by trimmer R16.
When the signal at the output of IC2 / B is at logic high level, IC3 oscillator and this signal goes to logic low, it stopped flapping.
The frequency produced at pin 3 of IC 3 is supplied to the IR emitter diode CQX89 (DTX1, see wiring diagram figure 10) which recreates the output exactly the same code as that emitted by the remote and adjusted on a variable frequency between 12 and 68 kHz (able to operate the decoder or other device with such a system of infra-red remote control).
If the broadcast signal by the TX and the reception of that signal by the RX are correct in pointing the remote toward the IR TX and pressing any button, the DL1 DL1 TX and RX shall flash in perfect synchronization.
This circuit is also powered by a 9 volt battery 6F22 whose voltage reaches IC2 and IC3; floor super-regenerative receiver receives the 5 V needed for the output of IC1 78L05 regulator.
Figure 7: Circuit diagram of transmitter module TX. The signal from the remote is sensed by the infrared receiver diode DRX1 then converted by the circuit into a signal modulated on a carrier at 350 MHz transmitted by the antenna.
Iist
R1 ...... R2 150 k
...... 10 k R3
...... 10 k R4
...... 100 k R5 ...... R6 180 k
...... R7 330 K ...... 47 k R8 ...... 1 M R9 ...... 1 k R10 ..... 10 k
R11 ..... 39 C1 ...... 10 uF electrolytic C2 ...... 10 uF electrolytic
C3 ...... 10 nF polyester
C4 ...... 1 uF polyester
C5 ...... 100 nF polyester
...... C6 10 uF electrolytic
...... C7 10 nF ceramic
C8 ...... 4.7 pF ceramic
C9 ...... adjustable from 1.2 to 6 pF
JAF1 .... 47 mH choke
JAF2 .... 10 uH choke L1
...... self "strip-line (printed line)
XTAL .... 4 MHz quartz
DS1 ..... 1N4148
DL1 ..... LED
DRX1 .... IR RX LED BPW41
TR1 ..... NPN 2N918 IC1
..... CD4069
S1 ..... switch
Figure 8: Pinouts of CD4069 seen from above, from below the 2N918, LED front view and the IR receiver diode to the photosensitive face (that which has no marking) .
Figure 9: Pinout NE5532 NE555 and seen from above and mark-U-notches to the left.
Figure 10: Diagram of the receiver module RX. The 350 MHz signal is detected by the super-regenerative circuit formed by TR1, L1 and C2, C3, C5 and C6 and concerti in an IR signal modulated on a carrier between 12 and 68 kHz, any device capable of operating equipped with an infrared remote control. 
Iist R1 ...... 10 k R2 ...... 47 k R3 ...... 2.2 k R4
...... 1 k R5 ...... R6 10 k
...... 12 k R7 ...... 22 k R8 ...... 4.7 M R9 ...... 10 k R10 ..... R11 470 k
..... R12 10 k ..... 2,2 M R13 ..... 1 k
R14 ..... 1 k
R15 ..... 10 k
R16 ..... 50 k
R17 ..... 100
C1 ...... 1,5 pF céramique
C2 ...... 1 nF céramique
C3 ...... 4,7 pF céramique
C4 ...... 1 nF céramique
C5 ...... 4,7 pF céramique
C6 ...... 1,5 pF céramique
C7 ...... 1 nF céramique
C8 ...... 10 μF électrolytique
C9 ...... 2,2 pF céramique
C10 ..... 10 μF électrolytique
C11 ..... 10 μF électrolytique
C12 ..... 100 nF polyester
C13 ..... 10 μF électrolytique
C14 ..... 100 nF polyester
C15 ..... 1 nF polyester
C16 ..... 100 nF polyester
JAF1 .... 1 uH choke L1
...... self "strip-line (printed line)
DL1 ..... LED
DTX1 .... IR diode TX CQX89
TR1 ..... NPN 2N918 IC1
..... 78L05 IC2
..... NE5532
IC3 ..... NE555
S1 ...... switch
Figure 11: Pinouts LED front view of the NPN 2N918 and regulator viewed below and the IR emitting diode front view as the LED.
Figure 12: When mounting the IR receiver diode BPW41, be sure to look outward face sensitive (that is to say that that is not marked).
Figure 13a: Schematic implementation of the components of the transmitter module TX viewed from the side components and welds. Note, this last part, the insertion point of the antenna. 
Figure 13b: Drawing, to scale 1:1, the PCB of the transmitter module TX. 
Figure 14: Photograph of a prototype transmitter module TX. We see the adjustable capacitor C9 and inductive line (self printed) L1.
