There are a couple of factors that affect this. First, the ON resistance of most (inexpensive) analog switches is quite high (hundreds of ohms). The pricier units get that value down, but still don't want to pass a lot of current. Second, the cheaper ones (4061, 4066 etc) require control voltages in the range of the signals to be switched. Want to switch a signal that swings to +10V? You need 10V logic, and a 10V supply rail. Maxim (and others, I'm sure) make some that have dual supplies, one for analog and one for digital, but those get pricey. Your best bet is solid state relays. Jameco (for example) has some in the $2-$3 dollar range. MUCH better than most of the analog switch chips. Mike H. >The analog switches that I have recently found, opened a new window for me. >Could I use the analog switches, like MAX323, like a relay? To better >explain what I am thinking, if I have circuit that works with 3V, could I >use the switch to close and open a 24V line coming from outside world, thus >imititating the SPST relay? > >Thanks in advance, > >Omer _________________________________________________________________ Test your Travel Quotient and get the chance to win your dream trip! http://travel.msn.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.