If your requirement is really 'no external power supply', rather than 'no source of outside power', then a resistive sensor will work fine (something as simple as a spring and potentiometer, for example). Bob Ammerman RAm Systems (contract development of high performance, high function, low-level software) ----- Original Message ----- From: "Robert A. LaBudde" To: Sent: Monday, June 25, 2001 12:31 AM Subject: Re: [EE] impact sensor /pressure to volatge converter > At 09:48 PM 6/24/01 -0400, you wrote: > >You should be unable to find any sensor in this physical universe which > >will produce a voltage with unchanging prolonged pressure. If you found > >one, then I would take a few million of them, build my house on top and > >power the house with this 'infinite' power supply. > > If you give up on the self-powered part, load cells work nicely. > > If the force has a time element, either a piezo-electric sensor or a > geophone-type sensor (motion of metal within magnetic field, etc.) can be > used. Both could be made to generate a voltage waveform from an impact or > oscillatory force. > > > ================================================================ > Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: ral@lcfltd.com > Least Cost Formulations, Ltd. URL: http://lcfltd.com/ > 824 Timberlake Drive Tel: 757-467-0954 > Virginia Beach, VA 23464-3239 Fax: 757-467-2947 > > "Vere scire est per causas scire" > ================================================================ > > -- > http://www.piclist.com hint: To leave the PICList > mailto:piclist-unsubscribe-request@mitvma.mit.edu > > -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu