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GE SSL-6 Silicon Carbide Yellow LED |
GE's 'SSL' range was preceded by the 'LED' series, based on its 1962 laser diode achievements. As early as 1964 it offered GaAs infrared and GaAsP red lasers and LEDs, with astronomical prices as high as $2600 each. These all had the drawback that significant light emission was only produced at sub-zero temperatures, typically rated for operation at 77K. It was not until 1967 that types offering useful output at room temperature were added - but even they appeared pitifully dim due to their peak wavelength being in the deep red at the edge of the human eye's sensitivy.
When the SSL-1 & 6 were launched they were the world's brightest LEDs, due to their silicon carbide chips producing a more visible yellow light whose efficacy rises at higher temperatures - although still very weak. Despite this limitation they found applications requiring long life, high robustness, low current draw, or the possibility to modulate the light at up to 1MHz - all impossible with filament lamps. The 1mm² boron-doped SiC chip is soldered to a TO-18 gold plated kovar transistor header, current being delivered via a gold wirebond at its top surface. SiC LEDs were produced only briefly, and were discontinued before 1970 following the introduction of brighter GaAsP red emitting LEDs such as the Monsanto MV-1 of 1968, and GE's GaP SSL-22 of 1970.
| Manufacturer: | General Electric USA | |
| Lamp Power: | 0.18 Watts | |
| Lamp Voltage: | 3.50 Volts | |
| Lamp Current: | 0.050 Amps | 0.075A maximum |
| Cap Type: | G2.54 Au plated wires | 0.0175" dia. x 1" length |
| Bulb Type: | TO-18 transistor header | |
| Bulb Finish: | Glass lens | |
| Luminous Flux: | ||
| Luminous Efficacy: | ||
| Surface Luminance: | 137 cd/m² | 40 foot-lamberts |
| Beam Distribution: | 18° | to half-peak |
| Colour Temperature & CRI: | CCT: 2870K | CRI: Ra 50 |
| Chromaticity Co-ordinates: | CCx: 0.492 | CCy: 0.496 |
| Peak Wavelength: | 590nm | 80nm half-width to 70.7% of peak |
| Dominant Wavelength: | 578nm | 97% spectral purity |
| Lifetime: | Indenfinitely long | |
| Warm-up & Re-strike Time: | <100 microseconds | to ⅔ peak brightness |
| Burning Position: | Universal | |
| Overall Length: | 6.0 mm | 0.235" (without leads) |
| Factory: | Nela Park | Cleveland, USA |
| Date of Manufacture: | 1968-1969 | |
| Original Value: | US $9.50 (1967) | |
