We developed a number of LED drivers based on fast blue and UV LEDs. The drivers are inexpensive, robust and simple in operation. They can imitate well Cherenkov and scintillation light pulses. The drivers can be used for calibration purposes in Cherenkov and scintillation detectors. For Cherenkov detectors the fastest LED drivers are used, their light pulses width is less than 1 ns (fwhm) and light yields can be adjusted in a wide range with maximum close to 10^9 photons per pulse. They can imitate single passage of single relativistic particles and/or showers. In case of scintillation detectors, special drivers were developed with their light pulses shapes imitating well light pulses of plastic, liquid and even inorganic scintillation detectors. Moreover it is possible to select drivers which can repeat well pulses of any particular scintillation detectors. It is believed that the developed drivers will be useful for tuning, control and calibration of experiments using Cherenkov and scintillation detectors.