Smiths Bakelite Radio Alarm Clock

[slderiron]

Saw this bakelite alarm clock at auction and decided to buy it. It was advertised as a wrking alarm clock, though as I've only received this morning I'll find that out later.

I was intrigued as to how such a small bakelite radio alarm clock could house a radio, and sure enough, once I've got into the back there is no radio.

I can't find anything out on the web, but I'm assuming the lead for the radio actually lead to an external radio, which was activated by the timing mechanism of the clock.

Can anyone advise if they have experience of this particular model of clock?

Many thanks, john.

[Darren-UK]

I've got two of those, in constant use and connected to TV lamps. The bakelite version, as shown, is the "Preston" model and it dates from 1950. There was a wooden version, named "Prestwich" (or Prestwick, I forget now). The idea was to act as a timer to switch on/off a radio, lamp, or any device which did not require earthing and up to a maximum rating of 5A.

Usually these clocks need rewiring and can be a tad fiddly in that respect. I rewired both mine but only fitted an earth between the mains and the clock; the output to a lamp or whatever remaining 2-core. It is possible to earth the output, of course, but it's clumsy. I use 5A 2-pin connectors to connect the output to the lamps (those same generic connectors which substitute on the DAC90A etc).

If fitting new input and output mains flexes, beware of the cutouts in the rear panel. It's advisable to enlarge them with a rat-tail file, or whatever, as the crude metal edge can cut through thicker modern cables over time. The original flexes were those transparent, twisted, single insulated efforts which required only small cut-outs in the rear panel. I have the non-timer version of this clock still fitted with an original flex .

The motor is self starting and of the infamous Bijou type, although they seem less prone to failure in this particular clock for some reason. The switch on the side is, obviously, for timer overide.

By the way, it is not an alarm clock in the accepted sense of the term as there's no integral alarm mechanism.

See this thread which shows a picture of the rear of one of mine.

Hope that helps.

[slderiron]

Thanks Darren. That makes more sense. As you can see from the pic, the wiring needs tidying up to say the least, though I see that someone lost a screw and decided to hard-solder. Not clever that.

Even with the additional info you've given, there's nothing on the web I can find relating to this type of clock. I guess they weren't made for long.

The two core lead dac90 socket is the way I'd prefer to go, if I can find one of these.

Would you happen to know where I can get instructions on how to set the clock, I'm going to connect to the mains tomorrow and see how she fares.

thanks, john.

[Hybrid tellies]

I ike it, that looks really neat. Well worth the effort to re do some of that wiring.

[Darren-UK]

Originally Posted by slderiron

Would you happen to know where I can get instructions on how to set the clock, I'm going to connect to the mains tomorrow and see how she fares.

Hi John,

These clocks are scarce although not exactly rare (the wooden version is rare) but instructions simply don't turn up any longer.

However, being familiar with these clocks I can give you the essentials. They're simple enough anyway. To give the clock a checkover, you do not need to apply the mains.

a) Being old, the first thing to do is check for any shorts between the plates of the movement and the mains input lead and then check the motor is in working order by putting a meter across the two terminals (where the missing screw has been botched with solder). The test for any shorts between plates and mains input will also tell you the condition of the wiring from the terminals into the field coil, this being the one dodgy area on the Bijou.

b) On the rear are two knobs, which I presume you've got. Looking from the rear, the righthand knob sets the timer switch-on when in. Pull it out against a spring and it sets the clock hands. The lefthand knob sets the timer switch-off.

Make sure the overide switch is off and check the mains output is open circuit with your meter. If it isn't, then check the hands are before whatever switch-off time is showing in the righthand window. If they are, turn the hands beyond switch-off time and recheck.

c) Next, set a switch-on and switch-off time. Having done that, turn the hands to around fifteen minutes before switch-on time. From there turn the hands slowly towards switch-on time, at which point you should hear a quite loud 'clunk'. Check again with your meter the mains output, you should now get a reading. Check, when you hear the clunk, that the hands correspond with the switch-on time you set.

If all is well, continue turning the hands towards switch-off time doing, as before, the last bit slowly. You should then hear a similar clunk as the timer switches off. Check again the mains output, this time to make sure it's open circuit again. As stated above, all this can be done without applying the mains. This is advisable given the state of the wiring.

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The overide switch, despite age, is reliable. Nevertheless, do a visual check to make sure the wires, or any stray strands of wire, are clear of the metal parts of the switch.

When fitting the 5A 2-pin connector, don't forget to fit the female to the clock output. Also, if you intend using it to control an AC/DC radio note which wire is connected to which pin. This is obvious, of course, but I'm mentioning it here for the benefit of others as this is a public thread.

Regarding the mains output, you can fit a 3-core lead if desired but it'd be rather pointless; no good for an AC/DC radio and few lamps are earthed unless they use a metal bulb holder. The mains input earth I usually connect via a spade to one of the nuts securing the movement plates. If you do decide to fit an earthed output, this can also be anchored to the plates.

That's about it really, hope it helps and let us know how you get on.

[slderiron]

Thanks for this Darren, this is very helpful, I'll report back once I've done the tests, regards, john.

[slderiron]

Blimey, works perfectly. Did all the checks as outlined and it all checked out, wired a lamp on the return lead, set the timers, and it all worked! I paid £40 with postage for this clock, which I thought might be a bit steep, but as it actually works I'm pretty pleased with it.

I've posted a couple of pics;

the black pointers are touching the areas in the clock I am going to split the earth lead, one attaching to a holding nut on the chassis, the other part of the earth attached to the toggle switch. Would you say this is the best way to earth the clock? I found that the gap for the live/earth is already quite tight, and it seems the only way to feed an earth with live and neutral is to widen the hole. I really don't want to alter the clock at all, but safety being priority I feel I don't have any other option.

The other pic shows the bodgy solder connection where a nut should have been used to connect the wire. It appears the solder goes down a fair bit.... any further I suspect the mystery bodger would have wrecked the coil. I think that any attempt to remove the solder may result in wrecking the coil and I'm inclined to leave it well alone, given that the clock is in perfect working order. I'll tidy up the rest of the wiring as best I can.

Now I just need to get a male and female DAC90 type connector.

[Darren-UK]

Those Bijou terminal blocks catch out the unwary as the design is not what you'd expect. The tags are secured by rivets to the block. The hole in the tags is threaded for the clamping screw and the holes within the terminal block are just blind clearance holes. Overtightening of the screws, unsurprisingly, causes the thread to strip - which is likely what's happened where one of your terminals has been soldered.

See one of the attached images which I've just taken for you. I've removed one of the screws and you can just see the screw thread in the tag.

Moving to the second image, you can see the wires from the terminals passing through to the field coil. This is the dodgy area on these motors which I mentioned earlier. Note the wires are quite tight over the edge of the motor backplate. As can be seen, what I did here is slacken the wires slightly and add a bit of heatshrink for extra protection. I'd advise you to remove the motor and check the condition of these wires; if something's going to go bang, that's the likely cause.

On the switch earthing matter, it was literally years ago when I rewired my clocks but I recall doing the following:

I ran mains earth to one of the movement backplate nuts and from there ran another wire over to the switch. I then took one of those thin metal washers you find on telescopic aerial connections, soldered it to the wire and fitted it between the switch and the inside of the bakelite casing.

Glad the clock works anyway and hope the images help.