Amateur Telescope Making & other do it yourself projects

ATM & other do it yourself projects

Modifying RELCO fluorescent starter to make homemade neon spectrometer calibration light part II (RECLO SC 480 S53993)

This follows on from my previous post on this subject.

Modifying RELCO fluorescent light starter to create neon calibration light for spectrometry

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:

First calibration spectra from RELCO neon starter bulb (RECLO SC 480 S53993) taken with Science Surplus DIY Spectrometer 9/9/2018


Modifying RELCO fluorescent light starter to create neon calibration light for spectrometry part I (RECLO SC 480 S53993)

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.

All worked!

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:

Modifying RELCO fluorescent starter to male homemade neon spectrometer calibration light part II

And the following one shows the first calibration spectra taken with the new calibration light:

First calibration spectra from RELCO neon starter bulb (RECLO SC 480 S53993) taken with Science Surplus DIY Spectrometer 9/9/2018


Welding an acrylic diffuser tube for homemade compact flourescent bulb spectrometer calibration lamp

Not sure how well this is going to turn out…

Rhys and I have had a go tonight at welding two pieces of acrylic together to create a diffuser tube for our homemade calibration lamp.

Acrylic welding involves using a solvent to soften the plastic so it melts together along the weld and form a single piece of plastic.


I’ve Finished my ED 66 scope

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.

Expect cloud for along time…

Sliding Dewshield
Sliding Dewshield


The Skywatcher 66ED lens cell
The Skywatcher 66ED lens cell


WO scopes only have a thermometer :-)
WO scopes only have a thermometer 🙂

Ed changes the heat power control circuitry on the laser pointers he made for Damian and Andy

Ed’s laser pointers with integratedvheater straps and powered from 12V car battery thay he madr for Damian and myself are fantastic. However the power transistor gets quite hot so he came around yesterday and swapped the transistor for a small board that switches power on and off at high frequency so that less power is used and it does not get hot. Works brilliantly! Thanks Ed. This is what we should be able to buy commercially but can’t….


Mid-monthly RAG meeting 24/8/2018

Lee and Nick talked about 6 objects to observe in night sky and various telescope finder devices including Lee’s homemade version of a device similar to a Telrad – a beefy version with 50mm binocular lens in it, 1/10 wave mirror and in-built heater! He is suggesting a workshop to make our own versions of the same but improved over the commercial original- sign me up!

After Lee and NIck’s talk, I gave a brief demonstration of the DIY Spectroscope – thankfully it worked producing instant spectra for the lights in the room!


Nick Cox (left) and Lee Bale (right) give their talk at RAG:

Rhys tries out Lee’s homemade version of  Telrad finder:

Making a device to connect the fiber optic cable from the DIY Spectrometer to a telescope & adding in some way to guide it in use – Part 1, Attempt 1

I have labelled this post as:

“Making a device to connect the fiber-optic cable from the DIY Spectrometer to a telescope & adding in some way to guide it in use – Part 1, Attempt 1”

The reason for this is that I am sure there are going to be further parts…..and equally sure I will need many attempts to get each part to work – if I ever do!


The “DIY Spectrometer”:

Changing the fiber optic cable:

First up – the cable that came with the “DIY Spectrometer” was not long enough so I needed to purchase a longer one – one that will reach from a table to the telescope eyepiece – the old cable is 50cm the new one 200cm in length – just a cheap plastic fiber optic cable from ebay with SMC connectors (the DIY Spectrometer has SMC connector on it for the fiber optic cable).

Cable that came with the DIY Spectrometer:

New cable from ebay:

Guiding the spectrometer:

In order to guide the telescope during spectroscopic observations, I purchased a beam splitter – could not find one in UK so this one came from Italy. It is 1.25 inch fitting:

For guiding purposes, I have bought cheapo variable-illuminated eyepiece off ebay again (Chinese and emphasis on cheap – 12.5mm lens in it):

Connecting the fiber optic cable to the beam splitter:

I purchased a cheap Cheshire eyepiece from ebay (again!):

I used my drill press to drill out the hole in the top of the Cheshire eyepiece so it could accommodate a SMC-SMC connector:

Drilled out hole in Cheshire eyepiece:

Drilled out hole from inside of Cheshire eyepiece:

I tried to tap the hole to fit the SMC-SMC connector (from Ocean Optics, USA):

Tapping did not work too well and I ended up with slightly too big hole so SMC-SMC connector fitted inside without needing to screwed on.

However, a small piece of black electrical insulating tape wrapped around the bottom and some Gorilla glue later and it is a tight fit and I think it should work well.

The top plate of the Cheshire eyepiece (which I have drilled to accommodate the SMC-SMC connector) unscrews – removing it shows the SMC-SMC connector projecting through the plate and an area that I was able to fill with glue from my glue gun in order to further adhere the SMC-SMC connector to the plate.


The Cheshire eyepiece has cross hairs at the front, which help it to perform its function as a collimating device:

These cross hairs do not help with its use as part of a spectroscope. They simply obscure light from a star directed at the fiber optic cable. Therefore, I removed them:

The opening at the front of the Cheshire eyepiece simply lets light in and that was no use to me so further black tape to cover the hole was necessary. I also removed the rubbish eye ring from the top of the Cheshire eyepiece:

The following photo shows the whole lot put together, with fiber optic cable attached. It looks good but will it work? I will have to see!