Here this circuit I used PIC Basic Pro for counting. Counting can start from 0 to 999. After it reached 999, it will go to zero automatically. In this project, INTCON Register, OPTION Register are used to control timer interrupt. I also put the source code, circuit here. (7-12-2015)
Here is the one that I have tested the digital thermometer with LCD display. Although I got the sensitive device, I couldn't change the decimal place. It showed 226.5Degree C instead of 22.65 Degree C. The schematic circuit diagram is shown below. The circuit design was not mine. I got the circuit and source code from this site http://www.rentron.com/ . But I'm very happy to test this device.
This is the schematic diagram that I've made
Here is the Device that I've set up
Here is a good sensitive Solid State LED Thermometer that I have ever made. It was constructed by using only LM35DZ temperature sensor and LM3914 Dot/Bar display driver IC. This device can display 10C to 100C with 10 Degree centigrate per LED.So we can easily known how much about temperature. But It can't do exactly since its a solid state LED display. It will turn on 1st LED within 10C and 20C. And then it will turn on 2nd LED if the temperature is between 20C and 30C and so on. You can only need a few part to construct this circuit as DIY.
In order to calibrate within the desire range, we must place the temperature sensor at 100 Degree Celcius boiling water and adjust the 5K POT to bright no(10)LED and place the temperature sensor at 10 Degree Celcius water and adjust the 5K pot again to bright no(1)LED. Room temperature is about 26 Deg Celcius, So put the ICE into the water to get 10DEg Celcius. After this step, this device is ready to use.Check the Schematic Circuit Diagram to understand clearly. May be happy!
1) LM35DZ IC
2) LM3914 IC
3) 100K Potentiometer
4) 5K Potentiometer
5) 5V and 12V Power Supply or 9V battery
Automatic Outdoor Light
Here is a good automatic outdoor light with circuit and devices. This circuit is my own idea. It is very cheap, simple circuit components and sensitive device to operate. You can eisily build this circuit withhin 20 minutes as DIY project.The circuit is given below:
As we know, silicon has 0.7V for the barrier potential. So we can trn on the BJT transistor over 0.7V. In this project, the transistor C945,npn transistor was used. There is no problem for transistor selection detail. The transistor in this project only need to use as a switch. Ok! lets check the circuit operation. Resistor R1 is a vairable resistor(POT) used as voltage divider. Voltage divider equation is Vout = (R2/R1+R2)Vcc. By using the POT(variable resistor), we can easily adjust the output voltage of the voltage divider by truning the POT as we need. The current from voltage divider flows to LDR(Light Dependent Resistor). LDR was constructed by electronic compaines in terms of Albert Einstein's well known photoelectric effect in 1905. So when light falls on the LDR, the current in LDR rises and LDR alllows the current to pass through it and flows into the input of the transistor's base lead. If the voltage is over 0.7V, the transistor becomes saturate(turn on) and draws the collector current to emitter.At the same time, electromagnetic relay energizes and turn off the light bulb. It will depend on our desire to turn ON or turn OFF the output light bulb by using relay contact with NC(normally close) and NO(normally open).
Even the circuit is simple, we have to calibrate the circuit. (1)Cover the LDR or not allow any light on LDR. (2)Turn R1 slowly till the light bulb glow.(3)When the light bulb glows, remove the cover from LDR or let the light to fall on LDR. After these 3 steps, we have cooked our circuit and can be used as low cost automatic outdoor light. This circuit has been tested.
1) 5V relay 1 No.
2)100KOhm POT 1 No.
3)C945 (general purpose npn) transistor 1 No.
4)9V battery 1 No.
5)100W electric bulb, some wires, universal PCB.
The ultrasonic transducer was used in this device as main input. The resonant frequency of this ultrasonic transducer is 40kHz. The operation of the circuit is (1) Catch the ultrasound with ultrasonic transducer (2) amplified the input signal with LM386 Audio amplifier IC at two stage cascaded condition (3) Put the amplified signal to the AN6884 LED Audio UV display driver circuit. According to the input signal's amplitude the device will be shown with LEDs when detecting Bats. The circuit is very simple that I've ever made.
schematic circuit diagram
Internal Circuitry Array
Full Scale Detection Mode
This is a microcontroller based instruments on project board, I got this circuit and source code from here http://embedded-lab.com/blog/?p=4333. Good and pricese. It uses DHT11 sensor, pic16f628 mainly.
I made it with my 3rd Year students. The project idea is so easy. LDR is provided the light by LED. When the hand is between LED and LDR, the current change and it triggers the transistor. The transistor draw the current to energize the electromagnetic relay. The relay turns on and off to Hair dryers.. cool!
with complete circuit diagram
I made it with PIC16F628A Microcontroller. 7 Leds are connected to PIC. Circuit power is provided by 9V battery.
LM7805 IC used as regulator. Circuit and Testing event are shown.
This device is simply constructed with basi electronicc devices ideas. All we need is main transformer, 1A diode, zener diode, relay, some resistors and LEDs. If the voltage exceeds 230V, the zener will trigger transister and transister will switch relay again. Please feel it. Cool!
Complete circuit diagram
Project device photo
Internal circuitry array photo