This circuit is a simple oscillator. It's frequency is in the range 35 kHz - 60 kHz and it' s adjustable. D1 is infrared LED Values of components are shown in schematic All resistors are 0.25w and all capacitors are 16v With RV1 you can adjust frequency For best result circuit work with 9v battery Pcb size is 2.5cm*3cm
Last week I had a big flood in my house. A water tube broke in the middle of the night making lots of damage. Wooden floor, furniture, small electronic appliances, all damaged due to the water. This made me think on a project that would sense water on the floor and trigger an alarm.
The detector should be able to sense water and trigger an alarm. Also it should be small and battery operated. Battery's voltage should be checked also.
Part List
R1 10K ohms resistor R2 10K ohms resistor R3 10K ohms resistor R4 1K ohms resistor R5 10K ohms resistor R6 1K ohms resistor C1 100nF cap Led1 5mm green led Led2 5mm red led D1 4V7 zener diodePiezo Piezo HPE-120 VR1 78L05 regulator IC1 12F683 SOIC microcontroller from Microchip S1 Push button Others: Box 9V battery clip PCB Metal strips Hex program for the microcontroller
Box and probes
I tried to find a small box that would fit both circuit and box. This way it would be more discrete.
The box that I used did not had enough room for all components, so I had to place both leds and piezo on the exterior of the box. That detail didn't make any difference since the leds should stay visible and the piezo free to make the loudest sound possible.
The probes can be made from any conductive material, but I preferred not to use copper because it deteriorates with time. In my opinion a good material to be used is stainless steel or aluminium. However, maintenance should be done from time to time checking the probes and testing them with water.
Also, the probes should be placed not to far apart from each other and they never should touch each other. The more probe area available for water sensing the better.
The probes I used in my project are made from aluminium.
The probes are bent 90ยบ and glued to the box. They must be parallel to each other always.
The final assembly looks like this:
The detector is placed on the floor. It's possible to use some double side tape and stick the detector against the wall or just leave it like the picture below. The probes are on the bottom of the box touching the floor and the leds on the top.
Hex program
The Hex program must be saved in the microcontroller's memory before soldering on the PCB. Download hex here:ANTIFLOOD.HEX
Testing
Turning on the circuit, both leds and piezo are tested. Also the probes are checked. If the probes are sensing water or any kind of leakage it will turn on the red led and it will trigger the piezo.
After everything is checked ok the detector will enter it's normal state.
Every 10 seconds it will check the probes and the battery's voltage.
If water gets between the probes the detector will enter the alarm mode where the red led will turn on and the piezo will start making a loud sound. The detector will keep itself in alarm mode until S1 is pressed.
If the battery's voltage is good, the green led will flash every 10 seconds but if the voltage reaches 7V the red led will flash every 10 seconds and the piezo will make a short sound to indicate it's time to change the battery.
The water detection time is less than 10 seconds. Since the microcontroller enters a low consumption state between readings to preserve battery life, this state is always 10 seconds long. If water reaches the probes while being in the low power state it will have to wait until it finishes the sleep state before it can trigger the alarm.
Conclusion
This is a simple but effective water detector. I have built 2 units and have one inside the kitchen and one inside the bathroom. It's possible to replace the 9V battery with any 9V wall power supply.
Video
You can check a video of the circuit being tested here:
This circuit is a church bell controller. Basic component is an ATmega32 microcontroller. At the circuit 1 24LC32 eeprom memories is being used.
As control I created a menu who will be appeared on 4x20 LCD (Liquid Crystal Display). The menu browsing can be done by 6 buttons at the face of the circuit's box (Menu, Up, Down, Enter, Start, Stop). The all firmware binds about 30Kbytes flash memory and can be increased by adding new features-functions. This program has been written in C with CVAVR compiler.
The idea of this circuit is being given by a friend of mine who has an foundry and he is building bells. I have made the PCB by my self.
