Hedghog PSC is a homebrew programmable standards converter. From a 625 line input is capable of generating a wide range of Television line standards. It is coupled with a versatile programmable modulator that uses two MC44BS373.

On this page you will find the files required to build it.

 All material including Downloads on these pages are provided 'as is' without warranty of any kind, either expressed or implied.



    The converter can generate the following

    • Field frequencies of 25, 30, 50 and 60 Hz
    • Number of lines between 16 and 830
    • Number of active lines(lines with picture information) between 8 and 800
    • Adjustable length of front porch, line sync, back porch and broad pulse.
    • Number of broad pulses between 1 and 50.
    • Sync height of 20, 25, 30, 35, 40, 45 and 50%
    • Independent left and right crop
    • Selectable equalising pulses
    • Test patterns: Test card, Grey scale, Crosshatch, Cruciform, Black screen, White screen



    • Frequency coverage 28.5 to 900 MHz in 5 ranges
    • Frequency ranges and step:

        28.5   to 56.25 MHz  step 15.625 KHz

        56.25 to 112.5 MHz  step  31.250 KHz

        112.5 to 225 MHz     step  62.500 KHz

        225    to 450 MHz     step  125 KHz

        450    to 900 MHz     step  250 KHz

    • Selectable negative video FM sound or positive video AM sound
    • Selectable vision/sound carrier separation of 4.5, 5.5, 6.0 and 6.5 MHz  or when in positive video AM sound mode the video and sound carriers can be set independently(Variable mode)
    • Selectable picture/sound carrier ratio of 12 and 16 dB  or fixed at 6dB when in Variable mode
    • Can be used as a stand alone modulator


    All Resistors, Capacitors and Inductors are 0805 size.

    All Capacitors are ceramic multilayer types.

    Where given manufacturers part numbers are given as examples alternative parts may also suit.

    The PCB is double sided and measures 100 mm X 89.5 mm.

    Link to uploaded Gerber files on PCBWay.


    July 2021 I have updated the FPGA and PIC programming files.

    The update allows the converter to convert from 525 lines as well as 625 lines. It automatically detects the input standard. Also included in the update are some test patterns. The patterns are applied before the converter so are available on all output standards.



    Menu description (.pdf)

    Circuit diagram (.pdf)

    Component list (.pdf)

    Component layout top (.jpg)

    Component layout bottom (.jpg)

    Front and rear panel legends (.pdf)

    FPGA program file (.jic)

    Microcontroller program file (.hex)






Hedghog II PCB top

Hedghog II PCB bottom