Trimphone.

[Stephen Furley]

I've just acquired a 722 Trimphone, said to stand for Tone Ringer Illumininated Model.  This is the radioactive telephone, though I don't know if there's any trace of radioactivity left in mine.  This is my first Trimphone; I don't really like them, but they're enough of a classic to deserve a place in the collection.  The original field trial model of these goes back as far as 1965, and the works were based on the 706, but with the tone ringer in place of the bell.  The production models were based on the 746 components.They were intended mainly for home use, but were to be found in some businesses, mainly 'arty' ones; you'd be quite likely to find one on a graphic design studio, hairdressing salon or architectural practice.  They could be fitted with a recall button, though I've never seen one which was.

It was much lighter than a normal telephone, and tended to slide about when dialing.  The plastic mouldings of the handset did not fit very well on many of them.  They couldn't be used with acoustic couplers, something that was still quite common in those days.  The transmitter and receiver were smaller than usual; the receiver was in the normal place, but the transmitter was just below it, in fact they overlapped each other, and faced in opposite directions.  There is a voice tube inside the handset leading from the mouthpiece up to the transmitter, in much the same way as in a telephonist's headset; indeed, the transmitter and receiver were originally designed for use in a headset.  The linecord is still fittedto this one, it has not been converted for use with a BT socket  The cord is part straight and part coiled.

[bingster]

That's space-age design if I ever saw it.  It's quite artistic, as you said.  Perhaps a bit too much for me, too, but a very interesting design, nonetheless.  What's this about radioactivity, though? 

[McHeath]

Yeah what's the deal with radioactive? 

I like this phone, very 60's, an exuberant over the top design.

[contraste]

The radioactive thing is to do with a glowing dial. Over time the radioactive material becomes exhausted or perhaps leaks away and the dial glows no longer.

[Stephen Furley]

Yeah what's the deal with radioactive? 

Contraste is correct; there was a tube of radioactive gas, Tritium I believe, behind a translucent dial plate to illuminate it.  Never did seem to work very well, and there's no hint of a glow from mine now.  It was said to be about as radioactive as a luminous watch, and having one in the home wasn't a problem, but there was a limit placed on how many engineers could have in the van at a time.  How they managed in the factory, where there would obviously be a large number of them, I don't know.  The biggest problem it caused was for BT when they came to scrap the things; there were a couple of locked skips in a car park somewhere containing several thousand of the dials, while they worked out how to dispose of them.  I seem to remember that somebody was prosecuted for illegal storage of radioactive waste over it.

It was just typical of the Trimphone, it was designed to be looked at, not to be used.  Having a Trimphone, I was going to say owning a Trimphone but of course you couldn't own one, you could only rent one, said something about you, you were trendy and 'with-it', which seemed to matter in the '60s and early '70s.  Later push-button versions were made until the libralisation of the early '80s, when all sorts of other designs became available.  Recently, reproductions have been made, which I think have a dummy dial with buttons fitted in it, similar to the reproduction 746 which Geemarc make.

Some of the problems with it included dialing often being a two-handed process due to the 'phone sliding about, being so light as to be easily pulled off the table by the cord when in use, sound quality was not as good as with a conventional 'phone, the transmitter was noisy - the long blue component was an attempt to improve this, it was fitted from new to later models, and added to earlier ones when they were refurbished or repaired.  This component wasn't fixed it any way, it just hung on its wires, and lay on top of the circuit board even when fitted from new.  The handset was so light that it didn't always operate the hookswitch correctly, as you can see in the pictures the thing that operates the switch had to be pressed down a long way, it was designed so that it could be used as a carrying handle when the 'phone was in use, but it sort of flapped about, and felt odd.  The plastic mouldings didn't fit very well, it was easy to get wires trapped when replacing the cover, the part-coiled line cord tended to get tangled up,and it cost more to rent than a normal 'phone.  In just about every practical sense it wasn't as good as a 746, except that it took less space, and it looked trendy.  I quite like the look of it, but it wasn't a design that I would choose for a practical telephone.

The N-diagram for this model shows lots of minor changes in a short period of time; they were obviously trying to fix some of the problems with it.

[Tonyrotary]

Is this the model that with each ring  the ringer gets louder?

