Path: utzoo!attcan!uunet!cs.utexas.edu!mailrus!accuvax.nwu.edu!nucsrl!telecom-request From: gtisqr!toddi@nsr.bioeng.washington.edu (Todd Inch) Newsgroups: comp.dcom.telecom Subject: Re: FCC REN Numbers Message-ID: <8405@accuvax.nwu.edu> Date: 29 May 90 14:02:22 GMT Sender: news@accuvax.nwu.edu Reply-To: Todd Inch Organization: Global Tech Int'l Inc. Lines: 101 Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 10, Issue 396, Message 4 of 12 Note: I attempted to post the below on May 22 but must have fouled up. Since then, I've read numerous responses. Hopefully, this is a little less technical. Watts = Volts * Amps, so if Volts is constant, you can substitute "Amps" in my analogy below, if that is any help. Somebody mentioned the phone company should be supplying roughly 5 Watts of ring juice, so maybe my analogy was more technically correct that I had intended. :-) To clear up possible confusion about the effect of the on/off switch: On many phones, especially ones with mechanical bells, this will not effect the REN at all - it still draws just as much current. On some, it may draw a little less current and have a lower effective REN than the FCC sticker shows. On very few phones, this may disconnect the entire ringer circuit from the line and therefore change the REN to 0.0. On all phones with mechanical bells that I've seen, (insert non-expert disclaimer here) simply disconnecting the bell inside (with wire cutters, screwdriver, or a do-it-yourself switch) would have the effect of drawing no ringing current, thus 0.0 REN. My favorite method of adding a bell switch to a mechanical bell phone is to wire the bell to an unused line wire (black or yellow) and then add one of those cheap hanging-lamp style cord switches to the line cord. This avoids having to drill holes in the phone, etc. If you did this to all the phones in your house, you could turn on/off all the bells at the phone by your bed. (Write me for details, it's really to boring and elementary for most readers.) My original non-posted article: Stephen J. Friedl, a 3B2-kind-of-guy, asks about REN's and what good they are. I'm sure someone will correct me if I'm wrong, but I've always thought of it as if Ringer Equivalence Numbers were like Watts, that is, the electrical power required for and drawn by the bell/ringer/chime/etc during ringing. For example, if you have a power supply which will safely supply five watts, you can add any combination of loads which total no more than five watts. Each household appliance, for example, is rated X watts on its nameplate and consumes approximately that much. Add the watts of the appliances on a circuit to find the total and check if the circuit can safely supply that much. It's possible to build an appliance (ringer) to consume fewer watts by having a more efficient design or by providing less output (noise.) Most physical bells are designed to use 1.0 REN's because that's the way they've been for years and it's an acceptable standard which is fairly cost-effective to achive. Most "chirpy" ringers use less because they are electronic and peizo-electric (more efficient and, IMHO, more annoying) rather than electromechanical like the standard gong-style bells. Or, some of them on "powered" phones use amplifiers which cause some of the watts come from the AC power supply instead of the phone line. The Phone Company's (Central Office) Switch or a PBX, or whatever is driving the bells, shouldn't "care" how much you're using as long as you're under the maximum rated "load" - more load will just draw more current. Of course, as you approach the maximum load or surpass it, there will be significant voltage drops and/or current increases (Ohm's law) which will result in not enough voltage to ring all ringers and/or activating a "circuit-breaker" or equivalent overcurrent protection circuit in the switch or pbx. I've always heard that the "standard" switch or pbx will power about five REN's worth of ringer-load, but I've had six or seven hooked up before. I've also noticed the performance of the bells degrade as you add too many, due to low voltage. If the REN's are smaller per phone, or on the average, then you can add more phones. So, you should pay attention if you are approaching five or more REN's on one line, but this isn't a problem for most people. I've never seen a bell with greather than 1.0 REN, except maybe some oddities I build myself, which the FCC never tested. :-) A side note: Due to inexpensive construction, most cheap electronic phones with non-gong ringers (the J-Mart $8 models) will ring at lower voltages than they really should and often chirp when someone pulse dials on an extension phone (called bell-tap). They usually also have less than 1.0 REN's, but these are two effects from one cause (cheap but efficient all-electronic circuitry) rather than a cause and effect of each other. Todd Inch, System Manager, Global Technology, Mukilteo WA (206) 742-9111 UUCP: {smart-host}!gtisqr!toddi ARPA: gtisqr!toddi@beaver.cs.washington.edu