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gicapa
Joined: 12 Apr 2001
Posts: 109
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 26 Jan 2003 9:55 video pattern generator |
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Video Pattern Generator with PIC16F84 and MC1377
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Borber
Joined: 01 Jan 1970
Posts: 1561
Helped: 117
Location: Slovenia
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03 Feb 2003 9:29 video pattern generator circuit |
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| This TV Pattern Generator has failures in sync timing. It does not comply to PAL standard (jitter on fields). But on most TV receivers it does not make problems.
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TurboPC
Joined: 14 Mar 2002
Posts: 151
Helped: 1
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05 Feb 2003 4:53 pal generator |
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| Borber wrote: |
| This TV Pattern Generator has failures in sync timing. It does not comply to PAL standard (jitter on fields). But on most TV receivers it does not make problems. |
It seems to be a circuit to generate PAL-N signal. PAL-N (mainly used in Argentina) has an NTSC-like subcarrier frequency. Used on a normal PAL tv or monitor, there will be no color at all. Changing the subcarrier frequency will effectively solve the problem.
The PAL-N and PAL-BGHI may have slight difference in the sync length, burst position and start/end of video, but there are large tolerances which will effectively make no difference at all on any tv/monitor.
Just make sure the burst frequency is set according to your tv -> otherwise, no color!
My two cents...
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Borber
Joined: 01 Jan 1970
Posts: 1561
Helped: 117
Location: Slovenia
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05 Feb 2003 6:48 mc1377 |
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Dear TurboPc
it seems that you havent understood what is the problem. It is not the colour subcarrier but sync timing. That is something absolutelly different.
As I can analyse the signal something is wrong in second field timing.
Instrument like WM700 simply reports Sync is missing.
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TurboPC
Joined: 14 Mar 2002
Posts: 151
Helped: 1
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06 Feb 2003 3:33 ad725 circuit |
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Sorry Border,
I did not know you tried the circuit. I just looked at the documents and everything was looking OK. My comments were only to pinpoint the differences between PAL-N and PAL-BGHI.
BTW, do you have the fix in gicapa's code? Is the missing sync pulse in the serration, half lines or other lines?
Thanks for the info.
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Google
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06 Feb 2003 3:33 Ads |
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Borber
Joined: 01 Jan 1970
Posts: 1561
Helped: 117
Location: Slovenia
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06 Feb 2003 6:13 mc1377 pic |
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Hi TurboPC
I just could'nt find out what is vrong. When signal is connected to Tektronix Monitor it shows jittering in the top 20% of picture. When looking at the vertical sync pulses they jiter regarding the field. Some jitter is present in line synchronisation but less then in vertical interval. It seems that pll in horizontal synchronisation of monitor is reducing it a bit.
I do not have suitable oscilloscope to be able to examine problem in details.
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pico
Joined: 30 Sep 2001
Posts: 285
Helped: 6
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07 Feb 2003 5:17 tektronix wm700 |
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What IC can replace MC1377.
Please help.
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Borber
Joined: 01 Jan 1970
Posts: 1561
Helped: 117
Location: Slovenia
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07 Feb 2003 6:09 mc1377 generator |
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| I used AD724 from Analog. They send samples.
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Kripton2035
Joined: 19 Jul 2001
Posts: 587
Helped: 20
Location: Earth
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07 Feb 2003 8:48 video pattern generator schematics |
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| you also have ad723 and ad725 from the same analog...
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shahzadismail
Joined: 28 Nov 2003
Posts: 2
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29 Nov 2003 6:13 pattern generater with pic |
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| gicapa wrote: |
| Video Pattern Generator with PIC16F84 and MC1377 |
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mbyka
Joined: 12 May 2002
Posts: 509
Helped: 1
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29 Nov 2003 10:22 crosshatch pattern generator |
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http://www.lpilsley.uklinux.net/temp/
same books
You can download
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kiks
Joined: 01 Jun 2004
Posts: 28
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14 Jun 2004 15:20 video generator pic16f84 |
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Here is another circuit for a simple dot cross hatch pattern generator. I got it off the net sometime ago. I do not have the link. I hope someone will find it useful.
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harleybg
Joined: 13 Aug 2006
Posts: 1
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13 Aug 2006 22:40 circuit video pattern generator |
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I have a problem with the 1st PAL generator(pic16f84&MC1377). There is a burst in the output signal, but the picture is in black and white. There is no oscillation on the crystal 4.43MHz. I tried to adjust the capacitator trimer, but no result 
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parth
Joined: 16 Mar 2007
Posts: 4
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16 Mar 2007 8:40 pal video pattern generator pic |
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i have rgb signals and sync pulses
can you help me by giving circuit of encoding the signals by using ad725
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Borber
Joined: 01 Jan 1970
Posts: 1561
Helped: 117
Location: Slovenia
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16 Mar 2007 9:44 ad725 circuit pal |
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| All you need is in it's datasheed.
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parth
Joined: 16 Mar 2007
Posts: 4
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31 Mar 2007 3:51 ad723 ad725 difference |
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i am using ad725. i am not able to find osci. of 17.73445Mhz.can anybody give me idea?
and if i do not use crystal will it give signal which can be used for black and white tv?
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Borber
Joined: 01 Jan 1970
Posts: 1561
Helped: 117
Location: Slovenia
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31 Mar 2007 5:15 pal generator mhz |
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Regarding subcarrier crystal you may use one of two other crystals (4.43361MHz and 8.86723MHz) together with frequency quadrupled or doubler. They are used in TV sets and probably you will find them.
Using ordinary LC oscillator instead of crystal will be satisfactory for B/W but not for colour signal.
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tonybg
Joined: 17 Mar 2007
Posts: 18
Helped: 2
Location: bulgaria
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31 Mar 2007 15:20 video pattern generators |
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Hi, I've built it, with MC1377,4.43361MHz quartz,added video modulator from old video.R15 at the emmiter of the output is 75 oms.Here is another pattern generator.I've used the pic part from it together with MC1377.It has more options.
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parth
Joined: 16 Mar 2007
Posts: 4
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17 Apr 2007 19:00 tv pattern generator schematic |
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have used AD725 instead of MC1377.
AD725 gives output 2V peak-peak at 75 ohm output impedance. I want it to convert it into the 1V p-p at 75 ohm output impedance.
can u help me?
I do now want to use only 5V supply
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Borber
Joined: 01 Jan 1970
Posts: 1561
Helped: 117
Location: Slovenia
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17 Apr 2007 19:40 ad725 16 bit color |
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| OK. Video level must be always measured on output terminated with 75Ω and not without load. 2Vpp is normal for unterminated output.
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parth
Joined: 16 Mar 2007
Posts: 4
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18 Apr 2007 8:48 ad725 project |
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| Can anyone give me the project Report of this video pattern generator?
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Anilsharma
Joined: 18 Mar 2008
Posts: 1
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18 Mar 2008 12:11 crosshatch generator circuit |
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I am looking for horizontal and vertical line pattern generator and also target ring with cross pattern genarator for mono monitor. Please suggest.
Regards,
Anil Sharma
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Tricksteeer
Joined: 30 Oct 2009
Posts: 1
Location: Romania
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03 Nov 2009 19:43 Re: Video Pattern Generator |
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| I built it but it generates only 2 patterns and only one colour (depending on the trimmer). On osci I get some spykes on the subcaryer. Can anyone help me?
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betwixt
Joined: 04 Jul 2009
Posts: 393
Helped: 64
Location: Wales, UK
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03 Nov 2009 23:57 Re: Video Pattern Generator |
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look on www.atv-projects.com
The PAL generator there will produce almost any pattern you program into it.
Brian.
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