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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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. The tank must be made of metal and it should be datasgeet grounded. The oscillators output is directly available at pin 5 and the Rx connects the oscillator output to the probe through the blocking capacitor.

Achei fantastico o site. Manufactured by National Semiconductors, the LM can detect the presence or absence of polar fluids. 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 diagram for the above said scheme is shown below. For non metal tanks fix a small metal contactor at its bottom level and ground it. Atenciosamente… Washington Souza Gomes.

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. Leave a Reply Cancel reply Your email address will not be published.

The LED connected to the collector between pin 12 and Vcc is driven. 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.


Circuits based on this IC requires minimum number of external components and AC signal is passed through the sensing probe immersed in the fluid.

Liquid level indicator circuits using LM

The load that is the relay is connected at the collector of Q1. Low liquid level indicator LED. DC voltage is required for driving the relay and AC voltage cannot be used here just like what we did dahasheet the case of LED and speaker.

The circuit diagram of a liquid level indicator using loud speaker at its output is shown below. 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. Liquid level indicator admin October 12, 11 Comments. Please refer to dtasheet second circuit above.

The probe must be placed at the level you want to monitor. With the datashete value of C1 the frequency will be around 6KHz. Capacitor Cb couples the oscillator output to the probe and it ensures that no DC signal is applied to the probe.

You have to connect the tweeter between Pin No12 and Vcc through suitable resistance.

(PDF) LM1830 Datasheet download

Hi Rohit Pin No 5 is oscillator out llm1830 for external l1m830 resistance. Previous post Next post. The circuit is similar to the first circuit except that the LED is replaced by a loud speaker and the lm1380 current limiting resistor is changed from 1. Pin 9 of the IC can be used to solve this problem. High liquid level activated switch. External transistor Q1 is connected to the collector of the internal transistor.


Capacitor Ct sets the frequency of the internal oscillator. 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.

There is no problem in driving the LED using AC signal and this method is very useful when it comes to use a loud speaker as the indicator.

The circuit detects the datasueet level by comparing the probe to ground resistance with the internal reference resistor R ref. Some time there may be situations when the fluid resistance probe to ground do not match with the 13K internal reference resistor.

The probe used here can be any metal rod with size and shape of your choice. The load connected through the relay whether pump, lamp, alarm, solenoid valve or anything is driven.

Low liquid level warning audio. LM based liquid level indicator circuit. Level indicator using external reference resistor.

Hai, Can it be used for Water level indicator in a Over head Tank. 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. You may see the circuit if you are interested.