The humidifier circuit is based on a special humidity sensor Type NH-3 from Figaro. Depending on the sensor output, the circuit drives a ventilator that is part of an air humidifying installation. The ventilator is switched on an off by a triac. So as to keep the circuit as simple as possible, the supply voltage and the test voltage are drawn dire
Click here to download the full size of the above Circuit.
ctly from the mains supply. The 240 V mains voltage is converted into an 8. 9 V pulsating direct potential by capacitor C1, resistor R1 and zener diode D1. The pulsating voltage is used to drive the sensor. It is also transformed to a 7. 5 V supply voltage by D2 and C2. The sensor needs an alternating drive voltage at a level not higher than 1. 5 V. This potential is obtained from the pulsating direct voltage by network R2-R3-C3-C4, which removes the direct voltage component and lowers the level to 1. 4 V. At the same time, the network functions as a 50 Hz bandpass filter. To ensure that the drive voltage for the sensor does not fall outside the common-mode range of op amp IC2, an offset potential of 3. 9 V is applied to the sensor as well as to the voltage reference source of the op amp. This potential is provided by zener diode D3. The reference level is set with P1. The op amp is given some hysteresis by R5. When the humidity of the ambient air rises above that corresponding to the level with P1, the output voltage of IC2 is about 6 V. This results in T1 being cut off by D4, whereupon the triac is also disabled. When the humidity drops below that corresponding to the level set with P1, a pulsating potential appears at the output of IC2. This voltage is used to charge capacitor C6. The charged capacitor thereupon provides a steady current to the triac. When T1 is cut off for some time, capacitor C6 is discharged via...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
characters left: