New LEDs

Blue, Green, Yellow, Orange and Red LEDs

This page documents four new colours of LED for the TB-303/Devil Fish. This is also relevant for the TR-606, and no-doubt the TR-808. Please read the notes below on the different LEDs, since the picture above cannot convey their true brightness or appearance.
There are two sets of doco here. Firstly for users who are considering having me install new LEDs and secondly for those with a technical interest in the LEDs themselves.

Five kinds of LED are shown above. (The image is optimised for CRT monitors - LCD monitors have different brightness curves and are unreliable and lacking contrast in high-lights and low-lights.) All these LEDs are diffused (milky), rather than with a clear (watery) encapsulation. In all cases, the diffused epoxy resin of the LED is the same colour as the LED's light.

C and F#: Original LEDs These are relatively dim, reasonably wide-angle and not particularly even in their illumination pattern. (By "illumination pattern" I means the disc of light which the LED presents when we look at it. At some viewing angles or even when viewed from straight ahead, the light does not form an even disc. This could be due to the LED chip not being centred properly in the package, or because of other factors. )

C#: Red These are very slightly more orange than the original LEDs, but are still pure red. Advantages include:

Very much brighter than the original LEDs.

Very wide angle – so they can be seen from any angle.

Even pattern of illumination within the LED, in contrast to the somewhat varied pattern of the originals.

The non-illuminated colour is a darker red than the originals, which gives greater contrast between on and off states.

D: Orange These are brighter than the originals, have a wider and more even illumination pattern and are fiery orange.

D#: Yellow Nice yellow colour. Like the Orange and Green, these are significantly brighter than the originals and have a wide and even pattern of illumination. Diffusion is a rather lightish yellow colour.

E: Green This is the yellowish-green typical of most LEDs. I cannot find "pure" green LEDs which are suitable for this application. Virtually every green LED on electronic equipment is this somewhat yellowish-green colour. The diffusion is a very pale green.

F: Deep Blue These are a beautiful true blue colour. Viewed with a diffraction grating, their spectrum can be seen to contain only slight traces of green and yellow light, and a prominent violet component, which is really special for a LED. The diffusion of these LEDs is minimal and faintly blue. They are not as wide a beam as the other new LEDs which have a stronger diffusion in their packaging. Like the new Red LEDs, they are very bright compared to the original – but they are not excessively bright. (One person reported eyestrain after an intense all night programming session, and one person found them too bright and wanted another colour instead, but everyone else is really happy with them.) Most blue LEDs have a greater green component, and are consequently more of an aqua colour, but these particular LEDs are a pure and beautiful blue, with a touch of violet.

For purely functional purposes, such as making sure the LEDs are visible at wide angles in intense light, both the new Red and Deep Blue LEDs would be ideal. The other three colours are still a big improvement in brightness on the original LEDs, but the new Red and Deep Blue are brighter still.
You can choose any combination of colours if you like. Pricing is all the same.

I generally recommend all Deep Blue LEDs apart from a new RED LED for the Run/Stop function. This balances with the three Red LEDs in the Devil Fish panel on the upper left.

Technical details

This is for technicians who are interested in installing LEDs in the TB-303 and other items of equipment. I do not recommend that this be undertaken by inexperienced people. Desoldering LEDs is non-trivial. Soldering in the new ones in exactly the right place is very tricky – Ceri and I have a special technique which is hard to explain.
The requirements of LEDs in this application are:

3mm package. (Many LEDs are 5mm, or in some other type of package.)

Diffused. (To disperse the light widely and evenly to ensure they are visible from all angles.)

Bright enough with the particular drive situation in the TB-303 to be visible, and to be significantly brighter than the original LEDs. Increasing the drive current would involve altering the drive circuitry – which would be complex and would involve drawing extra power from the internal supply Such changes may lead to interference with the audio circuitry.

Not too bright, as are some hyper-bright LEDs such as normal blue LEDs. To alter the various drive circuits so they provided less current would be tricky. There are two totally different and independent sets of circuits, plus the Run/Stop LED, so three sets of things to alter.

The package should have a flange wide enough not to let the LED protrude through the front-panel hole, but not so wide as to get in the way with the top row of holes in the TB-303, which are close to the edge of the plastic case. (Our new mounting techniques means this doesn't matter - and some of the LEDs we use do no meet this requirement.

The following information includes the type of LEDs I chose, and some alternatives I also found.
Please do not pester me for more information, or "I don't know anything about electronics but please tell me how to . . . ".

I do not supply LEDs, except as a spare part for a Devil Fish.

I will not install ultra-violet LEDs. My view of these is that they are very bright, but just beyond the visible range so that if they were installed you would be looking into them continually, with irises wide open, and exposing your retina to a very bright light without realising it.

This page contains virtually everything I know about LEDs for this application, and part of the reason for writing it is so that I can refer to it in the future. Another reason is to answer people's questions so they don't have to ask me time and again! Please let me know any corrections or suggestions for improvements.

There is a very extensive web site on LEDs: http://ledmuseum.home.att.net . Don Klipstein's site http://www.misty.com/~don/is a treasure trove of information too. Be sure to read the two documents there on LEDs and on super-bright LEDs.

Kingbright LEDs can be obtained from distributors, in my case http://www.tenrod.com.au/. See the Kingbright web site: http://www.kingbright.com . They package other manufacturer's chips.

