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New type of PUT replacement circuit

  

The circuit according to the invention can be advantageously used for supplying pulsed light sources, and in all cases where it is necessary to generate electrical pulses of high efficiency which can be triggered at any time. The increasing complexity of modern electronic devices, especially in the case of battery power supply, requires the use of low-loss circuits. The invention aims to provide a high efficiency pulse generator that produces an output signal with an amplitude approaching the supply voltage at a significantly lower current consumption than conventional generators. A characteristic feature of a pulse generator with a conventional PUT is that the output signal amplitude cannot be raised above the steep voltage level imposed by the internal voltage ratio. A further disadvantage is that a significant quiescent current flows through the low internal conduction resistance even during pulse breaks in the generator. Thus, only a small fraction of the supply energy is used for pulse generation, most of the current is dissipated without being converted into a useful signal. Because of this constant quiescent current, the efficiency of this pulse generator is very low.

The invention is based on the realisation that a PUT replacement circuit, after removal of the internal conduction resistance element, is capable of being designed as a pulse generator to produce pulses that can be triggered at arbitrary times by an external trigger unit. Since, after the above modification, pulse triggering can be generated at any stage of the charging process, an output signal of amplitude approaching the supply voltage can be produced, and the removal of the internal conduction resistance eliminates the shunt current bypassing the charging capacitor, which significantly improves the efficiency of the circuit. With an optimal choice of the values of the sub-elements, the efficiency of the circuit according to the invention is about an order of magnitude higher than that of a pulse generator based on a conventional PUT substitution circuit.

Due to the removal of the conduction resistance, the circuit is also activated by very weak (nanoampere order) trigger signals. At the same time, the internal voltage ratio has been eliminated, which means that the voltage of the charge storage element can now take any value within the supply voltage interval. The circuit according to the invention further extends the programmability of pulse generators based on PUT or PUT replacement circuits. It can be seen from the above that this circuit has a wide range of applications, in addition to supplying pulsed light sources, in all cases where relatively large amplitude pulses with low power loss and low power supply voltage are required.

 

        KUN Ákos

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