toddi@yang.cpac.washington.edu (Todd Inch) (12/01/89)
In-Reply-To: volume 9, issue 526, message 4 of 8 In article <telecom-v09i0526m04@vector.dallas.tx.us> KLH@nic.ddn.mil (Ken Harrenstien) writes: >If any of the flasher devices used an all-purpose relay instead of an >resistive-only triac I could at least invent a Rube Goldberg >arrangement that repeatedly bashed at a controller button... :-) The simplest, cheapest way I've found to get a relay-type ring detector is to use the existing phone guts and ringer and replace the core of the ringer's electromagnet with a reed switch. Specifics: Use the network and ringer from any common, old-fashioned, non-electronic phone (e.g. 500 or 2500 series) with a mechanical bell. Unscrew the two screws which attach the electromagnet's core to the ringer frame. Slide the core (several layers of sheet iron about 1/4 inch wide and about 2 inches long) out of the electromagnet and re-secure it to the ringer frame so you can put it back together later if you want. Now you've got the electromagnet coil still wired to the phone set's network. Just insert a reed switch in the hole left by the removed core and you've got a controller-button-basher, or use it for whatever else you could connect to a relay. You could leave it inside an existing in-use phone set and connect the reed switch to the unused (yellow and black) phone cord pair. Some considerations: The phone cord can't handle the current of a table lamp if you want a Flasher, so use a heavier cable. If you do connect this to a digital wireless-type power controller (BTW, DAK has 'em on sale in the December catalog), you may need a shielded cable running to the reed switch and you may need to keep the cable short to avoid introducing noise into the controller circuits. You may even need to shield the switch inside the coil. Since the original electronics is unmodified, I would think that the FCC approval for the ringer (phone set) would still be valid, if anybody cares. Since the electromagnet has been physically modified, this might change the ringer equivalence a little, I suppose. The "reed switch": For those unfamiliar with this, it's a small, sealed glass tube with two iron "leaves" inside which (for a normally open switch) overlap but don't quite touch each other. Short wires stick out either end which you solder (sorry Ken) wires to. The iron leaves attract each other and act as closing switch contacts in the presence of a magnetic field. Where to get a reed switch: Radio Shack used to sell them in a pack of 5 or 10 assorted, but I don't see them in the new catalog. I'm sure someplace like Edmond Scientific has 'em. If you're in a hurry or lazy like me, RS has a couple of reed relays which could be taken apart to salvage the switch (pg 132 in 1990 catalog). Most burglar alarm door sensors (such as RS #49-495, 49-496, 49-503) also contain them. If the sensor is small enough (49-496?), it will fit in the coil as-is. Some of these (49-496) have wires attached and are insulated, so no soldering. Disclaimers: This info is just from my own personal phone phreking. I don't even like Radio Shack, but they're handy. Phone lines'll shock you good when they're ringing! Sorry about my verboseness. Todd Inch, System Manager, Global Technology, Mukilteo WA (206) 742-9111 UUCP: {smart-host}!gtisqr!toddi ARPA: gtisqr!toddi@beaver.cs.washington.edu "You are the booger in the nose of my life." - My wife, to me. (Jokingly?) Disclaimer: My boss will read this while checking up on me and will disagree.