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Discussion Starter #1
Goo day all.
I have a quick question (hopefully)

I am trying to build a monochromatic light source box and would like to use a Low pressure sodium lamp for it. I have an 18 watt T15 lamp, this one:
Philips 234047 18-watt T15 SOX-E18 Low Pressure Sodium HID Light Bulb

I also have Fulham workhorse ballast - MODEL: WH2-120-C

The problem is that I cant find any reference to power specs for a T15 lamps in the technical write up for WH2-120-C.

Will this combination work or do i need a different ballast? If a different ballast, which one? Amazon link would be super appreciated.

This is for a monochromatic viewing box; so will have it on for may be an hour or 2 at a time, couple times a week. Not a "24x7 uptime" type of install.

New to sodium lamps... trying not to blow things up...

Thanks ahead
 

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The WH2 isn't intended for LPS lamps but it will start and run an 18 Watt lamp just fine. Connect both red ballast leads to one pin of the lamp, the yellow lead to the other pin.

This is for a monochromatic viewing box; so will have it on for may be an hour or 2 at a time, couple times a week. Not a "24x7 uptime" type of install.
Is this typically what these setups are used for? There have been a number of people on various DIY boards asking about this specific combination (the WH2 and low pressure sodium lamp) the last few years and I'm curious what people are doing with them.
 

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Discussion Starter #3
The WH2 isn't intended for LPS lamps but it will start and run an 18 Watt lamp just fine. Connect both red ballast leads to one pin of the lamp, the yellow lead to the other pin.



Is this typically what these setups are used for? There have been a number of people on various DIY boards asking about this specific combination (the WH2 and low pressure sodium lamp) the last few years and I'm curious what people are doing with them.
Thank you for the feedback.

The LPS lamps have a very narrow colour spectrum, which is why HPS lamps were invented to help reproducing colours more accurately. Due to very narrow spectrum of LPS it can be used as a monochromatic light source. In theory a laser pointer can do the same thing, but you do not want a focused light, you want dispersed monochromatic light. This is why LPS sodium lamps are popular for this purpose.

In machining and metrology one can use monochromatic light to study the distance between two suraces, the light reflects from both with certain amount of phase shift and produces interference patters (kind of like diffraction of waves). Non-monochromatic light won't produce as clear of a pattern and may not produce a visible pattern at all.
 

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Discussion Starter #4
A quick follow-up question:
I connected the light to the ballast, it powers up and seems to work; however it appears much dimmer than what an 1800 lumen output I’d expect to be. 1800 lumen is about what a 100W incandescent bulb outputs. The output i am getting from this 18W LPS light is comparable to may be a 40W incandescent.

This is after 35 minutes of being on.
Do i need a bigger ballast? Or is it the colour spectrum that is messing with my eyes and brightness gauging?

Just want to make sure this is not an indication of a problem.

Thanks ahead
 

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If the lamp isn't mounted in a grounded metallic enclosure you might need to give it some help starting. Try holding a metal ruler or similar metal object parallel to the lamp and about 1/2" away. Did it start and get much brighter?
 

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If the lamp isn't mounted in a grounded metallic enclosure you might need to give it some help starting. Try holding a metal ruler or similar metal object parallel to the lamp and about 1/2" away. Did it start and get much brighter?

The ruler trick did not increase the power ( i actually used a 3/8th inch steel rod instead of the ruler)

Do sodium lamps require metal case to get inductively coupled to or is case grounding the load as well as the lamp socket enough? This will determine the construction materials for the light box; I was not planning on using a metal box...
 

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The ruler trick did not increase the power ( i actually used a 3/8th inch steel rod instead of the ruler)
Maybe it is started, then. I was assuming it was not. Are you getting a solid white(ish) light output or is it more of a purple/blue?

Do sodium lamps require metal case to get inductively coupled to or is case grounding the load as well as the lamp socket enough?
Normally they do not. But a LPS HID ballast is normally used and they are capable of initiating a much more powerful pulse to start the arc in the lamp. Using a grounded metal case or using the metal rod allows a weaker fluorescent ballast to start the arc if it's having trouble.
 
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