DESIGN AND IMPLEMENTATION OF COMPARATOR CIRCUIT MODEL USED AT AUTOMATIC ADJUSTING SYSTEMS WHICH EQUIP SPRINKLING MACHINERY
Mihnea Glodeanu, Tudor Alexandru, Simion Popescu · 2012
The most important demand imposed for sprinkling treatments is to ensure the stability of liquid rate. That is the reason for what the sprinklers are fitting out with automatic adjusting systems, in order to automatize the working process. Such system cannot work without an adequate comparator circuit. The paper presents the constructive and functional analysis of a comparator circuit, used for speed and flow signals. In the block scheme of electronic equipment for automatic adjustment of liquid flow with displacement velocity, the comparator circuit is designed to process information presented in the form of input voltages and output generating commands to be applied to the electric motor (that drives the fluid flow control valve). The flow control valve is electrically operated and must be driven in both directions, so that the comparator circuit will generate two separate commands in the form of electrical signals. These electrical signals are amplified by the power amplifier of the equipment, at an adequate level to drive the motor. For designing such a circuit, first it is necessary to establish the proper transfer functions, for command and stationary processes. Based on transfer functions an experimental model of a comparator circuit was carried out. To verify the functionality of the circuit in laboratory conditions two signal generators were used, mounted at the inputs of the speed transducer, respectively liquid flow transducer. Each generator ensures an rectangular signal, with frequencies belonging to the work domain of the transducers. From the data base analysis and the obtained results it has been ascertained that the comparator circuit works in concordance with the specific transfer functions, for those two distinct operating modes (transitive and stationary).