Dear Chris Eddy and Sam Woolf, Chris Eddy on 2001-05-25 07:57:40 AM talked about impedance matching, then said > On the pulse generate end, you want to drive the > signal through a 50 ohm resistor into the center conductor. I don't think so. If I have a signal generator, a long wire, and a transducer at the other end, adding a resistor in series with the wire *decreases* the energy that makes it to that transducer. Isn't that exactly the opposite of what Sam Woolf asked for ? Impedance matching is the solution to some *other* problem. sam woolf on 2001-05-25 07:19:41 AM wrote: > I'm sending a pulse from a p16f84 down a fairly long wire to some ultrasoonic transducer circuitry. > By the time it gets there the voltage has dropped significantly. Whats the best way to overcome this problem? do I need to build some kind of booster circuit? Sorry if this is a overly simplistic question- I'm an electronics newbie.. > Sam,. Are you saying that the transducer circuit works fine when directly attached to the PIC, but isn't loud enough once you insert that long wire between them ? Lots of different options. The ``best'' one depends heavily on what exactly is on the far end that you're trying to drive. (Is this a FAQ yet ?) - Same voltage, more current: inverters, or line drivers like TI TPS2828DBVT TI TPS2815 TC1412 (less than $1 at DigiKey)(each can drive 1 A into capacitive loads) , or a simple discrete transistor driver. (simplest) - Same power, more voltage: impedance matching using inductors; pulse transformers. - More voltage and more current: op amps; for maximum power people use discrete transistor driver + transformer. Is your ``transducer circuit'' a 6500 Sonar Module http://rdrop.com/~cary/html/ultrasonic.html ? If not, I'd be interested in learning more. -- David Cary -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body