Engine Gauge Lights

[karista]

My fuel gauge light appears to have a defective Twist socket. Its the original Catalina OEM Engine Panel so I assume these are Teleflex gauges. Does anyone know the Socket Twist part # or are these T10 Twist Locks?

[Ron Hill]

Benrd : I wrote a Mainsheet tech note article (years ago) where I pointed out that the standard #194 light bulbs in the Teleflex instruments were TOO HOT for that application!!!  I recommended that owners switch to a cool LED bulb and gave some LED Superbright numbers. 

I found that a strip of Bamboo would wedge the new LED bulb in the old (holder) in place so it light up the instrument.  A new holder can be purchased from auto parts dealer, but the screw up is on the instrument body itself.   I further recommended that the LED be a RED LED so it didn't mess up your night vision!!   

A few thoughts

[KWKloeber]

Half my OEM gauges have a (silicone?) amber sock over the bulb which obviously also softens the brightness - Ron do you have a part number for (not too bright) red or amber LED bulbs? 

BTW, MarineBeam tells me that blue is the new red and is better at preserving night vision.
I picked out new dimming overhead fixtures (white/blue-night) for throughout the cabin of a J/120 and the owner LOVED them.

[waughoo]

Marinebeam males really great stuff.  I have spent some time talking to the owner about their gear.  I installed their LED Coast Guard NAV nights and I am a fan.

[glennd3]

I replaced my gauges last year as they were broken at the light socket. They are about 25 bucks a piece from Defender. I also did red led lights.

[Ron Hill]

Ken & Guys : Just go to SuperbrightLEDs and type in 194 LED and you'll get 5 different colors to choose from they are about $2.50 each 300? lumens

A few thoughts  -  great stuff in the old Mainsheet tech notes !!!   

[Jim Hardesty]

To second Ron,  I bought all my replacement led bulbs for the cabin from SuperbrightLED.  Didn't need to change any fixtures and am very happy with them.  And I think they were very well priced.
Jim

[karista]

Ron
Will these LED's fit the twist sockets in the standard Teleflex Engine gauges? You mentioned earlier that you needed to install a Bamboo strip to hold them in place? Do you know the type of twist socket or P/N that are in these original Teleflex gauges?

Ken & Guys : Just go to SuperbrightLEDs and type in 194 LED and you'll get 5 different colors to choose from they are about $2.50 each 300? lumens

A few thoughts  -  great stuff in the old Mainsheet tech note

[Ron Hill]

Benrd : The 194 LEDs will "stab" into the twist holder.  I got new twist holders from the Ford dealer.

The bamboo strip was to keep the twist holder in place, because the over heated plastic on the gage case had melted/broken!!  clear as mud?

Ken : The new aircraft night lighting is Green, like the night illumination in the new autos!!

A few thoughts

[Catalina007]

I bought  these Sierra gauges  which are a close match and work great
https://www.amazon.com/gp/product/B000FQ1T5O/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

[tmac]

I couldn't help but notice the recommendations for blue or green lighting.  I've benefitted from the combined wisdom on this site for some time, and would like to contribute something back in the form of some concrete science in the area of night vision, and put to rest the urban myth of blue or green being the new night vision color.
I apologize in advance for the length, but I tried to be complete.

Night Vision Lighting discussion
The recent promotion of green light to protect your "night vision" is a modern myth. Since the light detecting pigment in the Rods are so sensitive to green light, green readily destroys your natural adaptation to darkness.  I realize that the paper charts we use can be hard to read in red light, and using green or green-blue light helps in this regard, but that is an entirely different discussion.

In the anatomy of the eye, the retina is made up of two types of receptors:  Rods and Cones.  Cones are your daylight receptors.  Your Rods in your retina are most sensitive to dim light, providing your night vision. Rods use a light sensitive chemical called rhodopsin to detect the light.  The rhodopsin "bleaches" or breaks down when struck with light - it's this breakdown that is detected by the nerves and that makes you "see" the light. The more rhodopsin that builds up in the rods, the better you can see really dim lights. It takes up to an hour to build up a full complement of rhodopsin. Even starlight causes the bleaching (when you look at the stars, you detect it, hence the breakdown is occurring), but the rhodopsin builds back up easily since there was so little breakdown from such a dim light source.

