LM Fluid Detector. The is a monolithic bipolar integrated circuit designed for use in fluid detection systems The circuit is ideal for detecting the presence. LM datasheet, LM circuit, LM data sheet: NSC – Fluid Detector, alldatasheet, datasheet, Datasheet search site for Electronic Components and. LM Datasheet, LM PDF, LM Data sheet, LM manual, LM pdf, LM, datenblatt, Electronics LM, alldatasheet, free, datasheet.

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Level indicator using external reference resistor. DC voltage is required for driving the relay and AC voltage cannot be used here just like what we did in the case of LED and speaker. High liquid level activated switch. You may also like: When the reverse scenario occurs fluid level touches the probe the internal transistor is switched OFF and this in turn makes the transistor Q1 ON resulting in the activation.

Loud speakers can be driven only by using AC signals and a DC signal will not produce any sound out of the speaker. Low liquid level warning audio. Low liquid level indicator LED. Hi Challa it is meant for normal water, hence can be used for our domestic use to control over head tank water level. The circuit is similar to the first circuit except that the LED is replaced by a loud speaker and the load current limiting resistor is changed from 1.

Liquid level indicator admin October 12, 11 Comments. Hi, can this sensor circuit be used to detect diesel fuel? External transistor Q1 is connected to the collector of the internal transistor. Please refer to the second circuit above.

The load that is the relay is connected at the collector of Q1. Hi Rohit Pin No 5 is oscillator l1m830 put for external reference resistance. The circuit diagram for the above said scheme is shown below. The tank must be made of metal and it should be properly grounded. The probe must be placed at the level you want to monitor.


Capacitor Cb couples the oscillator output to the probe and it ensures that no DC signal is applied to the probe.

(PDF) LM1830 Datasheet download

When the probe is not touching the water it equal to an open circuit situation and surely the probe resistance will be many M ohms and it is greater than the R ref 13K. Datxsheet of AC signal for detection prevents electrolysis and this makes the probes long lasting. For non metal tanks fix a small metal contactor at its bottom level and ground it. When the probe to ground resistance goes above the R ref the oscillator output is coupled to the base of the internal output transistor making it conducting.

The circuit detects the fluid level by comparing the probe to ground resistance with the internal reference resistor R ref.

Liquid level indicator circuits using LM

You may see the circuit if you are interested. Pin 9 of dwtasheet IC can be used to solve this problem. Manufactured by National Semiconductors, the LM can detect the presence or absence of polar fluids. The circuit diagram of a liquid level indicator using loud speaker at its output is shown below. The oscillators output is directly available at pin 5 and the Rx connects the oscillator output to the probe through the blocking capacitor.

Capacitor Ct sets the frequency of the internal oscillator. You have to connect the tweeter between Pin No12 and Vcc through suitable resistance. Atenciosamente… Washington Souza Gomes. Resistor R3 limits the collector current of the internal transistor while resistor R4 provides protection to the IC from transients. Your email address will not be published.

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The load connected through the relay whether pump, lamp, alarm, solenoid valve or anything is driven. How could I use this circuit to control the Digital input on a microcontroller?

Some time there may be situations when the fluid resistance probe to ground do not match with the 13K internal reference resistor. A capacitor connected from this pin to ground will keep the internal output transistor steadily ON whenever the probe resistance goes higher than the reference resistor.

Achei fantastico o site. Leave a Reply Cancel reply Your email address will not be published. The internal transistor will be switched ON and Q1 whose base is connected to the collector of the internal transistor will be in OFF condition keeping the relay inactive. The circuit of a low liquid level indicator with LED is shown above.

LM National Semiconductor Fluid Detector ChipFind Datasheet Archive |

Previous post Next post. With the give value of C1 the frequency will be around 6KHz. There is no problem in driving the LED using Datasheeg signal and this method is very useful when it comes to use a loud speaker as the indicator.

In such cases there is option to avoid the internal reference resistor and an external reference resistor of your choice Rx in the circuit can be employed.

A method for activating a relay when the liquid level exceeds a predetermined level is shown here. The LED connected to the collector between pin 12 and Vcc is driven. Circuits based on this IC requires minimum number of external components and AC signal is passed through the sensing probe immersed in the fluid. Hai, Can it be used for Water level indicator in a Over head Tank.