But when we talk about differential sensor, we mean 3 wires, right? I mean, not only the two complementary signals, but a ground MUST be there, else it won't be a differential sensor.. am I right? Cheers, Mario At 17.02 2012.02.09, you wrote: >I would consider using a decent-quality audio transformer for=20 >isolation into your circuit. That means that you can use a normal=20 >single-ended (not differential) amplifier for signal conditioning. > >The transformers that I use are a semi-custom part (standard part=20 >number but manufactured when the order is placed) that I purchase in=20 >thousands. They are relatively small (similar in size to Mouser's=20 >TM016) but with super high inductance and darned decent low-frequency=20 >response. Provided that your amplifier has relatively high input=20 >impedance, the truck's sensor and electronics should not even notice=20 >the addition of your circuit. > >I'd be happy to send you a couple of transformers for you to try and=20 >I can supply as many as you need, up to the point where your=20 >quantities justify you ordering them yourself. > >Something like Mouser's TM016 is most likely NOT suitable because the=20 >inductance is fairly low - the low frequency response of those=20 >transformers is rated at 200Hz when fed with a 600R source. They are=20 >OK for telco-type circuits but not for Hi-Fi audio and certainly not=20 >for a variable-reluctance sensor where the speed approaches zero. > >dwayne > > >At 12:29 PM 2/8/2012, Bob Blick wrote: >>I need to design a device that interfaces to the speed sensor of heavy >>trucks. These are variable reluctance sensors and will remain connected >>to the vehicle's ECU, my circuit will piggyback. These are two-wire, >>differential signals full of common-mode noise and vary in amplitude >>greatly with frequency and also position as the tailshaft bearing wears >>in the vehicle. > > >--=20 >Dwayne Reid >Trinity Electronics Systems Ltd Edmonton, AB, CANADA >(780) 489-3199 voice (780) 487-6397 fax >www.trinity-electronics.com >Custom Electronics Design and Manufacturing > >--=20 >http://www.piclist.com PIC/SX FAQ & list archive >View/change your membership options at >http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .