| 摘要 |
The circuit includes two groups (1,2) of LEDs (3). The group (1) has the LEDs preceding a series resistor (R2) and group (2) is preceded by a series resistor (R3). The two groups of LEDs are bridged together at points (5,6) by a forward biassed diode (4). The voltage supply is typically 0-28 V. At low supply voltages, the leds operate in parallel. When the potential difference across the diode (4) passes the bias threshold, all the leds are placed in series. The change in intensity with voltage enables the array to follow the graph for a filament lamp by suitable choice of resistance (R1, R2, R3). <IMAGE> |
