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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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Datasheet «LM1830»

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

The probe must be placed at the level you want to monitor.

With the give value of C1 the frequency will be around 6KHz. For non metal tanks fix a small metal contactor at its bottom level and ground it. Hi Challa it is meant for normal water, hence can be used for our domestic use to control over head tank water level. Resistor R3 limits the collector current of the internal transistor while resistor R4 provides protection to the IC from transients.

A method for activating a relay when the liquid level exceeds a predetermined level is shown here. Hi Rohit Pin No 5 is oscillator out put for external reference resistance. Datsheet 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. The load connected through the relay whether pump, lamp, alarm, solenoid valve or anything is driven.

Capacitor Ct sets the frequency of the internal oscillator. Hai, Can it be ratasheet for Water level indicator in a Over head Tank. You may see the circuit if you are interested. Pin 9 of the IC can be used to solve this problem.


LM datasheet & applicatoin notes – Datasheet Archive

Please refer to the second circuit above. Some time there may be situations when the fluid resistance probe to ground do datasheeg match with the 13K internal reference resistor. Level indicator using external reference resistor.

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 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. 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. The probe used here can be any metal rod with size and shape of your choice.

The tank must be made of metal and it should be properly grounded. Liquid level indicator admin October 12, 11 Comments. 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 load that is the relay is connected at the collector of Q1. You have to connect the tweeter between Pin No12 and Vcc through suitable resistance. Hi, can this sensor circuit be used to detect diesel fuel? The oscillators output is directly available at pin 5 and the Rx connects the oscillator output to the probe through the blocking capacitor.

Previous post Next post. Usage of AC signal for detection prevents electrolysis and this makes the probes long lasting.

How could I use this circuit to control the Digital input on a microcontroller? Your email address will not be published. Manufactured by National Semiconductors, the LM can detect the presence or absence of polar fluids.


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. The circuit of a low liquid level indicator with LED is shown above. 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.

You may also like: Low liquid level indicator LED. Achei fantastico o site. Leave a Reply Cancel reply Your email address will not be published. High liquid level activated switch. 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. LM based liquid level indicator circuit. Atenciosamente… Washington Souza Gomes. The circuit detects the fluid level by comparing the probe to ground resistance with the internal reference resistor R ref.

The circuit diagram for the above said scheme is shown below. The LED connected to the collector between pin 12 and Vcc is driven.

Loud speakers can be driven only by using AC signals and a DC signal will not produce any sound out of the speaker. The circuit diagram of a liquid level indicator using loud speaker at its output is shown below. Low liquid level warning audio. External transistor Q1 is connected to the collector of the internal transistor. Circuits based on this IC requires minimum number of external components and AC signal is passed through the sensing probe immersed in the fluid.