Just wanted to add that I am faced with a similar issue with one of those old rj 11 systems. This is my first attempt at cctv, and though I managed to convince the boss to upgrade his 4 channel system circa the 90's, he wanted to use the old cameras instead of buying new ones. Mind you this is after we just got robbed and had zero video evidence as the old system doesn't even record. Also, he also plans on buying a 32" lcd to display the camera feeds to customers to dissuade theft, but the old cameras are like 240 tvl and I'm guessing will look terrible on a screen that big. Anyway, he bought an 8 channel HD dvr under my advice. I had hoped everything would mesh, but then of course discovered that the old cameras use rj 11. Researched it a little and, as someone noted above, learned that the old cameras are powered directly by the Samsung CCTV monitor. I was basically screwed and boxed my boss into having to spend more, but then I noticed that there were 4 BNC outputs in the back of the old monitor. I connected each of these to the new DVR and sure enough, they all showed up on the new unit. The solution was simply to piggyback the new DVR off the old. And now that he's seen how terrible the old cameras look connected to a brand new unit, I was able to convince him to supplement the 4 old cameras with 2 HD cameras. I found an 8 channel power box for $40, cameras for $50 each, and some cheap Siamese wiring. Incidentally, the boss has a triple play package for our company internet and phone, but has been paying for cable and not using it for over three years. I was able to connect the cable box to the old Samsung, and now it functions as both a power source and throughput for the 4 old cameras and a television for our breaks, simultaneously. The new DVR records all 6 channels. Once the 32" LCD arrives, I plan on displaying the two HD camera images larger than the other 4 , which will hopefully give the allusion that all 6 cameras are of similar quality. Anyway, that's one option if you hadn't already surmised.
