New Ferris Clock

Hi Folks

I'm thinking of making this fascination timepiece, the mechanicals are within my experience but those electronics frighten me!

Can anyone please tell me where can I buy all the bits and bobs necessary?

Is it difficult to make this circuit board? How the heck does one test and troubleshoot it?

Is it possible to buy a ready-built circuit board to do this job?

Any tips or clues would be gratefully received.

Roger

The only ferris wheel clock that I've come across was purely mechanical The clock was driven by balls in a ferris wheel and if I remember rightly one dropped every hour The owner then had to replace them in a trough at the top

I'm not conversant with any electronics being involved I look forward to others comments

Roy

Hi Roy, there is an electrical one by Dick Stephens written up very comprehensively in the ME in 2002, see

http://www.model-engineer.co.uk/news/article/ferris-wheel-clock/13812

The mechanical on to which you refer is, I think, called the falling ball clock. Hey, if you can find plans for that I should be very interested!!

Roger

Roger Sorry I've not seen plans I once cleaned one and set it up for the owner

But it should be possible to design one the wheel with the balls is only replacing either a weight or a spring

Food for thought Roy

It would help to mention the series starts in 5 April 2002 issue 4166 and the electronics appears in 2003 Feb issue 4188 page 156.

It is built on vero board and the article says "no knowledge of electronics is required." then fails to explain what it is trying to do and even involves an oscilloscope in the testing. Poor presentation.
Get the parts from Maplins.

So what is it doing. In effect it is like windscreen wiper control. If you flick the switch you want the wipers to go on and do a full run not stop half way across the screen. This circuit is to make it do one rotation of the ball lifting archemedian screw so it has a start switch, a keep going circuit, and a stop switch. Armed with this knowledge you can go to a 15yr old schoolkid and have them make one usig a 555 timer chip as their GCSE project. They do that stuff at school these days but they will probably want to use a microprocessor.

Why not do it without electronics? The sparking on switch contacts and high starting current for little motors is bad for switches life expectancy. This system uses low current in the switch and might get 1 million cycles out of it.

Hi Bazyle, thanks for the detailed reply, you give me hope in what is, for me, a mysterious subject.

I see in postings on "Ferris wheel electronic board" in November 2012 that certain modifications are suggested due to an error in the original and also for later improvements.

As I'm such a novice at this subject I don't know whether I should include the mods or not. Probably, is my guess!

Have you any idea what it would cost to get a board like this made, and where would I go?......other than school kids in the local college!

Also, might it not be better to power this device from the mains, transform it down to 12v, to save having the hassle and expense of those big batteries? But what do I know.

Roger

It's simple enough, I think the original arrangement may have been over-complicated. What is needed is a mechanical brush and track arrangement on the screw so that if the motor is started the brush makes contact and the screw turns one revolution until it returns to a (small) gap in the track. The ball itself is used to short out two rails and provide power to the motor long enough for the brush to turn past the gap.

I think the reason for the electronics was that the ball didn't make contact reliably or for long enough for the brush to leave the gap, with the obvious consequence that no replacement ball would be driven from the top of the screw.

As has been said, the web is awash with simple, reliable 555 timer circuits*.

Also, might it not be better to power this device from the mains, transform it down to 12v, to save having the hassle and expense of those big batteries? But what do I know.

As long as you don't fear the return of the 3-day week and power rationing

Neil

*These days you could replace the 555 with a microcontroller at less cost. In fact the microcontroller could replace the entire clock and be more accurate, but I don't think that's the point... hence my personal preference would be for a totally electromechanical solution.

I have only glanced at the electronics bit to see what it was so didn't realise it was battery powered. It is not a beginners project anyway so if you have the skill I suggest examining the rest of it and ignore the electronics. Then design a mechanical lightweight lever system that is knocked on by the ball as it passes and back again after one turn of the screw. Use that mechanism to move a small magnet to activate a "reed switch" and use that to switch low current to a single transistor to power the motor.
If you don't have confidence in a school kid then try

a) your ME club that probably has an electronics expert.
b) a local Amateur Radio club
c) students at a local technical college
d) local University students reading electronics. (hopefully there are some left in the country)

Even though I have been a professional electtonics engineer for decades I wouldn't put that much electronics in a model engineering style clock. Electro-mechanical like a Hipp etc is ok but not ICs 'cos they just don't last.

The "Painting by Numbers" approach to the electronics part of these articles was, I think, unfortunate.

However; the circuit is very simple and the devices used are robust.

If anyone is interested in following the circuit, rather than just assembling it; here are some recent NXP DataSheets for the chips.

HEF4528B

HEF4011B

Hope that helps

MichaelG.

Thanks to everyone who has responded on the Ferris clock; most helpful.............I hope that one day I shall be able to report progress!

Roger