Communications: electrical – Continuously variable indicating – With particular receiver
Patent
1988-08-26
1990-09-25
Weldon, Ulysses
Communications: electrical
Continuously variable indicating
With particular receiver
307353, 34082507, 34082539, G08C 1902
Patent
active
049596497
ABSTRACT:
A current holding circuit of a two-wire instrument which includes a transmitter and a receiving resistor, remotely located from the transmitter, for detecting a signal from the transmitter as a change in loop current, and to which a commuication device is connected, includes a current detecting unit, a sample-hold unit, and a current control unit. The current detecting unit includes a reference resistor for converting the loop current into a voltage and a first operational amplifier for receiving the voltage obtained by the reference resistor at the noninverting input terminal. The sample-hold unit holds an output from the current detecting unit. The current control unit supplies an output from the sample-hold unit to the inverting input terminal of the operational amplifier and controls the loop current on the basis of the output from the operational amplifier, thereby holding the loop current at a constant value.
REFERENCES:
patent: Re30597 (1981-05-01), Grindheim
patent: 4401974 (1983-08-01), Jarrett et al.
patent: 4420753 (1983-12-01), Meyer-Ebrecht
patent: 4651034 (1987-03-01), Sato
patent: 4831375 (1989-05-01), Kajiura
Weldon Ulysses
Yamatake-Honeywell Co. Ltd.
LandOfFree
Current holding circuit of two-wire instrument does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Current holding circuit of two-wire instrument, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Current holding circuit of two-wire instrument will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-331247