Features
1. More 75 different melodies (ADAM, PANYGJRJKO, AGJORJKO, etc) 2. Control of electrometrical clock of church with the production of pulse of duration 1Sec each one minute. 3. Automatic correction in case of power loss. 4. Percussion of clock each half but also entire hours, with possibility of choice of hours of silence (for tourist regions and hours of common quietness). 5. Manual correction of electromechanical clock. 6. All regulations become with the help of guidance (menu, up, down, enter, start, stop) 7. When it runs a rhythm we have the possibility of increase or decrease her speed, the information will stored in memory 24LC32. 8. Display time (DS1307), with backup battery. 9. All the in formations are displayed on 4X20 LCD. 10. Control up to 5 bells and 1 clock. 11. The user create his own program
This circuit allows a 12v relay to operate on a 6v or 9v supply. Most 12v relays need about 12v to "pull-in" but will "hold" on about 6v. The 220u charges via the 2k2 and bottom diode. When an input above 1.5v is applied to the input of the circuit, both transistors are turned ON and the 5v across the electrolytic causes the negative end of the electro to go below the 0v rail by about 4.5v and this puts about 10v across the relay.
This project is a DC motor driver, suitable for motors that of low or medium power. Allows controlling up to 6 motors or 3 motors if you want to control the rotation of the motors.
Description
The controller is build around the IC L293D that can provide 600mA per channel, and a H-Bridge designed with transistors NPN and PNP transistors, than can provide 1.15A per channel.
The controller has the following connections:
INPUTS (A, B, C, D ,E, F). These are receiving the analog or digital signals that can be sent for example, from a microcontroller.
ENABLE (E1-2, E3-4). These activate the inputs from the L293D. The supply voltage can't be higher than 7V.
OUTPUTS (+M1, -M1, +M2, -M2, +M3, -M3). Here is where the motors should be connected.
+9-12V. Here's where is connected a supply voltage that will give power to the motors. This input, gives voltage in the L293D and the H-Bridge, the supplied voltage have to be 36V max, but for the H-Bridge it's recommendable to use 24V max. (In case you want to use only the L293D, you can remove the jumper).
+5V. This input receive the logic supply voltage for the L293D. You can connect a supply voltage higher than 5V because this input it's connected to a voltage regulator (LM7805), but you not must to exceed 30V.
This circuit controls a load (in this case a dc brushless fan) based on a temperature compared with a setpoint. THe transduced is a diode in the forward polarization regime. In fact when forward biased, the forward voltage drop accross a diode has a temperature dependance, in particular has a negative linear(ish) slope. This because of the boltzmann distribuition, causing electrons to pass to the conduction band thermically, lowering the voltage drop accross the diode.
Anyway this circuit comparates a precise voltage reference (zener) with the forward voltage drop of the diode forward biased with 11mA of current.
The comparator is simply a LM158/258/358 working in open-loop mode, the inverting input is connected to the diode sensor, and the noninverting to the reference voltage. Se when the temperature rises above the setpoint, the forward voltage drops under the voltage reference and the comparator output is vccturning on the transistor and so the fan.
Higher power transistor can be substituted for bigger fans, or you can substitute a relay, IGBT, mosfet etc to control higher loads (and higher voltages).
The setpoint is adjusted with the potentiometer, and you can use a LM3914 led driver to make a temperature setpoint indicator (needs careful calibrations and the use of excel to calculate slope and intercept).
Many modifications can be done, but the circuit works very well in its basic form.
THe comparator can distinguish 10uV differences so approx 0.01°C differences (carefully adjusting the potentiometer can allow to feel body heat from 1/2 cm from the sensor, or feel ambient heat, making to turn the fan on and off continuosly)
You can control temperatures up to 140°C (150 max diode temperature), but linearity is not ensured
Possible uses? Heatsink cooling, computer emergency cooling (but i thint that a linear device would be better than a on-off) metal cooling when drilling etc...
Ah! One note: you can even heat with this circuit but you need the reverse comparator inputs and substitute the fan with a relay controlling the heater.
