Video Sequencer

[CeaSaR]

Hi everyone.<p>I would like to set up a small video surveillance system with several cameras from Alltronics and a standard VCR (the time periods under question are short and specific, so long running vcr's are not a necessity). I would like to be able to run the cameras through a sequencer prior to recording, but I don't want to buy a commercial/ready made sequencer as the prices are kinda steep. I figured a 555 based timer (variable 1-3 seconds) running a 4017 decade counter would work, but I wasn't sure if I should just use a transistor for the switch (3904?) or if I should use something like a reed relay? The 3904's would be more cost effective if they can be used for video. I also want to put an LED on the output to the transistor for an indicator light if possible and tie outputs 1 through 9 back to reset through a 10 position switch to select the number of inputs to sequence. Anyone have any ideas/thoughts/help?<p>Thanks,
CeaSaR

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Consider using a 4066 CMOS bilateral switch.

[Ron H]

Unless you have your cameras genlocked (not likely with cheap cameras), your VCR will have to relock with each transition, which probably won't be a problem, but it won't be pretty.
4066's may have unacceptable crosstalk, especially if you have color cameras. You can arrange each input of the multiplexer as series-shunt-series, which will solve the crosstalk problem (if indeed you have one), but it requires 3 times as many parts. Maxim and other mfrs make video multiplexers and crosspoint switches. Go to this site and do a search for "video multiplexer" and "crosspoint". Maxim is supposedly generous with samples.
You could make a multiplexer from bipolar transistors, but a reasonably good one requires 3 transistors per input. I can show you how to do this if you're interested. Up until about 7 years ago, I designed video routing switchers for a living.

[Kerry]

Hi,<p>Follow this link for a simple 4 channel switcher project that appeared in Electrnics now a few years back..<p>http://www.glolab.com/freeinfo/videosw.pdf<p>Kerry

[Kerry]

Hi,<p>Follow this link for a simple 4 channel switcher project that appeared in Electrnics now a few years back..<p>http://www.glolab.com/freeinfo/videosw.pdf<p>Kerry

[CeaSaR]

Deac_1,<p>Thanks for the link. I actually have this copy "somewhere" around the house. Originally bought it for the Noise-Cancelling Headphones in hopes to adapt it in the fight against those who sit at the nearby traffic light with stereos a-thumpin' and rattling my windows (not Microsoft).
I'll have to dig that out after the holidays...<p>RonH,<p>Is there a way to hold the genlock for these cameras by making them ground mostly to black (saw in a recent NV q&a column) and reducing the signal to a low level (yet still high enough to hold lock) and when it switches in, the "genlock circuit" is bypassed giving full signal to the bus? IE, signal goes to common point of NPN/PNP feedthrough, NPN is straight through while PNP goes to common point of resistor pair, one going to ground and the other going to bus at output of NPN/bus (GND res. is fade to black, other is signal reduction). Would this work or am I barking up the wrong tree?<p>The first mentioned circuit is great, but I want more flexability, with the added satisfaction that it is a circuit that is "mostly" homebrew, although ideas and references are ALWAYS welcome!<p>Thanks.
CeaSaR