Low Voltage Monitor schematic

Low Voltage Monitor circuit is highly desirable for security and protection against everyday damage your equipment, especially for your favorite car. This circuit may be very simple / very simple to make because only by using ic LM339. The workings of this circuit is Buzzer will sound and lights Led will light up when your car battery in a state of tension is very minimal. Although the circuit is very simple but can protect your car from damage that would be very detrimental. This voltage monitor circuit may be beneficial to you.

Component List:

R1, R3 2 1K 1/4W Resistor
R2 1 5K Pot
U1 1 LM339 Voltage comparator IC
D1 1 1N5233B Zener Diode
D2 1 LED
BZ1 1 Piezo Buzzer
MISC 1 Board, wire, socket for IC

Notes
1. The circuit will operate from 9V to 12V.
2. Adjust R2 until the alarm goes off at the correct voltage.

Digital Decade Counter Schematic

Decade counter circuit is a befungsi electronic circuit to perform a sequence of numerical calculations either forward or backward calculation. What is meant by forward calculation is where the circuit will count ranging from small numbers to larger numbers. While the countdown to the contrary. Calculations can reach an unlimited number of circuits or design depending on the demands.

A lot of the usability of this counter circuit in the world of digital electronics. It could even be said to be an integral digital electronics with a series of counters. Almost all digital circuits require a series of counters. That's because to implement the functions of numerical or mathematical operations must use the functions of the counter circuit.

For the decade counter circuit above is the use of the family of CMOS IC. Where for all types of CMOS IC can use a maximum supply voltage of 15 volts, whereas TTL only have a maximum supply voltage of 5 volts. Then, using 74ls48-74ls90 as the decade counter IC you no longer need to use as an interface to the decoder IC 7-segment. Because the output generated by the 74ls48-74ls90 has been adapted to the conditions and functions of the seven segment.




Deliberate use of the above series of ignition Schmitt Trigger gate as a damper mechanical switch bounce of the beat. You may not use the gate Schmitt trigger input and switch directly connects to the clock pin IC 4026. Counter circuit you will keep running, but you will find a hopping chopped or shredded irregular.
 

Refrigerator Alarm schematic

Refrigerator Alarm circuit, so that we know whether the fridge is closed or not. Refrigerator sometimes likes to play or open the lid by the children, and this resulted in a refrigerator at room temperature decreases and will increase the electrical load, so that the electricity to be extravagant. Therefore it is necessary alarm circuit.

Alarm circuit schematic drawings Refrigerator

Circuit placement and How it Works: This circuit is stored into a small box, placed in the fridge near the lamp (if any) or the opening. With the door closed in the refrigerator in the dark, the photo resistor R2 presents a high resistance (> 200K) thus clamping IC1 by holding pin 12 high. When a beam of light came when opening, or a refrigerator light bulbs, photo resistor lowers resistance (<2K), pin 12 so low, IC1 starts counting after a predetermined delay (20 seconds) piezo sounder beeps sound for 20 seconds. then stopped during the same time interval and the cycle repeats until the fridge door closed. D2 is connected to pin 6 of IC1 allows the piezo sounder beeps sound 3 times per second.

List of Components:

R1 10K 1/4W Resistor
R2 Photo resistor (any type)
R3 R4 100K 1/4W Resistors
C1 10nF 63V Polyester Capacitor
C2 100µF 25V Electrolytic Capacitor
D1,D2 1N4148 75V 150mA Diodes
IC1 4060 14 stage ripple counter and oscillator IC
Q1 BC337 45V 800mA NPN Transistor
BZ1 Piezo sounder (incorporating 3KHz oscillator)
SW1_________Miniature SPST slide Switch
B1   _________3V Battery (2 AA 1.5V Cells in series)