[contraste]

The Trimphone had a warbler which could be adjusted for volume. I don't think it increased in volume as it rang but I'm sure Stephen will be able to answer that.

[Stephen Furley]

I don't know; hold on while I wire it up and run up Skype on the laptop to call it...

... No, it doesn't seem to get louder, but I think I've read somewhere that it did; maybe later models did.

It has three positions, Off, Soft and Loud, and loud is unpleasantly loud.  I've never actually heard a Trimphone ring before, and this is something else that I don't like about it.  It's said to be a 2 kHz. tone modulated by the 25 Hz. ringing current, but it's a shrill, horrible sound, not a pleasant warbling sound, a bit like a bird singing, which I was expecting.

The N-Diagram says that the ringers are supplied with the off position disabled, and gives instructions for enabling it.  It was probably left disabled on the first 'phone, but enabled on extensions.  At one time you could only have a bell on/off switch fitted on extensions, and in the days when most 'phones were hard-wired, but a plug-in option, known as 'Plan 4' was available, only extensions could be plug-in.

I've just bought a rather expensive LD push-button one on Ebay; watch this space for pictures.  Now all I need is the DTMF one, the field trial model and the reproduction one.  A field trial one was sold on Ebay recently, but went for a high price.

[Ellen]

a couple of locked skips in a car park somewhere

skip = dumpster.

[Stephen Furley]

My second Trimphone, a LD pushbutton model, arrived today.  I'll try it this eening and see if the ring gets louder.

[HobieSport]

My second Trimphone, a LD pushbutton model, arrived today.  I'll try it this eening and see if the ring gets louder.

Be careful. Maybe the second Trimphone get's louder and louder until it finally explodes and spews radiation?  Sorry, a joke in poor taste.   Slightly more seriously, I would think that a self amplifying and "demanding" ringer feature such as that might be rather difficult to tolerate, not unlike a whistling teakettle, or my cat when he wants to go out.

[GG]

On my example of the Trimphone, the ring does indeed start out soft and get louder.  This was a highly useful feature for phones in bedrooms and other quiet locations, as it reduced the "startle factor" when the phone rang.  (Note, the ringer draws a lot of current and may not work on some PBXs.)  I think the chirping sound is quite pleasant compared to the rather harsh warble of some of the later models (for example one of the ones in the Statesman series, o-u-c-h!).  (It may be that the example you have uses the latter ringing tone?  Hard to tell unless we both posted recordings.)

The radioactive dials were adequately bright when they were new, but the reason they have become dimmer over the years is that radioactive materials decrease in their radioactivity over a period of time.  The "half-life" is the figure that tells you when the radiation has declined by half. 

The downside of the Trimphone's clever receiver design was that covering the mouthpiece does not prevent the other person from hearing an "aside" conversation in the room.  The other downside is that it's nearly impossible to hold on the shoulder, unlike the conventional US and UK (and other countries') receivers at the time. 

These were not intended as a replacement for the 706 and 746, but as a specialty model for bedroom tables and some office environments, in a manner analogous to the Princess and Starlite in the US. 

[Jim Stettler]

I have always liked the look of the trimphone.
I would like to get a clear one.
JIm

[gpo706]

GG is correct, my three all have ascendingly loud rings if left on the "loud" setting, even through my Pana 616.

Also you need to remove the lower circuit board to get at the screw on the wheel to release the "off" position.

All the dials on mine no longer glow in the dark, where does one buy Tritium? hehehe

[GG]

Methinks if you try to buy tritium, you'll get a visit from the Metropolitan Police's terrorism investigations officers.  Or in the US, the FBI. 

Aside from that, working with radioactives is highly not-recommended for people who do not have special training.  Radioactive materials are safe when handled properly, but you need special clothes, negative air pressure in the room, filtration of outgoing air, a respirator, etc.   The best way to get a dial to glow from radioactivity is to have a nuclear power plant nearby and then use the electricity to power a light under the dial. 

That said, there is probably a way to fit tiny blue LEDs into the center of the dial mechanism such that the dial fingerwheel itself glows at night.  I did this with the dial on the 80E in my bedroom when I was a kid, using a 1a2 lamp powered over the 2nd pair in the phone cord.