Saturday, June 13, 2015

PLL Synthesized FM Receiver Circuit with LCD - 16F88 LM7001

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FM Tuner
FM Tuner

This is high quality stereo digital PLL synthesized FM radio receiver circuit that can scan with 76 MHz and 108 MHz seamlessly between 100 kHz step, although the sensitivity is high.

Main components of this receiver are a PIC16F88 micro-controller, 16x2 LCD, LM7001 PLL Frequency Synthesizer, AN7223 IF Amp, TA7343 MPX and a FM Tuner. This system is design to work with 12V DC power supply and the LM7805 and 7808 regulators used to manage power requirements to the above-mentioned components.

User interface of this system consist with 6 push buttons and a 16×2 character LCD module. All the functions of this receiver can control by this buttons and necessary information displayed on the LCD.

Specifications of this receiver

  • High sensitivity
  • Standby mode
  • Preset memory stations up to 250 (default 20)
  • 3-user selectable frequency ranges (default 87.5-108)

Schematic of PLL and Power circuit
Schematic of PLL and Power circuit

Schematic of micro-controller and user interrface
Schematic of micro-controller and user interrface

LM7001

The LM7001 is a PLL frequency synthesizer LSIs for tuners, making it possible to make up high performance AM/FM tuners easily. These LSIs are software compatible with the LM7000, but do not include an IF calculation circuit. The FM VCO circuit includes a high-speed programmable divider that can divide directly seven reference frequencies. Serial input circuit for data input (using the CE, CL, and DATA pins)

Tuner 

Anticipating the objection that these tuners do not find, I assure you that if you do not be lazy and go through the repair shops where repair radio. In addition, you can get this tuner from old audio system and car set. There are 3 types.

Types of tuner
Types of tuner

  1. FM Front End only (you need to build IF Amp, MPX circuit)
  2. FM Front End with IF (you need to build MPX)
  3. FM Front End IF and MPX

IF Amp and MPX

For IF amp I used AN7223 because it need few external parts and it has high sensitivity and stability. If you cannot find FM quad coil then you can use 2pin 10.7MHZ ceramic resonator for that (see datasheet for more details). However, it is possible to use another IC for this as AN7220, TA7640 and KA2297 etc.

For MPX decoder here I used TA7343. This IC decode mono signal to stereo. This is an optional part. If you wish to work with mono, then omit this part and connect amplifier input with ‘AF’.

IF and MPX circuit
IF and MPX circuit

Complete circuit pcb
Complete circuit

Operation

Numbers of memory locations are determine by the value of Eeprom 1 (default value 0x14) and frequency range is determine by the value of Eeprom 2 (default value 0x00).
  • If value is 1 then range is 76-108MHz
  • If value is 2 then range is 76-90MHz
  • Else, range is 87.5-108 MHz

Selecting the station:
When we are in the power on mode, on the screen we can see "Frq:106.5 Ch:15" - tuned frequency of the station and then the number of the cell where the recorded frequency of the station. Pressing ‘CH_UP’ and ‘CH_DN’ we can move the recorded stations. Pressing ‘FR_UP’ and ‘FR_DN’ we can change the frequency. ‘STORE’ stored the current frequency to the current station and ‘PWR’ used to toggle standby mode and power on mode

Micro-controller runs using its internal oscillator. RA6 pin can directly connect with background light of LCD display. As well as it is also can used for the controlling another device like mute pin of power amp. For VCC (tuning voltage) you can use up-to 12v.

Firmware of this system was written by using MikroC for PIC and schematic, hex and Proteus files are available for download.

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  1. Very nice effort,,,,, I was searching for such LM7001 Frequency Synthesizer based FM radio (by using the tape recorder module....)
    can i get its PIC Micro-controller mikroc source code??
    Thanks

    ReplyDelete
    Replies
    1. Send your email address and I will send you a demo code.

      Delete
    2. My Email:
      kamranmu@yahoo.com

      Thanks

      Delete
  2. I want to try this part, can you send me source code? For more learn about microcontroller. My e-mail taupiksuwoko@gmail.com

    ReplyDelete
  3. Hi.
    thank you very much
    can you send source code for change.
    my email is sss.zare@gmail.com

    ReplyDelete
  4. This comment has been removed by the author.

    ReplyDelete
    Replies
    1. First of all you need to store desired frequency to device. To do this first Press fr_u button. you can see 87.5 on display. Then use fr_u/d buttons to set frequency and store button to save.

      Delete
  5. Please sent email afixnet12@gmail.com using chip atmega8. thank you

    ReplyDelete
    Replies
    1. I've tried it with pic ic 16F88 but the programming process to ic pic hex file can not be found in program(error write).please hex code that can send email to me afixnet@gmail.com

      Delete
    2. The hex file is correct. however I'll send you a hex file

      Delete
    3. ic 16F88 for what should be the setting of fuse bits first? or to the factory settings

      Delete
    4. Do not modify fuse bits. It will be automatically set when you load the hex file

      Delete
    5. how to change the frequency to 76-108 mhz? .i have tried it successfully but freqwensi still in 87-108mhz. whether to buy the premium hex file if yes how? I am from the country Indonesia

      Delete
    6. Change eeprom address 0x02 value to 1 (default 00)

      Delete
    7. This comment has been removed by the author.

      Delete
  6. Can u help me with source code of this project f.m receiver
    My email ikramhussein2013@gmail.com

    ReplyDelete
  7. Pls can help me with source code of this mikroc I can download from here
    My ikramhussein2013@gmail.com

    ReplyDelete

 

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