Antique Mall Western Electric 202... $20.00...One "Small" Problem

[bingster]

 The information I have states that #38 ringers are designed to be used only on magneto lines.  That doesn't mean it won't work, it just means that I don't know if it will.  There's only one way to find out!

[Phonesrfun]

They will work with a .5 to 1.0 mF capacitor in series, however, the lower resistance than modern ringers will mean they suck up a bit more of the ringing current.  Modern POTS phone lines are generally limited to a REN (Ringer equivalence) of 5.  A modern 500 phone has a REN of 1.0.  That means you can easily have 5 phones with ringers hooked to the line with no problem.  An older tinger could have a REN of 2 or slightly more, thus limiting the total number of ringers you can hook to a line.

What happens if you exceed the REN of 5.0?  Do the phone police show up at your door?  Do the phones stop working?

First, there are no phone police.  We thought there were back in the 1960's and 70's, but they have all take early retirement.  No, no phone police.  What may happen varies from situation to situation.  The worst effects are:

Lower ringing currents affecting all ringers, thus lowering the ringing volume; or
Busy signal to callers where the load of too many ringers make the central office equipment misinterpret this as an actual phone off hook.

In these days of Voip services provided by cable companies and others, the routers that supply ringing current are more sensitive to the higher loads since they are not as robust as an actual phone company central office at generating ringing current.

Magic Jacks won't even develop enough oomph to ring a "standard" 500 set.

All that being said, I go with what Bingster said and just go for it and see what you get.

[GG]

You can raise the ringer impedance (thereby lowering the ringer equivalence) by adjusting the value of the capacitor, or adding a resistor, in series with the ringer coils. 

This will usually also require adjusting the distance between the bells and/or the other mechanical parts that determine how far the clapper can pivot between the pole-pieces on the coils.  Usually that's a matter of loosening a screw and carefully sliding the clapper mechanism "in" toward the coils, and then re-tightening the screw to fix it in its new position.

Re. the use of mini-networks:  there are a few folks around here who highly object to that practice, but IMO it's acceptable if it doesn't require drilling holes into original equipment or otherwise modifying it in a manner that can't be undone subsequently.  Personally I like the variation in the subtleties of the audio that results from using the original equipment wherever possible, or if need be, using an R/C network (resistors & capacitors, sometimes referred to as a "cheater" circuit, though Ericsson used it in the PAX version of their N-1900 telephones so IMO it's a legit technique). 

[Rigger1]

Ok...so it can be done. I agree that i don't want to modify the ringer box any more then needed. The box I have is from a flea market and is empty except for the wiring. It is painted flat black, so it is in pretty rough shape. I have a 425E network dated 5-68, and a pair of old ringer bells I found somewhere. I am fairly sure they are model 38B. I also have what is left of the 302 that I took the dial out of that is currently in the B-1. It is however really rusted up. I understand that I need to get a 1/2 to 1 Mf capacitor. That should be fairly easy, radio shack is my first thought on that. Here again is where I hit the wall. I have no knowledge of electrical wiring. I am schematically challenged to say the least. If any of you kind gentlemen or ladies can give me a basic instruction I would really like to try this. i am going to attach a picture of the wood case, bells, network, and the 302 remains. Thanks to everyone for their input, I really am learning here.  Bill

[bingster]

Okay, I think you've got a winner there.  There's no need for an extra capacitor, as the proper capacitors are built into the network you have in the photo.  In fact, the ringer and network are all you need.  If you scroll down this page, and follow the "685 subset" diagram, you should be good to go.  

http://www.classicrotaryphones.com/forum/index.php?topic=784.0

Obviously with a ringer that old, you don't have four ringer wires as the diagram shows.  Just connect the red and black as shown, and I think that will be fine.  There will be no need to attach any of the cords to the original contacts in the subset.  As you can see in the diagram, all connections are made directly on the network.

[Rigger1]

Wow! Thanks bingster!  That is easy enough for me to follow with out a problem. First chance I get I will wire it up and report back. I am excited about this.  Bill

[GG]

Wow, Bingster, that's outstanding!

Question about the use of 425-E networks:  The jumper from L1 to RR, bypasses the capacitor between RR and F that acts as a spark quench for the dial pulse contacts.  In that case, what's replacing that capacitor? 

Your diagram of the 302 base also tells me what I need to know to replace a blown-up capacitor in a 5302 with 1937-dated parts inside: one 1.0 uF and one 2.0 uF capacitor, wired thusly.  I may have them lying around, otherwise a trip to the local electronics shop for parts.  Question: do you know if the capacitors used in 302s contained PCBs?  (If so, there's dioxin in there which is carcinogenic as hell and has to be cleaned out carefully.) 

[Phonesrfun]

Wow, Bingster, that's outstanding!

Question about the use of 425-E networks:  The jumper from L1 to RR, bypasses the capacitor between RR and F that acts as a spark quench for the dial pulse contacts.  In that case, what's replacing that capacitor? 

Using a 425-B or -E network in place of an induction coil does take the RF/spark capacitor out of the circuit, but you have no choice unless you want to run more wires to the network and have more connections inside the base of the phone.  Remember that a stock 302 with the 101A inductor had not built-in RF/spark filter, and neither did the 534/584/634/684 subsets.

[Rigger1]

I gave it a quick try this morning, I didn't attach a phone, I just wired the ringer.  The ringer has 2 terminals, (one on each coil) so I hooked one to red and one to black as shown in the diagram. The house phones were "off the hook" Is this because I didn't have a phone attached to the network? I will try again when I have more time, but I wanted to get started. Thanks,  Bill

[GG]

Re. Phonesrfun:

What I was thinking about was:  Assume a conventionally wired 500.  Now you unscrew the blue wire from the dial to terminal F on the network.  This produces the identical result to flipping the talk/monitor switch on a test handset to the Monitor position: you can hear stuff on the line without triggering dial tone.  So you can hear incoming 20 Hz ringing, you can hear outgoing call progress, you can hear conversations.  You can say "when will those people get off the line?, I have to run some tests now..." and they won't hear you.

The capacitor in the network between F and RR is conducting all of that AC: the ringing signal and the conversations etc. etc.  The purpose of that capacitor was to prevent the dial pulse contacts from sparking, since sparking wears down the precious metal contact points more rapidly, thus making the dial go noisy and generating a field service call to replace the dial. 

Now you have a 302.  You unscrew the transmitter cap and take out the F1, and lo & behold it behaves the same way as the 500 with the blue wire from the dial unscrewed from the network: it goes into "monitor" mode.  This had made me think that the dial in the 302 was similarly protected.   I have a 302 with #6 dial sitting about 14" from my right elbow so I just did the empirical test (I've been playing with 302s since I was a kid, which is > 30 years ago, surprisingly I never bothered to test this aspect until now). 

Low & behold, you're quite right: unscrewing a wire from the dial pulse contacts makes the receiver go silent rather than into monitor mode.  Holy cow.  No capacitor across the dial pulse contacts.  So all I can think of is, the ringer circuit must have provided some degree of spark quench.  Otherwise what you have are dial pulse contacts going bad and a full employment act for repair techs.  Or did I miss something else too?  Or should I run around putting 0.5 MF capacitors across the dial pulse contacts on my 302s and other WE sets of that era? 

(Know what's weird?  My GPO 232 went missing.  I've been looking all over the place for it, and two "706s" (Ericsson N-1900 PAX model), and it looks like the three of them all went off some place and hid.  I have one more place to look tonight.  That or I'm losing my mind ; - )