Control circuit for water flow heater - limits number of switching steps by disconnecting for limited time period after given number of switching steps

摘要

The control circuit for a flow heater reduces the frequency with which the heating element is switched. After the heating element has been switched a given number of times in a given period of time it is switched off for a preset time period. At the end of this time it is switched on again and the cycle is repeated. The switchings on are converted into pulses by a detector circuit which are counted. The counter is cleared by a clock after the given time has elapsed. The counter contents are compared with a reference and the result used to operate the disconnecting switch.