Friday 28th Dec… a birthday invite from one of J’s friends.
Was thinking there could be plenty of ‘doctors’ present and considering the general age – probably the ‘Baker’ variety.
Couldn’t think of an easy to produce idea until the day before (and no access to large format printers anymore). On a walk I had a brainwave, so we took a detour to Tescos and purchased a pack (5 pairs) of ladies knee length tights for the grand sum of £2 ! Then stuffed them with tissue paper and held together with a couple of elastic bands.
All in-keeping with the good ole days of Dr Who monsters / Blue Peter card and sellotape!
Not forgetting something black to wear and a sigma graphic cut from a piece of silver card.
Add a ‘Moon desk light’ (watch battery powered), plus a USB extender cord, stuck together with a foam sticky pad for one prop, then a Christmas battery powered Christmas decoration – with addition of a cable tidy for the second prop…. and voila!
Ood do you think we are!
A hand-made K-9 made a surprise appearance also…
We were something of a hit with the kids!
Loved this – a Tardis, painted onto an (empty) Jack Daniel’s whisky bottle (plus Weeping Angel !)
The kids liked their (chocolate) rocket…
And we took a few bottles of some space themed drinks for the adults too…
Today, I have added an on/off button to the battery pack Ed made for me. I have used a car/lorry 12V on/off button from Halfords, 25A cabling and connectors. This button goes between the 75AH leisure battery and inverter and is meant to avoid the situation where I accidently leave the inverter turned on draining the battery as happened to me recently. It took quite some time to get this working although for some reason I have not managed to get the 12V light to come on on the switch when it is turned on. More accurately, I did get that working too when the switch was not installed on the side of the case but it has not worked since I drilled the hole and screwed it on to the case!
The location of the switch below the plug sockets is to avoid the switch foulibg the handle of the case.
Ed Mann built a fantastic battery pack for several members of RAG including myself. These packs are based around a 75AH leisure battery and provide 12V and 230V outputs abd plenty of juice to power anything we need in the field from mounts to laptops.
However they are quite heavy. To help with transpirt i purchased a Homebase foldable sack truck.
There was still a problem left – the battery pack is housed in a plastic box that tends to slip on the sack truck and fall off. Bungy cords provided part of the solution and today I added the second aspect: I glued 3mm rubber sheet to the bottom of the battery pack and now it will never slip again! To acheive this, I had to empty the battery box first before I coukd turn the box over, but I got there eventually and aI am pleased with the result.
Today, I housed the new calibration light – I put four of the RELCO starter neon bulbs in the lid of a box – I attached them to a connection block inside the box.
In this way, I have four neon bulbs ready to use. I only connected one at a time. Each bulb has life span of 90 hiurs do when one burns out, moving the wires indide the box to the next bulb along allows the calibration light to continue to ne used.
As mentioned in the previous post, I have added a boc from ebay which will turn off the light after twenty minutes preserving the life of the bulbs when I inevitably forget to turn them off on the field!
The whole set up runs on 240V via an inverter on a leisure battery. I have ordered a RCD for safety and used boxes designed for external use and sealed all holes with a glue gun to minimize moisture ingress.
My first calibration spectrum taken using the above can be seen at this post, which follows on from the above:
Please note this project uses potentially dangerous/life threatening 240V mains electricity supply – please ensure you are qualified to work with this or ask someone with such qualifications to do this work for you.
The following is a description of what I did rather than a recommendation for how this should be done.
My modifications required began with my removing the neon bulb from its RELCO flourescent light starter casing and attaching 2 x 47 Kiloohm resistors in parallel to one limb of the neon bulb. The bulb is then simply connecting to 240V supply. Once I confirmed this worked, I connected a delay switch unit – this automatically switches the light off after 20 mins to preserve the life of the bulb as the neon bulbs in these starters have a life expectancy of only 90 hours each.
The delay switch unit is the box with printed circuit in the last photo – I did not make this but bought it off eBay.
I now need to mount the bulb in a housing so it can be safely used outside for calibrating my spectrometers at the telescope.
The photos below refer to the above process.
There is a follow up post available to the above which describes the completion of this project:
A couple of months ago I brought my ‘work in progress’ scope along to an introducing astronomy night.
I’ve had to teach myself anodising to finish it, I’m quite pleased with it, although I’m going to have to do some more tuning of the speed reducer – the ball bearings are causing the grooved stainless steel rod to distort making it go loose. I have a plan but it means making or finding a specially shaped grindstone.