VoyForums
[ Show ]
Support VoyForums
[ Shrink ]
VoyForums Announcement: Programming and providing support for this service has been a labor of love since 1997. We are one of the few services online who values our users' privacy, and have never sold your information. We have even fought hard to defend your privacy in legal cases; however, we've done it with almost no financial support -- paying out of pocket to continue providing the service. Due to the issues imposed on us by advertisers, we also stopped hosting most ads on the forums many years ago. We hope you appreciate our efforts.

Show your support by donating any amount. (Note: We are still technically a for-profit company, so your contribution is not tax-deductible.) PayPal Acct: Feedback:

Donate to VoyForums (PayPal):

[ Login ] [ Contact Forum Admin ] [ Main index ] [ Post a new message ] [ Search | Check update time | Archives: 1, 2, 3, 4, [5], 6, 7, 8, 9, 10 ]

[ Next Thread | Previous Thread | Next Message | Previous Message ]

Date Posted: 17:47:51 01/27/03 Mon
Author: Pokey
Subject: Re: New ideas & intermittent audio
In reply to: Jain 's message, "Re: New ideas & intermittent audio" on 12:05:13 01/27/03 Mon

>Hey Pokey
>I finaly found your message... First, you are using
>the right code. As Potter said, the circuit is quite
>sensitive to oscillator setting, so you may wish to
>try a different cap or other solutions (parallel or
>serial caps) to fine-tune it.

I used two var-caps (5-20pf) in series with a 10pf cap in parallel with the var-caps. This gives me a 12.5pf to 20pf swing. I was able to lock onto ch75 (showed a fixed viewer's choice logo) but the picture was vertically offset by about half the screen.

>Forget about locking on normal channels, it's not a
>datum.

Okay, it seemed impossible anyways ;).

>Last, remember that the video is inverted, you must
>enable only the section of 4066 that lets the
>inverting video to pass to the output.

switched it, thanks.

>The input level has it's importance, so I would say
>that, without a scope that synchronizes very well on
>TV signal (vertical synchro pulse), preferably a
>digital one, it's not easy to adjust this baby, unless
>it works fine right from the first start.
>Jain

To get ch75 to lock I had to adjust the video gain a bit to stop it from unlocking. I also adjusted the clamp level and saw that the picture faided to black or white depending on how much I went in either direction on the pot. But I didn't see much change when I adjusted the output gain or burst gain.

After getting ch75 to lock I tried other channels and I didn't get the circuit to lock.

Pokey

[ Next Thread | Previous Thread | Next Message | Previous Message ]
[ Contact Forum Admin ]

Forum timezone: GMT-8
VF Version: 3.00b, ConfDB:
Before posting please read our privacy policy.
VoyForums(tm) is a Free Service from Voyager Info-Systems.
Copyright © 1998-2019 Voyager Info-Systems. All Rights Reserved.