A bright light in the detection frequency of rhodopsin instantly breaks down the rhodopsin that has built up - it's really sensitive stuff. Rhodopsin's detection frequency goes up to about 610nm (light reds or orange reds) so light in this color range will still diminish your night adaptation by bleaching the rhodopsin in the rods. Dark red (>650nm) is above this frequency, so your rods can't "see" dark red light. 

The effect where you turn on a BRIGHT red light and it seems to kill your vision is actually the red Cones getting shocked (not the rods) because you are going from a completely dark environment to a bright red environment. As a result, you'll see afterimages from the bright red light bleaching the pigments in your red cones, sort of like what happens when to look at a sun lit scene after being in an office all day and then go back into the office. You can't see well at all.  The red cone visual field overlaps the rods and makes it harder for your brain to distinguish the difference between the two when the red cone field is full of afterimages. This is why a dim red light is recommended - not because bright red light compromises your rod-based night vision, but because it affects the red cones so profoundly that you perceive the afterimages as overlapping your rod's field of view. Bright green light would do the same, but it would also bleach the pigments in the rods, destroying your night adaptation completely.

Green light is definitely in the detection frequency of the rods' Rhodopsin and will bleach it right out. Green light will at least partially if not totally cause a loss of your natural "night vision" or "night adaptation" depending on the intensity. You then get to wait for up to an hour for the rhodopsin to build up again. This is all proven via scientific experiments you can research at the library or your local college.

People think green is good for night vision due to their experiences with night vision equipment. This has resulted in the modern myth that green light preserves your natural night vision. This is not true and has resulted in a great deal of non-research-based marketing by people trying to sell green LED lights Devices such as night vision goggles have green displays due to the fact that our eyes are so sensitive to the color green it's far easier to pick out details on a green display than it is any other color. This is important because the displays on most night vision devices are extremely "grainy", and the green color helps to keep details that would be lost with other color displays. The downside to a green display is that since your eyes ARE so sensitive to the color green, when the night vision devices are taken off it takes considerably longer for your eyes to readjust to total darkness than with red light. Green light makes your pupils constrict further since your eyes are so sensitive to this color.

I really think that people are looking for a "new and modern" way to preserve night vision, thinking that red light is the "old fashioned" way. However, our eyes haven't magically evolved over the last 50-100 years to suddenly accept green as a night vision preserving color. If you think about it, this red light/night vision link is really an evolutionary development.  As the sun sets, what is the predominant color you see?  Red!  At this low angle of the sun the shorter wavelengths of the sunlight are refracted away from the atmosphere, leaving only the red end of the spectrum.   Human vision adapted so that night vision would be protected as darkness fell.  It makes perfect sense. Dark red light is your only choice for preserving your natural rod-based night vision due to the anatomy of the eye, and can be used at intensity levels that allow normal functions without night vision loss.

You CAN use a really super dim light of any color - about the brightness of starlight, which will break down rhodopsin slowly enough that it can make up for the breakdown on the fly. However, all the LED products I've seen are way, Way, WAY too bright for this. Plus, the whole idea of using red light is so that it can be bright enough for you to operate pretty much normally without losing your night adaptation. Using a super dim light won't allow anything close to "normal" operation.

If my explanation isn't good enough for you, here's a quote from USAF Flight Surgeon's Guide 

QUOTE:
Enhancing and Maintaining Dark Adaptation: For maximum utilization of scotopic vision, 20 to 30 minutes are required, in total darkness, to attain satisfactory dark adaptation. A more practical alternative is to have the aircrew members wear red goggles to facilitate dark adaptation. Red goggles can be worn in normal illumination and do not interfere significantly with the ability to read maps, charts, manuals, etc. They block all light except red light, and red light does not simulate the rods, as we have seen.

