Constant-current diode

Abstract: An LED driving circuit is provided for making it possible to economically drive a serially connected LED circuit by means of a switching device with a relatively low withstanding voltage even if the number of serially connected LED devices increases. In an LED driving circuit provided with a serially connected LED circuit ( 11 ) in which many LED devices are serially connected and a switching device ( 13 ) serially connected with the serially connected LED circuit ( 11 ) to control that an electrical current flowing through the serially connected LED circuit ( 11 ) is turned on or off, wherein a circuit device ( 15 ), which comprises a resistor, a constant voltage diode, a constant current diode, or the like, is connected in parallel with the switching device to make a minute current flow through the serially connected LED circuit ( 11 ) to the extent that the LED devices are not turned on when the switching device is turned off.

Abstract: An indicator circuit for indicating the states of various electric components such as limit switches, comprising a light emitting device such as a light emitting diode, and a constant current device, such as a constant current diode, connected in series with the light emitting element The constant current element significantly expands the operable range of the input voltage to the indicator circuit, and keeps the brightness of the light emitting device constant over a wide input voltage range For high voltage applications, a plurality of constant current devices may be connected in series, and, preferably, balancing resistors and/or zener diodes may be connected in parallel with them

Abstract: VHF cascode amplifier having a PIN diode in series with its input. The RF impedance of the PIN diode varies inversely with the DC current through it. A constant DC current source including a constant current diode supplies DC current to the PIN diode. A bypass transistor has its collector connected to the constant current source and its base coupled to the amplifier output. Variations in the peak amplitude of the amplifier output cause variations in the current flow through the bypass transistor. The resulting change in DC current flow in the PIN diode changes its RF impedance so as to overcome the change in the amplifier output and maintain the output level constant.

Abstract: PURPOSE:To avoid variation of the luminance of a light emitting diode induced by the influence of fluctuation of a voltage or the like by connecting a constant current diode to the light emitting diode in series. CONSTITUTION:A constant current diode D1 and a light emitting diode D3 are connected in series from a source to a ground and, moreover, a correcting resistance r1 for compensating the effect of self-heating of the constant current diode D1 is provided in parallel. Therefore, as the current determined by the constant current diode D1 flows regardless of the fluctuation of the source voltage VCC, stable light emission can be obtained by the light emitting diode D3. When the current is larger than 1mA, if the device is operated by the high voltage VCC, the current is reduced by the self-heating of the diode D1. If a correction resistance r1 is provided to correct this deviation, the current can be compensated completely. By employing a simple circuit constitution in which the constant current diode is connected to the light emitting diode, the light emitting diode can be driven by a stable constant current regardless of the fluctuation of the source voltage so that the constant luminance can be obtained.