GB1111269A - Analogue-digital converter - Google Patents

Abstract

1,111,269. Analogue-to-digital converters. LICENTIA PATENT-VERWALTUNGS G.m.b.H. 23 July, 1965 [24 July, 1964], No. 31455/65. Heading G4H. In an analogue-digital converter, the input voltage is applied to a number of potential dividers, one for each digit of the output signal, each centre point being connected to a threshold device which when operated gives an output signal and causes additional resistors to be switched into the potential dividers of lower order digits. The threshold devices consist of transistors TrO, Tr1, &c. which respond when the voltage becomes zero or positive. The reference voltage + U is ten volts positive and the unknown voltage A is negative. The potential divider for digit 1 consists of resistor RO1 and rO, 1 in the ratio of 1/100. If the unknown voltage is 0À 1 volt or above, transistor TrO will conduct and operate output trigger TO. In parallel with resistor rO,1 are further resistors rO,2, &c., which may be switched into circuit under the control of triggers T1 &c. corresponding to higher digits. The embodiment illustrated is a two-decade, binary-coded decimal system. For an input voltage value of 0À5 volt, for example, the lowest three transistors TrO, Tr1 and Tr2 instantly respond. Trigger T2 switches resistors r1,4 into the " 2 " digit potential divider and rO,4 into the " 1 " digit potential divider. Trigger T1 switches resistor rO,2 into the " 1 " digit potential divider. These changes in the " 1 " and " 2 " digit potentiometers mean that 0À6 and 0À7 volts would now be necessary to operate the transistors Tr1 and TrO. Accordingly they both cut off and trigger T1 and TO reset. This causes resistor rO,2 to be switched out of the " 1 " digit potential divider so that the response level changes to 0À5 volts. Transistor TrO accordingly re-operates and sets trigger TO. Outputs are accordingly obtained from the " 1 " and " 4 " stages.