Although I am not installing them, Nichia make some exquisite hyper-bright LEDs. Their web site is: http://www.nichia.com and they can be obtained from distributors such as Tenrod. Toshiba also make hyper-bright LEDs. The Hewlett Packard LED site is: http://www.semiconductor.agilent.com/led/genpurpose.html .

The Deep Blue LEDs are Kingbright, from Tenrod. The other LEDs I obtained from Farnell Electronic Components, who have branches in many countries: http://www.farnell.com/

General information on electronic parts manufacturers and distributors can be found at http://www.electronet.com and various other sites.

Deep Blue LEDs

These are Kingbright L934 MBD. (Not L935 as I previous had here!) They are a very distinctive and beautiful LED. As noted above, these are a pure blue with a touch of violet, in contrast to the typical greenish blue, or aqua of hyper-bright blue LEDs, such as those from Nichia.
I don't know any comparable device, nor have I looked hard for other 3mm diffused blue LEDs.

New Red LEDs

There are probably dozens of sufficiently bright, but not hyper-bright, 3mm diffused LEDs. I chose HP's LED: HLMP-1700. Farnell part number 322-556.

New Orange LEDs

I chose Vishay TLH04400 . Farnell part number 656-550. Other contenders were:

LED Technology L08R3000F1. (Farnell part number 178-307.

HP HLMPK401, RS Components part number 826-616.

New Yellow LEDs

I chose Multicomp's L-934 LYD. This part number is very similar to a Kingbright part number. Farnell part number 637-063. Other contenders were:

HLMP 1719 – seems to be identical.

HLMP 1401. Very similar, but the diffusion is more orange.

Siemens / Infineon LY3366-PS. (Farnell part number 881-790.) A very bright diffused yellow LED which is perhaps fractionally redder than the above. I judge this to be too bright for the TB-303, but it is a beautiful LED.

New Green LEDs

I chose Multicomp L-934 LGD. Farnell part number 637-051. This is the typical 565 nm colour of most "green" LEDs, which I consider to be a yellowish green. Other contenders were:

Vishay TLH64405. Very similar, with darker diffusion (which is think is better, for greater contrast) but the flange was a little slim and they tended to go straight through the TB-303 front panel holes.

There are some "Emerald Green" LEDs from Hewlett Packard, such as the 558nm HLMPK600. This is undiffused 3mm, and is barely bright enough. If there is a diffused version, I predict it would not be bright enough. This "emerald green" is halfway between the standard "yellowish-green" of most green LEDs and what I think is a "pure-green", as described below.

Kingbright make a 3mm diffused "pure-green" LED (L-934PGD) with a peak intensity wavelength of 555 nm. Unfortunately it is too diim.

I have a sample of a beautiful pure-green LED from Toyoda Gosei http://www.toyoda-gosei.co.jp/led/e-index.html : the E1L51-3G. This is a hyper-bright green LED and its peak wavelength is 520 to 530 nm, which is is a touch shorter (bluer) than the L-934PGD. It is seriously bright! If it was available in 3mm diffused, and if the electronics were modified to reduce the drive current, this would make a really beautiful pure green LED.

There are some other possible LEDs, such as the "white" LEDs manufactured by Nichia and others. These are a hyper-bright blue (aqua or greenish blue by my reckoning) LED chip surrounded by a yellow phosphor. They are a very "cold" white, with no real red components in the light. They are damn-bright and are probably too bright for a TB-303 / Devil Fish unless the drive electronics was modified for lower current . . . . unless you really want to wear welding goggles or sunglasses whenever you are using it.

Update history

2000 March 22: page established.
2003 April 24: mentioned UV LEDs and the Red Run/Stop.

C and F#: Original LEDs	These are relatively dim, reasonably wide-angle and not particularly even in their illumination pattern. (By "illumination pattern" I means the disc of light which the LED presents when we look at it. At some viewing angles or even when viewed from straight ahead, the light does not form an even disc. This could be due to the LED chip not being centred properly in the package, or because of other factors. )
C#: Red	These are very slightly more orange than the original LEDs, but are still pure red. Advantages include: Very much brighter than the original LEDs. Very wide angle – so they can be seen from any angle. Even pattern of illumination within the LED, in contrast to the somewhat varied pattern of the originals. The non-illuminated colour is a darker red than the originals, which gives greater contrast between on and off states.
D: Orange	These are brighter than the originals, have a wider and more even illumination pattern and are fiery orange.
D#: Yellow	Nice yellow colour. Like the Orange and Green, these are significantly brighter than the originals and have a wide and even pattern of illumination. Diffusion is a rather lightish yellow colour.
E: Green	This is the yellowish-green typical of most LEDs. I cannot find "pure" green LEDs which are suitable for this application. Virtually every green LED on electronic equipment is this somewhat yellowish-green colour. The diffusion is a very pale green.
F: Deep Blue	These are a beautiful true blue colour. Viewed with a diffraction grating, their spectrum can be seen to contain only slight traces of green and yellow light, and a prominent violet component, which is really special for a LED. The diffusion of these LEDs is minimal and faintly blue. They are not as wide a beam as the other new LEDs which have a stronger diffusion in their packaging. Like the new Red LEDs, they are very bright compared to the original – but they are not excessively bright. (One person reported eyestrain after an intense all night programming session, and one person found them too bright and wanted another colour instead, but everyone else is really happy with them.) Most blue LEDs have a greater green component, and are consequently more of an aqua colour, but these particular LEDs are a pure and beautiful blue, with a touch of violet.