X-Message-Number: 8267 From: (Randy) Subject: Member-down emergency alert system Date: Sun, 01 Jun 1997 03:24:52 GMT I have been thinking of developing a member down alert system, designed to alert by phone a cryo org in the event that a member has not moved in a certain amount of time. This would hopefully avoid long times of room temperature ischemia, thus allowing for better perfusion. I may have finally found what may be an appropriate infrared detector, an AMP (brand name) passive Infrared module (PIRM); operating voltage 5 v dc, 2.0 mA, spectral response of 4 to 20 micrometers -- what's the freq, and does it matter? Digital output; normally low (+0.7 v max); Active high ( +3.8v min); Analog; Offset @ 2.5 V. Anyone have any ideas on the meaning/relevance of the preceding info, which comes from the spec sheet? I have hooked up this detector to a 5 V dc regulated powers supply (no voltage divider; it's right across it). The steady-state (no movement) output is ~2.18 V dc. Immediately after movement is sensed, voltage quickly drops to zero and then reverses polarity and maxes out at about -2.2 v dc and quickly reverts once again to 2.18 v if no further movement is sensed. This transient occurs in about a 2 second time frame( or less). The range of this detector is about (insofar as I have determined) about 10-12 feet. The detector detects motion through about 75 degrees on the horizontal axis. However, the vertical axis is not nearly so good, with a detection range of perhaps 30 degrees at 5 feet. What I need help on is design of the circuit fed by the detector. I was thinking perhaps a diode (zener?) which is biased into conduction by the transient spike of opposite polarity voltage generated by detected motion. The diode, during a brief conduction period, could short to ground a resistive-capacitive circuit hooked up to the power supply. The time constant of this RC circuit would be such that if it is allowed to charge for, say, one hour (without being discharged by zener), would then build up to a voltage level sufficient to bias into conduction a solid state relay. On the other side of the solid state relay output would be the phone and time delay circuits. I have a phone with 3 memory circuits. I have accessed the memory button wiring and can short around these buttons and the on-off switch. The plan would be that, once the RC circuit has fully charged (no motion after one hour), the relay would close, closing the on-off switch (taking the phone off the hook, effectively), a time delay would then kick in, perhaps a couple of seconds to allow for a dial tone, then another relay would close, shorting out memory button one, which would dial a pager number for one of the cryo org standby team.=20 The other time delay circuit would run a couple of seconds longer, and then close another solid state relay contact, which would short memory button 2, dialing the phone number for the cryo member's own phone, which is then stored in the memory of the pager belonging to that standby team member.=20 Of course, everything on the phone side of the relay is another problem entirely, and can wait until the detection circuit is complete. I realize that this is a very modest attempt at a cryo alert system, but we must start somewhere. This could begin with a one-detector system set up by the bed of a cryo member with heart problems. It would not be perfect, and could be reset manually by the member after a false alarm, thereby simplifying the circuitry. An alarm circuit would need to be included--more amps! So if anyone has any ideas on the circuitry on the detector side of the solid state relay, I would appreciate it. Speaking of which, those solid state relays aren't cheap, so I'll probably try to build some from _Electronics_Now_ magazine schematics. (The detector itself is only $8). Also, any ideas about testing this thing? I have a Fluke digital multimeter with max, min, range, and delta functions. I have placed the detector about 2 feet from my bed, and it does detect motion when roll slightly, e.g., from laying on my right side, to my back. This power supply I have has a single output, variable from 3 to 12 vdc, capable of 2 amps. Of course if different voltage levels are needed, and of course, they will be, we need to devise voltage dividers. I have spare fuses, of course. :-) This alert system would be available to all cryo orgs. As of now, no one has one, AFAIK, and it not only could save lives--if cryonics works, etc--but also could improve quality of suspensions, helping to bring in new members( if suspension reports are available). A workable, cheap alert system would also say something about the seriousness of cryonics. Randy =20 Cryonics: Gateway to the Future? http://members.wbs.net/homepages/c/r/y/cryofan1.html =20 *********************************** Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=8267