Liquid Sensing Circuits

Using a capacitor sensor to detect a water level is a simple method of sensing. This circuit uses C5, which..

Views: 74 | Votes: 44 | Comments: 0 | Rating: 0 | Rank: 5 | Added: Mar 14, 2013 |

When liquid level reaches both probes, alarm is turned on..

Views: 485 | Votes: 69 | Comments: 0 | Rating: 2 | Rank: 5 | Added: Feb 24, 2013 |

In this a warning device WD1 is in series with SCR1. When the liquid level causes a conductive path between the probes, the SCR conducts sounding WD1. The warning device may be a Sonalert (TM), a lamp or a buzzer.D1 acts as a transient suppressor. ..

Views: 4966 | Votes: 28 | Comments: 0 | Rating: 3 | Rank: 4 | Added: Feb 19, 2013 |

Although many circuits use the varying-capacitance method for checking liquid levels, this simple resistive circuit is much easier to construct. Even a tank of a liquid, such as water, has sufficient conductive salts in solution for this method to work. The probe uses a metal rod that supports 10 insulated wires, which have stripped ends pointing down. As the level of liquid rises, resistors Rl through Rl0 are successively brought into circuit, each drawing an extra 10.....

Views: 27 | Votes: 92 | Comments: 0 | Rating: 6 | Rank: 5 | Added: Feb 13, 2013 |

Using a few bipolar transistors, this circuit acts as a flood alarm. When liquid touches the probes, leakage current biases Ql,..

Views: 19 | Votes: 75 | Comments: 0 | Rating: 1 | Rank: 5 | Added: Feb 9, 2013 |

Use this circuit to keep the fluid level of a liquid between two fixed points. Two modes, for filling or emptying are possible by simple reversing the contact connections of Kl. The loads can be either electric motors or solenoid operated valves, operating from ac power. Liquid level detection is accomplished by two metal probes, one measuring the high level and the other the low level..

Views: 3554 | Votes: 8 | Comments: 0 | Rating: 5 | Rank: 5 | Added: Feb 1, 2013 |

The circuit uses four NAND gates of a 4011 package. In each oscillator, while one gate is configured as a straightforward inverter, the other has one input that can act as a control input. Oscillator action is inhibited if this input is held low. The first oscillator (ICla and IClb) has this input tied low via a high value resistor (Rl) that acts as a sensitivity control. Thus this oscillator will be disableduntil the control input is taken high. Any moisture bridging the.....

Views: 2493 | Votes: 36 | Comments: 0 | Rating: 3 | Rank: 5 | Added: Jan 27, 2013 |

A bridge rectifier and 12-volt regulator powers the MOSFET sensing circuit. The unregulated output of the bridge rectifier operates the drain solenoid via switch SI. The sensor itself is built from two electrodes, one made of copper, the other of lead. In combination with the liquid trapped by the sensor, they form a miniature lead-acid cell whose output is amplified by MOSFET Ql. The maximum output produced by our prototype cell was about 50 µ. MOSFET Ql serves as the.....

Views: 812 | Votes: 83 | Comments: 0 | Rating: 0 | Rank: 6 | Added: Dec 29, 2012 |

The circuit draws so little current that the shelf-line of the battery is the limiting factor. The only current drawn is the leakage of the transistor. The circuit is shown in the form of a water level alarm but by using different forms of probe can act as a rain alarm or shorting alarm; anything from zero to about 1M between the probes will trigger it. Q1 acts as a switch which applies current to the unijunction relaxation oscillator Q2..

Views: 744 | Votes: 0 | Comments: 0 | Rating: 4 | Rank: 5 | Added: Dec 21, 2012 |

This monitor uses a common 7 41 amp configured as a comparator and a low cost nontransistor as an output driver. With no liquid detected, a voltage of about 2. 92 V is present in the op amp"s inverting input at pin 2. The 100-KO resistors establish a reference voltage of +2. 5 V at the noninverting input at pin 3 of the op amp. Under those conditions, the op amp"s output is -3.56 V, which keeps the 2N2222 transistor turned off and the voltage across its 1-KO.....

Views: 21 | Votes: 43 | Comments: 0 | Rating: 1 | Rank: 5 | Added: Dec 21, 2012 |

To calibrate the gauge, connect the battery and press the probes gently into a pot containing a plant that is just on the verge of needing water (stick it in so that only an inch of the probe is left visible at the top). Turn the potentiometer until the "OK" LED lights and then turn it back to the point where that LED goes out and the ''W", or ' 'Water", LED just comes on. ..

Views: 4939 | Votes: 59 | Comments: 0 | Rating: 9 | Rank: 5 | Added: Dec 3, 2012 |

The circuit applies power to the load until the water conducts through the probe, and bypasses gate current from the low current SCR..

Views: 5042 | Votes: 53 | Comments: 0 | Rating: 0 | Rank: 5 | Added: Dec 1, 2012 |

The unit consists of a sensor, timer, and electric water pump. The sensor is embedded in the soil, and when dry, the electronics operate the water pump for a preset time. The circuit is composed of a level sensitive Schmitt trigger, variable time monostable, and output driver. When the resistance across the probe increases beyond a set value (ie, the soil dries), the Schmitt is triggered..

Views: 4013 | Votes: 22 | Comments: 0 | Rating: 4 | Rank: 5 | Added: Nov 30, 2012 |

Running a bath can end in a minor domestic disaster if you forget to turn off the taps in time. This indicator activ..

Views: 16 | Votes: 51 | Comments: 0 | Rating: 3 | Rank: 5 | Added: Nov 30, 2012 |

This circuit uses an ac-sensing signal to eliminate electrolytic corrosion. The ac signal is rectified and used to driv..

Views: 24 | Votes: 62 | Comments: 0 | Rating: 6 | Rank: 5 | Added: Nov 25, 2012 |

Alarm is actuated when liquid level is above the probes and remains activated even if the level drops below the probes..

Views: 5588 | Votes: 93 | Comments: 0 | Rating: 4 | Rank: 5 | Added: Nov 23, 2012 |

The detector is made of fine wires spaced about one or two inches apart. When the area between a pair of wires becomes moistened, the horn will sound..

Views: 2032 | Votes: 26 | Comments: 0 | Rating: 1 | Rank: 5 | Added: Nov 16, 2012 |

A nice and small Fluid (water) sensor circuit that drives a relay for every use that comes to your head :)..

Originally, this circuit was used to sense a low-water level in a Christmas tree stand, but the circuit can be use..

Views: 16 | Votes: 87 | Comments: 0 | Rating: 9 | Rank: 5 | Added: Oct 12, 2012 |

With SI open the circuit functions as a doorbell. With SI closed, rain falling on the sensor will turn on Ql, triggering Q2 and the thyristor and activating the bell, R4 provides the holding for the thyristor while Dl prevents any damage to the thyristor from back EMF in the bell coil. The sensor can be made from 3 square inches of copper clad board with a razor cut down the center..

Views: 3925 | Votes: 33 | Comments: 0 | Rating: 7 | Rank: 5 | Added: Sep 10, 2012 |