gil@limbic.UUCP (Gil Kloepfer Jr.) (07/09/88)
Here's a synopsis of the latest responses I got concerning the interface to the UNIX-pc and how to prevent the TVI it causes: ************ The best thing to do is find out if you are really getting into you neighbors' TV's. If not, work with shielding to kill the splatter. If so: A) Isolate the A.C. supply to the system (extreme, yes.); B) Shield the cable with either a shielded cable (Ground 1 side only!), or enclose the device, cable and all, in an RF shielded box; and C) Only use the system during to early hours of the morning. Randall W. Robinson, rrobinson@ames.arc.nasa.gov ******** Try wrapping the entire cable in tin foil grounded on one end, and running many a ground wire in the cable itself. ie any unused leads. Works for me. Ron Fletcher, AT&T EUO, mtgzy!rlf ******** You might try using shielded ribbon cable. We use the stuff on some equipment where I work. It is normal ribbon cable encased in a carbon impregnated rubber jacket. John A. Limpert, johnl@n3dmc.UUCP, johnl@n3dmc.UU.NET, uunet!n3dmc!johnl ********* Maybe you ought to start a mailing list for us die hards? :-) Robert J. Granvin rjg@sialis.mn.org ********* What did I do? Ok, I went to my local retail hardware store and bought some of that alumnium duct tape and (longwise) covered the ribbon cable and power connector in it. The ground connection was to the chassis by means of putting the plate on the back so that the aluminum tape was forced against the chassis. This DID help a little, but I think that part of the problem may be in the electrical ground of my apartment. I haven't confirmed that it messes-up the folks here on cable (I decided I was not going to pay for cable, and put a roof TV antenna in the attic :-). I have a feeling they are ok. As for the idea of a mailing list -- I don't think we need one right now as posting to unix-pc.general should suffice. If I come-up with something new that isn't of interest to the rest of the unix-pc community, I will send email to those who mailed or posted responses. I will make the schematics available as soon as I have them (I am doing it in my "spare" time). It won't be something for the weak-stomached and will definitely require a good working knowledge of digital electronics for the construction and use. Tools are important... So far, I succeeded in locking-up the kernel several times by playing with interrupts. Be sure to have a recent backup of your system when you play with this stuff, and keep your floppy unix (the foundation set) handy so you can boot up from floppy and run fsck's stand-alone. I ran into an obscure problem where I had to do this, and it is always a handy thing to have around. If you can help it, try not to lock-up the kernel 8-(. My thanks again to Mike Ditto for posting that vidram driver. It was a 5 minute lesson in writing device drivers which saved me the headaches of sifting through the AT&T "Better-than-nothing" Documentation. +------------------------------------+----------------------------------------+ | Gil Kloepfer, Jr. | Net-Address: | | ICUS Software Systems | {boulder,talcott}!icus!limbic!gil | | P.O. Box 1 | Voice-net: (516) 968-6860 | | Islip Terrace, New York 11752 | Othernet: gil@limbic.UUCP | +------------------------------------+----------------------------------------+