Desk Lamp Debate

[peter]

Over the last few years, there has been a noticable trend towards using LED desk lamps (goosenecks) with control products, moving away from traditional tungsten lamps. This trend has also been helped by an ever increasing array of LED lamps becoming available from the far east at low cost.

 

LED desk lamps can be polarity sensitive if a rectifier is not incorporated into the lamp design. Tungsten lamps happily work on AC or either DC polarity, and hence until now the socket wiring has not been an issue. However with the increase in the use of LED lamps, compatibility issues between consoles and lamps are becoming more frequent (e.g. this topic).

 

We (Cooper Controls / Zero 88) have been carrying out a survey of consoles to try and establish if there is a convention for this pinout, particularly the XLR3 pinout (XLR4 tends to be used for lamps on sound equipment, XLR3 for lamps on lighting equipment) and it turns out that there seems to be a number of pinouts available on different control consoles.

 

The Pinout that Zero 88 currently use is:

 

Pin 1 Not Connected

Pin 2 0V

Pin 3 12V

 

We would like to gather concensus across the main consoles of the industry as to what (if any) standard polarity and pinouts are used. If your console hasn't been listed in this thread already, it would be greatly appreciated if you could carry out a simple metering of the XLR3 desk lamp socket on your console and post the results here. Likewise if you have an LED desk lamp which you are using, post the brand and model, and the pinout used. The more information we can gather, the better for all concerned.

 

Many thanks for your time and effort

 

 

 

Peter Kirkup

 

Product Manager

Cooper Controls - Zero 88

[The Gaffa]

ETC appears to be:

 

Pin 1 Ground

Pin 2 0v

Pin 3 12v

 

(ETC Express 250 & 24 / 48) as supplied

[Brian]

Stairville 12 (Thomann 180231) LED lamp

 

Pins 1 and 3 joined and 0v

Pin 2 +12 v

[dbuckley]

Littlite do a catalog which cross references their lights to various pieces of equipment.

 

I think its fair to say that desk lamp connections are standardised, much like RS232 is standardised <_<

[Tomo]

The other thread actually has more information...

 

The 'convention' is:

Pin 2: 0v

Pin 3: 12vdc

 

Pin 1 may be either N/C or Chassis Earth.

N/C is better, as it prevents damage in the case of mis-wired lights.

 

The shell is generally Chassis (PE or RF) Earth, mostly because it's hard not to be.

 

Issues arise when the stick light uses the shell for the return path - I think these were designed for some of the cheaper sound consoles.

[stillwave]

Stairville 12 (Thomann 180231) LED lamp

 

Pins 1 and 3 joined and 0v

Pin 2 +12 v

 

We have a Bull Frog & the Stairville LED gooseneck lamps... just a quick job on the soldering iron sorted the pinout, obviously as you say a general consensus (this wouldn't be a viable option with a different desk every day!).

 

having said that, most lamps that I've seen seem to live with the desk for their life (house lx, touring lx & sound desks)

[blackbird]

I think I am correct in saying that at Stage Tech we use the 'standard' pinout, which is what the branded LED Littlelites come as:

 

Pin 1 Not Connected

Pin 2 0V

Pin 3 12V

 

However ... I recently had two Littlelites in the same batch which behaved completely differently. I think one was probably faulty, but basically its behaviour was the inverse of expected - bright when it should be dim etc, and the base was getting rather warm! I assumed the pinout was just the wrong way around for some odd reason, but on taking it apart the circuitry was completely different, and swapping the legs didn't help. Given up as a lost cause with no time to diagnose, but rather strange to come like that from the mfr.

 

The other question is whether to use a PWM to give smooth LED dimming or not ...

[JDP]

What about the desk lamps on 4 pin?