A lamp circuit of a light emitting device adapted to be directly installed in a lamp holder of a conventional fluorescent lamp having an electrical ballast with a resonance circuit, the resonance circuit comprising a ballast capacitor and an inductor, the lamp holder having a first lamp contact and a second lamp contact, the lamp circuit of a light emitting device comprising: a rectification unit adapted to be connected between the first lamp contact and the second lamp contact, the rectification unit adapted to receive an alternate current voltage transmitted by the lamp holder and to rectify the alternate current voltage so as generate a direct current voltage; a current limiting unit connected to the rectification unit, and adapted to generate a direct current corresponding to the direct current voltage; and a light emitting device connected between the current limiting unit and the rectification unit, and adapted to generate light corresponding to the direct current, characterized in that the lamp circuit of a light emitting device further comprises a capacitor having two capacitor contacts and adapted to be connected between the first lamp contact and the second lamp contact such that the capacitor is with one of its two capacitor contacts electrically connected to the first lamp contact and with the other capacitor contact electrically connected to the second lamp contact, the capacitor thereby being connected in parallel to the ballast capacitor, said capacitor of the lamp circuit of a light emitting device being adapted to reduce, when connected in parallel to the ballast capacitor, the resonant frequency of the resonance circuit (410, 412) of the electrical ballast in a way that an operation frequency of the lamp circuit does not overlap with an operation frequency of the electrical ballast. a rectification unit adapted to be connected between the first lamp contact and the second lamp contact, the rectification unit adapted to receive an alternate current voltage transmitted by the lamp holder and to rectify the alternate current voltage so as generate a direct current voltage; a current limiting unit connected to the rectification unit, and adapted to generate a direct current corresponding to the direct current voltage; and a light emitting device connected between the current limiting unit and the rectification unit, and adapted to generate light corresponding to the direct current, characterized in that the lamp circuit of a light emitting device further comprises a capacitor having two capacitor contacts and adapted to be connected between the first lamp contact and the second lamp contact such that the capacitor is with one of its two capacitor contacts electrically connected to the first lamp contact and with the other capacitor contact electrically connected to the second lamp contact, the capacitor thereby being connected in parallel to the ballast capacitor, said capacitor of the lamp circuit of a light emitting device being adapted to reduce, when connected in parallel to the ballast capacitor, the resonant frequency of the resonance circuit (410, 412) of the electrical ballast in a way that an operation frequency of the lamp circuit does not overlap with an operation frequency of the electrical ballast.