Mods 1.2Ghz 700mw TX from DinoDirect

This transmitter from DinoDirect is of good quality,is declared as transmitter output power 700mW however delivers 850mW in channel 1 to 993 MHz,and  550mW in the channel F to 1280MHz, the design is pretty good, superior to those found on eBay.

The modification in progress is to make it to 20 channels in the ATV, that is from 1220MHz to 1306MHz keeping the same hardware, the microcontroller has no brand, however when connected to an I2C serial memory EEPROM 24C02

Reading unknown uController , the programmer is not recognized as a   PIC16F628 or PIC16F84, though recognized as PIC16C54 or PIC16C74,but not ID chip.

Interface ICSP to unknown uController

The EEPROM I2C 24C02 read from 16F628A as Memory Scanner,the stored data has no relation with the values N PLL chip (either 31.25 or 62.5 or 100KHz step), nor is related to the 7-segment LED display connected to portB,apparently only used to store the last selected channel, and at position 256 EEPROM I2C (last position)

 The uController is code protect enable,the programmer recognized as a   PIC16C84 or PIC16C54, ie, no EEPROM inside uC ,no ID chip, I extracted uC from board, is not possible to rewrite.
I can not seem to do anything for "flashing" this uC. It is Similar to "16C" familly Microchip
I think the only solution is to simply use a PIC with EEPROM inside like the 16F628A or 16F84A in smd package,I will wait until a PIC16F628A SMD.

For Mods the plan is as follows:

1) Use EEPROM 24C02 to store data N PLL,High byte and Low bytes,also the value to load into the PortB  to the Common Anode display 7 seg. ,so cheese can edit how many times you want the frequency in 23cm ATV band(1220-1306MHz)
2) Conect bus I2C to uController 16F628A or similar,same size and compatible pins out.

Partial schematic of uControler, appears PIC16f628  as a matter of simulation with Proteus

this is the I2C EEPROM 24C02 re-written, 20 values each



 Finally got my hands on a microcontroller PIC surface mount, but the first tests were very bad,the small 7-segment LED display could not resist my hot air gun does not work, there are some unlit segments this delayed my project, I decided to use one of my controllers with LCD display to control this Tx

4MHz crystal is used not only for the original controller, but it also is injected into the PLL TSA5520, so I've disconnected the small coupling capacitor in place and a 4MHz crystal and a 18pF capacitor in series

FPV Receiver type: THE "DON'T TOUCH THIS"

I bought a 1.2GHz cheap receiver of those who do not have microcontroller inside, just a knob to tune,expected to find the pll chip inside, Not so, the PLL chip was missing.

Watching the tuner module can be concluded that the type PLL was SP5055, thanks to an old rusty tuner could be drawn from it a SP5054 chip, very similar in its functions and pins to SP5055.

Knob is a 10K variable resistor,volts tune only  0 to 5V DC

The tuner module  has a small plate with a FM demodulator chip implanted.

Purely analog base-band no microcontroller, no video amplifier chip(NE592),only transistor type smd, chip for subcarrier audio demodulator type MC3361 of Motorola.

No coil for FM sound demodulator, only 5.5MHz ceramic filter

This photo shows the implanted SP5054, replacing the original chip SP5055

The micro controller type 12F629, input port is a RC IR sensor  for Sony protocol,for example if press keys: "1","2","9" and "6",the receiver frecuency is 1296MHz, other example: "0","9","2" and "8",the receiver frecuency is 928MHz

The TFMS5400 IR sensor module is large and cheap on Ebay

Ready...





