In a flash circuit for a single use camera, a minimum residual charge voltage level is maintained on a flash capacitor to ensure availability of an energy source to operate an auxiliary circuit, such as an optical data recording circuit, even after prolonged periods of non-use of the camera. This minimum charge voltage level is maintained by provision of a DC circuit path from the camera battery via the charger circuit and flash power rectifier diode to the flash capacitor. Automatic restart of the flash charging circuit upon closing of the flash trigger switch is assured by connecting the charging circuit start terminal to the trigger switch by means of a normally reverse biased re-start diode that isolates the start terminal from the flash capacitor voltage on the trigger circuit at all times when the flash trigger switch is open. To avoid inadvertent start up of the flash charger during camera assembly when the battery is installed, an assembly process employs precharging of the flash capacitor to maintain the re-start diode in reverse biased mode during the assembly process.