In SX Microcontrollers, SX/B Compiler and SX-Key Tool, Mayfield wrote:

Bean is correct about the DG535, I've used these with nice results.
If you want to use Relays and need high isolation between sources, you might want to take a look at the PDF file that Bean referenced, on page 5-10, Fig-12.

 


[url=http://www.vishay.com/docs/70070/70070.pdf][u]http://www.vishay.com/docs/70070/70070.pdf[/u][/url]

 

This shows the switching arraignment of the "T" Switch, and can be implemented using Relays or CMOS switches.

The "T" Switch provides a high degree of isolation.

That third switch to ground, helps short out any crosstalk between the input and output switches when they are open.

Even though Video might be only a few Megahertz, the harmonics can be very high and love to jump across open contacts.

It's tempting to use all three contacts in a single relay, but, it is probably best to use a second Relay for either the input or output switch.

Also... use Break before Make if possible.

Watch any Circuit-Board Layout, too.

 

Tom M.

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