Universal Remote Control (from my Cable Magic TV) as Keypad for set frecuency of this cheap and Mod FPV Receiver

if set frecuency out range of PLL, then blink led 20 times try locked(re-send serial bits),automatic enter a new setting and LED continuos.

modifying the transmitter

This 4-channel A/V transmitter is declared 700mW, however only 280 mW gives on Channel 4  (1200MHz),is very popular in  FPV, looks very nice, smooth finish unlike the other on eBay.
My idea is to control the widest possible range of frequencies

BLT81 Transitor it is final stage,probably this can give 500mW at 900MHz as transmitter of DPCAV , adjusting the variable capacitor could get 350 mW on 1200 MHz

My idea is to modify the transmitter with the least possible damage

With a soldering iron and some skill is possible to separate the case components of the transmitter to access the controller chip.
I was very surprised that this transmitter is of Racewood

The microcontroller has no part number, perhaps a PIC12C508 as I saw a photo posted (RCGROUPS) a Racewood Tx

Here microntroller and Dip SW remove out, pin out to PLL TSA5520, the microcontroler check always PLL locked,if PLL unlocked, send  serial bits again. My control program aims to do the same, but expanding the range of frequencies to synthesize.

This graph shows the frequency versus the voltage on the varicap diode, the lowest frequency of 1040 MHz the PLL takes a while to locked, in the frequency of 1270 mhz never locked.

Changing the value of the inductance (L printed) of the oscillating circuit of the VCO is possible to synthesize more frequencies up or down.

Like most of these transmitters use the PLL TSA5520,control program should be able to handle frequencies from 900 MHz to 1300 MHz.

You must remove the pull-up 10K(103 marking) resistor on GPIO.4 (pin 3)

Frecuency Programing by IR Port  and Sony TV Remote control

The TFMS5400 device is a IR sensor module, this module is very large and not within the container the transmitter, the solution is to mount it outside and secure with hot glue

you just have to remove the original microcontroller  and replaces with PIC12F629, remove the resistor 10k smd  and connect the module sensor IR


The hex file for PIC12F629 here , Caution !!! it is only for PLL TSA5520.
To start the LED one blink when sending data, you have a minute to adjust the frequency.
The LED will remain lit when you press the "OK" button on the TV remote control Sony, indicating ready for adjustment. If press "OK" again then exit adjust mode (LED off).
Pressing the 4 digits of the desired frequency, the LED flashes between digit and digit, Wait until the LED is on for the next digit press.
If you want to 1280 MHz then push "1", "2", "8", "0" on TV remote control Sony.
If you want to 980 MHz then push "0", "9", "8", "0" on TV remote control Sony.

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Modify 1,2GHz A/V receiver for FPV

I bought this Kit Wireless 700mW from Securitycamera2000 , This kit is used for CCTV and also for FPV,although only 4 channels, my idea is to modify it to expand the frequency transmission and reception.
Original Channels:
1 1080MHZ
2 1120MHZ
3 1160MHZ
4 1200MHZ

I started to modify the circuit of the receiver,the main board contains the video amplifier, the audio demodulator and the microcontroller to control the PLL inside tuner module.

This module is as found in the old analog satellite receivers,the PLL is the TA1322FN chip, also contains down converter circuit is very similar in programming the SP5055,in my tuner the address selection pin is grounded.

Details pins for tuner module

Controller core is the PIC16F628A, a 16x2 display and 4 buttons for setting.

FEATURES
 900MHz to 1300MHz frequency
 Step 250KHz, 1MHz, 5MHz and 10MHz (Up Date 20/02/2012)
 Supports up to 8 pre-set frequencies
 Button lock mode
 Automatic shutdown of the display backlight after 10 seconds
 4 adjustment button:
 Button up: frequency up
 Button down: frequency down
 Step button: short touch = change step / touch along = locks
 Memory button: short touch=call preset channels/ long=records in memory / lock mode =unlocking three hits

Hex file and schematic  available  here 

Any questions or comments please do not hesitate to contact to the email josuezb81@gmail.com , I can also customize the text on the second line display and the frequency range.

Watch my FPV Receiver's video here http://www.youtube.com/watch?v=bwVUDE7nAi0&feature=mfu_in_order&list=UL



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Visit my blog about DATV in spanish.

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