Figure 15a: Diagram implementation components of the receiver module RX viewed from the side components and solder side.
Note on the latter side, the insertion point of the antenna.
Figure 15b: Drawing, to scale 1:1, the PCB module RX.
Figure 16: Photograph of a prototype receiver module RX. We see the R16 potentiometer for adjusting the frequency of the signal emitted by the IR diode DTX1 and inductive line (self printed) L1.
The practical Nothing is easier than to complete the construction of these two modules as HF, both the TX and RX have their self already printed on the circuit (L1). The two plates are so similar, as shown in Figure 17 and you can consider mounting them together ... We will, however, as we describe to mount a plate after another. 
The transmitter TX When you purchased, or you have made the small-sided printed circuit 13b which gives the scale drawing 1: 1, mount the first integrated circuit support and check your soldering (or short-circuit between tracks or pads or cold solder joints) and continue through the resistors, the diode (ring to C1), the coiled coil JAF2, self JAF1 molded, ceramic capacitors, polyester and electrolytic (observe polarity of the latter), transistor (pin-keyed to reference R11), the adjustable capacitor C9, diode IR DRX1 (unmarked face outwards from the plate), the LED DL1 (anode- pin to the longest-C7), the son taking 6F22 (red +, black to -9 V) and finally the slide switch S1. The antenna is soda copper side, as you can voirsur Figure 13a. Once the final weld is completed, insert into the socket IC1, repèredétrompeur U to C6.
With the help of figures 13a and 14 (plus parts list) you will come out very well.
Receiver TX
When you purchased, or you have done it single-sided printed circuit board (slightly larger than the previous) with Figure 15b shows the drawing to scale 1:1 , mount the first two brackets of integrated circuits and check your soldering (or short-circuit between tracks or pellets or cold solder joints). Continue by resistance, self JAF1 molded, ceramic capacitors, polyester and electrolytic (observe polarity of the latter), transistor (pin-keyed reference to C5), the regulator IC1 (flat-keyed to reference C11), the R16 trimmer, the LED IR DTX1 (anode pin-longest-left), son of the decision-6F22 (red +, black to -9 V) and finally the slide switch S1. The antenna is welded copper side and also the LED DL1 (anode-longest-pin towards the antenna) as shown in Figure 15a. Once the final weld is completed, insert IC2 and IC3 into their racks, cue-U notches respectively to C12 and C14. With the help of figures 15a and 16 (plus parts list) you will come out very well.
Installation in enclosures
Again, with Figure 17, you will hardly go wrong! In both cases specific plastic plates are fixed to the bottom with a protruding pin. The sides are pierced for the passage of the LEDs and switches (TX and RX) to that of the IR diode receiver (TX) and the IR emitting diode (RX). For two modules, one slot for the battery 6F22 9 V
tests and adjustments
To address your two modules TX and RX, follow the following procedure:
- Adjust trimmer R16 RX mid race.
- Put the TX and RX modules side by side. - Take the IR remote that you use, for example, to operate the decoder and point it at the TX module. Press a button (eg the start-up). TX LED module will flash to confirm that the signal from the IR remote is well received by the TX. - Continue to operate the remote repeatedly and simultaneously turn the adjustable capacitor C9 TX to see a perfectly synchronous flashing LED DL1 TX and RX. This confirms the correct reception of the signal by the RX. - Place the modules to about 1 m from the device to control (eg STB), taking care to put the RX in front of the camera so that the beam of infrared ray reaches well this unit.
- Operate the remote control again and make sure the unit is ordered (for example, that the decoder will light).
Experiment with several buttons on the remote and verify that whenever the corresponding command has been received by the device. Otherwise, edit R16.
- Let the ray where it is and éloignezvous gradually with the remote and the TX, while continuing to monitor the proper functioning of the system.
- Finally, set the carrier frequency of the RX module, and for that, put yourself in a more critical position, as shown in Figure 18: misalign slightly the RX and the controlled unit. - Bring the module TX and RX module operate the remote. Verify that the command continues to be received by the device. If this is not the case, edit R16 to the improvement of the action on the device commandé.Quand all this is done, return the RX front of the camera to operate.
Figure 17: Installation in their respective plastic housing of the transmitter module TX (the smallest) and the receiver module RX, each powered by a 9 V battery 6F22
Figure 18: To set the carrier frequency of the receiver module, you need to slightly misalign the module from the device to be controlled (eg by a decoder) then set trimmer R16 to obtain, even in this critical condition, a correct order of the device.
Conclusion If you want to also operate other devices like a DVD player or VCR, you stack them as shown in Figures 2 and 4. Put the RX well in front of this stack to easily reach the IR beam devices. 
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