Motors and boxes

I have been experimenting with my vision for a motor to go inside the torso, so that Barbie can be attached to the end of a rod which moves through the neck.  The two wheels are made of mdf with ply rims and the drive belt is made from an bicycle inner tube.  The motor is a 12v 15rpm motor but I can change the rpm by varying the input voltage as I want Barbie to appear and disappear quite slowly.  The metal shaft on which the large wheel is mounted has two skateboard 6mm bearings on its fixed mount to minimise resistance.

I have also had to rethink my donations boxes.  I had thought the glass maker down the end of my road would make them inexpensively, as he talked about it being an easy job and he would glue them in place.  However, his quote is way beyond my budget, so I am making them myself, with 8mm clear acrylic.  They are standing on beach offcuts from a work surface, 500 mm high and 22 mm wide, with a mesh top to which I am attaching various devices.


Latching Relays are the answer

I have spent ages during this project trying to make simple coin operated devices.  I thought, wrongly, that channelling a coin down a route which meant it would straddle a gap between two metal contacts could reliably complete a circuit and whatever device was within that circuit would be turned on, albeit momentarily.  A day spent wobbling bits of metal together showed this theory didn’t work.. a switch needs to have a much more definite controlled action, the contacts I was making sometimes worked but generally did not. 

Tim Hunkins website provided the answer here .  The long wire movement operated switches were the solution I needed, switch number 339-207 from RS components (about £3.20).  This provided the means to reliably switch on anything by dropping a coin through a slot (1p, 5p and 20p less consistant than larger coins).  This enabled the 20 second recording modules purchased from Rapid Electronics to work inside my donations boxes.  The link to the part number for these is here (about £6.50).  I cut the leads to on/off button and wired them onto the terminals on the wire movement switch.  The speakers are small and rubbish sound quality, so for most of these units I have replaced them with small mylar speakers VC86T purchased from Maplins (£2.50).  This has enabled the simplest element of the project to be realised, donation boxes that come with sounds attached.

However, a momentary pulse of power as supplied by the activation of the wire switch is far too brief for any motorised action to take place.  The solution, after mucho head scratching (mostly the cats heads), I reread a book titled Cabaret Mechanical Movement by Aidan Lawrence Onn & Gary Alexander.  In their book (on page 105) they talk about the need to build in a latching relay circuit.  Well I took the book to Maplins and explained I wanted a relay to make a latching relay circuit, and they didn’t have a clue what I was talking about!  However, thank God for Ebay, where I did find what I was after: NAIS DR L2 3V, five for £9.85The next issue was how to wire it up.  These relays need to be soldered on to copper strip board as there are 8 tiny pins and no way to anchor the slippery little things.  My soldering is now much better than it used to be!  I blew up the first relay as I put 6v through the coils and I noticed after a while the relay was getting very very hot and didn’t work..I had wired it wrongly as I didn’t understand how the switching was supposed to happen!  I had to consult guru John Philip for yet more help and he drew me a diagram.  When I followed his instructions with a new relay it all went a lot better and finally I had movement.  Below is a photo which includes the latching relay, the vero board with terminal pins all soldered on and the coin trip switch recommended by Tim Hunkin.

and here is John’s wiring diagram showing how a smaller voltage works across the two coil switches and a larger voltage through the motor.

Kilted man project

New scheme..

I wondered if I could borrow my uncle Toby’s sporran for this project.  I can’t as it is not around any more, but to my surprise and joy the rest of his dress kilt outfit is, Lochaber tartan kilt. waistcoat, jacket and socks.  Had his sporran been available I am sure it would have been like my fathers and relatively understated, so not really what is wanted! 

I have purchased a mannequin for £11.50.  He arrived tightly wrapped in black plastic, revealing all and caused the postman and our neighbours hysterics.  A fine figure of a headless torso….

My plan is to have a collection box at the feet of the figure, and when money is dropped into the collection box a Barbie doll will emerge out of the neck to say thank you.  It will be a means of saying ‘Thank You’ to givers, the museum needs the money after all, it will make people laugh, it will send up some of the mythology, and with one stereotype appearing out of another..the whole idea tickles me hugely.


Roland Emett was a cartoonist, designing amazing machines, but better than Heath Robinson, he actually built them.  Several are still in use today around the world, including 8 in Ontario Canada.

Here is an archive clip of a flying machine he built.  I once spent a year rebuilding an airplane that had crashed.  I then crashed it again on the test flight, which it failed.   I feel Emett and I may have something in common when it comes to building airplanes.


There are short clips of some of Emmets other machines at this address.


Following on from seeing all the work in the cabinets I was thinking if I made a cabinet with coin operated devices in them that would fit in well with the museum.  Some cardboard models of ideas from my detailed visit to the museum were inserted.. a steam engine intended to travel upwards as a bicyle wheel rotated; an ornate bejewelled sporran with perhaps furry inhabitants that might pop their heads in and out; a model of the museum which would light up; and a model of the museum birching table..although that idea didn’t fly as I couldn’t envisage a way of portraying this in action that I did not find repugnant.

However, the deadline for this project within the college is 22nd February, ie 3 weeks.  The feedback from tutors today was clear, there is no way this is going to be ready for presentation to the public in 3 weeks, it is far far too complicated. Fantasy meets reality..time for a rethink. The tutors came up with suggestions about how to build on the work thus far.. but there is another missing element for me, as with my earlier gifting machine design.. it lacks bite somehow, it is a bit too bland, light entertainment. 

 I still think this would be a good way to give pleasure and earn funds for the museum, but it will need to be done outside of term time as huge amounts of problem solving will need to take place.