For the bulb you can probably replace it with a W1A or AR-1bulb which is an argon bulb commonly used in old school contact printers they have a purple hue and also emit long wave UV light
I doubt if they are still manufactured but a photo shop or studio or chemist shop which developed film which has been in business a long time 60's and 70' is likely to have some as they were very common them Content by Scott Typos by Siri > On Mar 16, 2017, at 5:22 AM, Morris Odell <[email protected]> wrote: > > Hi all, > > I was recently asked to resurrect this interesting device by a colleague who > collects antique scientific instruments. It’s a "Chronoscope" made by the H. > Tinsley company in London in the early 20th century and used to measure time > intervals with the precision of those days. It's large and heavy in a > polished wooden case with a top deck that hinges up to reveal the innards. > > The timing reference is a large tuning fork about 30 cm (1 foot) long and > running at 25 cps. It's normally in a glass fronted housing (removed for the > video) that includes a pair of hinged mechanical arms for starting it. It's > maintained in oscillation by an electromagnet and contact arrangement powered > from a 12V DC supply. The fork amplitude is controlled by a rheostat - too > much and the tines impact on the magnet. The video frame rate makes the fork > look slower than it actually is. I was able to extract a signal and measure > the frequency with a modern GPS disciplined counter - it's 0.007% off its > specified 25 Hz! The frequency is too low for my HP 5372A so I was not able > to easily get an idea of stability or do an ADEV measurement. The fork has > quite a high Q and takes over a minute to stop oscillating after the power is > turned off. There's a built in higher voltage AC power supply, probably a > mains transformer, potted in beeswax in a polished wooden box inside that is > intended to > energise a large neon strobe lamp used to adjust the fork. Unfortunately the > lamp was not with the unit and is no doubt irreplaceable. > > The 25 Hz signal is filtered by an LC network and used to run a synchronous > motor in the Chronoscope unit. Synchronous motors not being self-starting, > you need to tweak a knob to get it going - there's a joke in there but I > can't for the life of me think what it could be 😊 The "Contact" switch and > associated socket on the back controls an electromagnetic clutch that > connects the clockwork counter mechanism to the motor and the contact "on" > time is indicated on the dials with 10 mS resolution. > > There's not a single active device in there and after a clean and lube it > runs very nicely from a modern 12V DC plugpack. My friend is very pleased > with it and it will take pride of place in his collection. > > I'd be interested to know if any time nuts have knowledge or experience of > this lovely instrument. > > A video of it is at https://youtu.be/i5S8WS9iN_E > > Enjoy! > > Morris > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