To understand why red filters can be used to achieve dark adaptation, it is necessary to examine the relative positions of the photopic and scotopic sensitivity curves in Figure 8-20. If a red filter with a cutoff at about 650 nanometers is worn, essentially no light is transmitted to the eye that can stimulate the rods. However, the cones are sensitive to the red light, and, thus, adequate visual acuity is permitted. By wearing red goggles for 30 minutes, the rods are almost fully dark adapted. Although the cones are not dark adapted, it only takes about 5 to 7 minutes, after a pilot steps into the dark, for the cones to adapt. Cone adaptation is relatively unimportant since they are incapable of functioning in starlight illumination. There are, however, some drawbacks to wearing red goggles. For example, when reading maps, all markings in red ink on a white background may be invisible. In addition, red light creates or worsens near point blur in the pre-presbyopic or presbyopic pilot, as red light comes to a focus behind the retina and requires more accommodation to bring it into focus.

Dark adaptation of the rods develops rather slowly over a period of 20 to 30 minutes, but it can be lost in a second or two upon exposure to bright lights. The night flyer must, therefore, be taught to avoid bright lights. Also, the instrument panel must be kept illuminated at the lowest level consistent with safe operation, and the flyer must avoid looking at flares, after-burner flames, or gun flashes. If light must be used, it should be as dim as possible and used for the shortest possible period.

Dark adaptation is an independent process in each eye. Even though a bright light may shine in one eye, the other will retain its dark adaptation if it is protected from the light. This is a useful bit of information because a flyer can preserve dark adaptation in one eye by simply closing it.

Cockpit Illumination: The use of red light (wavelength greater than 650 nanometers) for illumination of the cockpit is desirable, because it, like red goggles, does not affect dark adaptation. Red cockpit lighting has been traditional since World War II. The intent was to maintain the greatest rod sensitivity possible, while still providing some illumination for central foveal vision. However, red cockpit lighting did create some near vision problems for the pre-presbyopic and presbyopic aviators. With the increased use of electronic and electro-optical devices for navigation, target detection, and night vision, the importance of the pilot's visual efficiency within the cockpit has increased and new problems have been created. Low intensity, white cockpit lighting is presently used to solve those problems. It affords a more natural visual environment within the aircraft, without degrading the color of objects. Blue-green cockpit lighting is used in aircraft in which night-vision devices are used because, unlike the human eye, these devices are not sensitive to light at that end of the visual spectrum. In addition, blue-green light is the easiest for accommodative focus and is seen by the rods more readily than any other color. It is not seen as blue green, however, but only as light.

END QUOTE

The fact that blue-green lighting is used in aircraft cockpits as highlighted in the last sentence above is probably where the misconception of green or blue green light preserving human night vision comes from.  The night-vision devices they are using require that wavelength.  The big problem here is that lighting manufacturers have latched onto this statement without using their brains and are producing very bright green LED products that they claim will preserve night vision. This claim is patently untrue.

Although the rods are most sensitive to blue-green light, this wavelength light used at an intensity level bright enough to discern the color variations on a nautical chart will bleach out the rhodopsin rapidly and as a result, compromise your night adaptation. That's just the way it works.

Red is the only color to preserve night vision at intensity levels where you can work somewhat normally. Very dim light of any color will be usable without significantly compromising your natural adapted night vision, but if you can "see the color variations" of the light, it's degrading your night vision. The exception is dark red, which the Rods are essentially blind to. The important point here is that you can't operate equipment, write in a notebook, etc., by just starlight, at least not with accuracy. You need a more intense light to see with that won't compromise your night vision when it's shut off - hence the use of red light.

[Jon W]

karista - When replacing my gauge and tach lights to LED, I found that my voltage gauge had a PC 194 assy. You can't replace just the bulb. I found a 194 base socket that fit my newer Teleflex voltage gauge on SuperBrightLEDs.com. The PN is T3.25S-TW: 168/194/921 (T3-1/4) Twist Lock Wedge Base Socket – T3.25 Socket.

I didn't check to see if it fit the older temp and fuel gauges, but it's only a $1.

[Ron Hill]

Guys : I found the new twist-in bulb holders at the Ford dealer parts.  They came with a new #194 bulb which I kept for incandescent #194 spares to use in my auto!!

A thought