driving glow-starter with very low voltage

[Hamish Barker]

For those using the glow-starter bulbs from fluorescent tubes, I found an excellent way to drive them with low voltage: EL wire drivers.

EL wire is electro luminescent wire. it is available at electronic hobby shops, online etc. the wire has a central wire conductor, an insulating sheath with phosphor material, conductive sheath of fine wire, topped with transparent insulation. People use it for decorative lighting including wearables. it requires about 15mA per meter of length.

https://www.youtube.com/watch?v=RJ2xGFfrND0

Anyway, we are not so interested in the wire as the drivers.

The EL wire requires AC voltage of about 80+ volts from 50 Hz to circa 10khz.

Small packaged ac inverter drivers are available running on AA batteries, but I guess can easily run on 5V usb etc. cost is just a few dollars, even under a dollar on aliexpress for 12v powered ones.

I bought this one locally and it gave the measurements indicated further down this post:
https://www.jaycar.com.au/el-wire-power ... t/p/SL2440


not sure what voltage and frequency this aliexpress one operates at but I guess it
https://www.aliexpress.com/item/1005003 ... 2484%21sea


I tried driving my usual fluorescent tube glow-starter (Sylvania FS-14) which has hydrogen and argon lines, so it's very useful, although the h alpha line is rather bright compared to the argon. usually I am driving this with 240v and a series resistor of about 24kohm (more or less, I can't remember). Obviously, i don't like having 240v on the mount outside potentially in wet conditions so I was considering using a 12v-240v inverter as per Christian Buil's recent posts, but stumbled on the EL wire inverters. The series resistor prevents the bimetallic strip switch in the calibration lamp from switching off.

It works fine and no series resistor seems to be required as the current seems to be sufficiently low to not activate the bimetallic strip.

Output voltage of this EL driver is 120V AC when running from 2xAA 1.2V NiMh cells. Rated load on the label of the inverter is 150mA @3v DC. my multimeter measures 14kHz as the frequency but I need to recheck this with an oscilliscope as am not certain about the frequency range of the meter. I was not able to measure the AC current through the glow tube, I guess because my meter isn't able to measure current at such high frequency.

Given that I normally use the calibration lamp for only a few minutes per night, I may not even bother wiring it up to a power supply, in order to avoid the potential injecting 14khz ripple back into other equipment which may not like that sort of disturbance.

So, low cost, intrinsically safe driver for glow starter tubes, and no series resistor required, what's not to like?

[Tom Love]

This is really useful, thanks Hamish.

[Rainer Ehlert]

Hi Hamish,
Interesting. What is your main power voltage in your house ?

110V or 220V ?

I ask because at 120V AC all my starter lamps blow up, but I use them without the capacitor. My starter lamps glow at a voltage of about 75V which I get using a resistor.

[Hamish Barker]

mains power in new zealand is 240v 50 hz.

but the AA-battery powered micro inverter outputs about 120v at very high frequency, circa 15kHz.

I successfully installed it on the spectrograph and used it a couple of nights ago.

if you remove the capacitor you will probably be emitting some broadband RF which may cause interference, although the tiny size of the glow starter means that it can probably not radiate much below 3 to 5 GHz.

[Rainer Ehlert]

mains power in new zealand is 240v 50 hz.

but the AA-battery powered micro inverter outputs about 120v at very high frequency, circa 15kHz.

I successfully installed it on the spectrograph and used it a couple of nights ago.

if you remove the capacitor you will probably be emitting some broadband RF which may cause interference, although the tiny size of the glow starter means that it can probably not radiate much below 3 to 5 GHz.

Hi Hamish,

That answers my question as your starter lamps are for 240V and so 120 Volt does not blow them up.

Thanks Rainer

[Hamish Barker]

I guess you could try running two lamps in series.

[Robin Leadbeater]

It is the current flow once the arc is struck that causes the starter contacts to close so a series resistor might allow it to work on 120v. Alternatively would the inverter run at a lower voltage with one AA battery?

I used the flash circuit from a disposable camera with a 240v RELCO starter
http://www.marcellocucchi.altervista.or ... nlamp.html
Here is my version

dispcam_relco_diffused.jpg (108.96 KiB) Viewed 4446 times

Cheers
Robin

[Hamish Barker]

I tried various series resistors but ithey seemed to disturb the tuning of the oscillator and the arc wouldn't strike. the lamp was most stable with no series resistor and fresh alkaline cells. Nimh cell voltage was too low to get an arc.

I'm interested to see what the performance of the 12v version is, when it arrives.

[Peter Williams]

Thank you very much for this suggestion. I am in North America and the transformer specified for the calibrex project is very difficult to find. I was able to use the existing circuit to turn on the EL “inverter” and the modifications to the program were very straightforward

Happy to share details if anyone is interested

Peter