VHF UHF HF active antenna electronic circuit project with explanation

A very simple and efficiency active antenna electronic project can be designed using this electronic schematic circuit that is based on transistors. This active antenna electronic project is useful for a wide range of RF frequencies covering three RF bands HF , VHF and UHF . This simple active antenna is designed to amplify signals from 3 to 3000 MegaHertz, including three recognized ranges: 3-30Mhz high-frequency (HF) signals; 3-300Mhz veryhigh frequency (VHF) signals; 300-3000MHz ultra-high (UHF) frequency signals. This HF VHF UHF active antenna contains only two active elements : Q1 (which is  MFE201 N-Channel dual-gate MOSFET) and...

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Posted in: electronic circuit , Radio

DC to AC Inverter by IC 555 and TIP41 TIP42

This be basic AC inverter Circuit. Convenient for the initiator who have to is extremely fond of something experience. Because of use IC 555 highly popular, perform produce the frequency ,then enlarge with transistor NPN and PNP number TIP41 and TIP42 drive the coil transformer. Get by can pay Voltage output about 120V to 230V at frequency 50Hz. By have R4 perform control the frequency and should use. Voltage supply about 5V to 15V the detail sees in circuit picture sir...

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Posted in: electronic circuit , inverter

Free drawing circuit diagram License LGPL

Today younger brother generation that study same college comes to see at a house and beg to seek design good circuit and free. I advises a program TindyCAD because it drawing circuit diagrams commonly known as schematic drawings. It supports model the equipment is a lot of and still apply to PCB layout programs change the system netlist formats. Besides still be usable cooperate SPICE simulation netlists get as well. About the copyright be model freedom License LGPL be usable get freely model open source. Link : http://sourceforge.net/projects/tinycad/...

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Posted in: electronic circuit

Simple Combination Lock by IC 4017 74C14

This simple combination lock accommodates codes from 1-9 digits long, with the only restriction being that the same digit cannot be used twice. The circuit shows strapping for a 4-digit code, in this case “2057″. Any unused switches are strapped to ground. When power is applied, the 330nF capacitor connected to pin 1 of inverter IC1a is discharged, holding it at a logic low level. The high output is inverted by a second gate (IC1b), with the result being a logic low on pin 4. This pulls Q1’s emitter low via D1, causing the transistor to conduct. The falling voltage on the collector then pulls the input of IC1c low, which in turn resets counter...

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Super Sensitive Intruder Alarm

Here is the circuit diagram of an ultra sensitive intruder alarm.The shadow of an intruder passing few meters nearby the circuit is enough to trigger the alarm. Here IC2 uA 741 is wired as a sensitive comparator ,whose set point is set by R6 &R7.The voltage divide by LDR and R9 is given at non inverting pin of IC2.At standby mode these two voltages are set equal by adjusting R9.Now the out put (pin6) of comparator will be high.Transistor Q1 will be off.The voltage at trigger pin of IC1 will be positive and there will be no alarm.When there is an intruder near the LDR the shadow causes its resistance to increase. [......

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Posted in: Alarm home system , alarm systems , electronic circuit

Window foil burglar alarm with scr

Here is a simple but effective burglar alarm circuit that can be fixed on windows to detect break throughs. The circuit uses a fine wire element fixed as a network through the window glass for sensing the break through . Normally the base of Q1 is held to ground potential by the wire element.So Q1 will be off and SCR H1 will not be conducting,and horn will be off.When the wire element is broken the base of Q1 will be raised to positive potential, Q1 will be on and so SCR H1 (TYN 612) will be ON making the horn to blow and this condition will be latched by the SCR.The circuit remains ON until the normal condition is restored or the power supply...

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Posted in: Alarm home system , alarm systems , electronic circuit

Night security light

Here is a simple circuit switches on a light around 2 hours after midnight, the time at which most of the robberies taking place. This simple circuit is build around a CMOS IC 4060 to obtain the required timing. During day time the LDR has low resistance and keeps the pin 12 of the IC1 high, preventing the IC1 from oscillating. When it is dark the LDR resistance becomes high and the pin 12 of IC1 becomes low and the IC starts oscillating, which indicated by the flashing of LED D3.The values of the timing components R1, R2, C4 are so selected that the out put pin3 of IC1 goes high after 8 hours. That means the high output drives the triac to...

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Posted in: Alarm home system , alarm systems , electronic circuit , Lighting

Petrol Gas Switch For A Pajero

My current vehicle, a Pajero, was modified for dual fuel – ie, petrol and gas. However, it’s necessary to run the vehicle on petrol at regular intervals to stop the injectors from clogging up. This simple circuit allows the vehicle to be started using petrol and then automatically switches it to gas when the speed exceeds 45km/h and the brake pedal is pressed. Alternatively, the vehicle may be run on petrol simply by switching the existing petrol/gas switch to petrol. You can also start the vehicle on gas by pressing the brake pedal while starting the vehicle. The circuit is based on an LM324 dual op amp, with both op amps wired as comparators....

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Posted in: Alarm home system , electronic circuit , Lighting

Wireless Protable Intercom Voice Activated

Chamberlain wireless portable inte- Provides convenient and expandablemunication for your home- Advanced features include voice activation and monitor mode- Crystal clear secure 900 MHz digitalmunication- 1000 Foot rangeCHNLS2 Technical Details * This wireless intercom system has an amazing 1000 ft. * This portable wireless intercom system is fully expandable to an unlimited number of intercom stations that share 4 Channels. * The Monitor Mode features the most advanced Voice Operated Switch (VOX) allowing you to customize sensitivity settings * Secure 900 MHZ radio link. Compact size- each intercom unit measures less than 4″x5.5″x2″....

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Posted in: Alarm home system , electronic circuit

Low Cost Burglar Alarm For Boats

This low-cost burglar alarm employs a 12V strobe light and a truck reversing horn as the visible and audible alarm outputs while the alarm itself is a 12V horn relay and some pressure mat switches. This simple approach has the benefit that the alarm continues to operate even if the entry point is immediately closed and it draws no current while in the armed condition. To make it independent of the boat supply it runs from a single 12V or two 6V alkaline lantern batteries connected in series. These should last well in excess of two years. An advantage of a lantern battery is that it will last less than an hour while powering the alarm in its...

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Posted in: Alarm home system , electronic circuit

Fridge door Alarm

Beeps if you leave open the door over 20 seconds 3V battery operation, simple circuitry This circuit, enclosed into a small box, is placed in the fridge near the lamp (if any) or the opening. With the door closed the interior of the fridge is 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 enters from the opening, or the fridge lamp illuminates, the photo resistor lowers its resistance (<2K), pin 12 goes low, IC1 starts counting and, after a preset delay (20 seconds in this case) the piezo sounder beeps for 20 sec. then stops for the same lapse of time...

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Posted in: electronic circuit

12V Battery Charger

Solid state two color LED indicates stage of charger; a quick connect harness for use in hard to reach areas Perfect for all lead-acid, flooded or sealed maintenance free batteries (AGM and gel cell) Complete 4-step charging program (initialization, bulk charge, absorption mode and float mode) that maintains batteries at full charge without overcharging via its 4-step charging system Automatically switches to float/maintenance mode voltage after fully charging the battery Temperature compensated to ensure optimum charge voltage according to ambient temperature, and spark proof and reverse polarity protected; 10-year limited warrant...

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Simple Battery Isolator

This circuit is even simpler and employs a 6V feed from one of the stator connections on the vehicle’s alternator. This is connected to a 6V automotive relay (RLY1) which controls a Continuous Duty Solenoid (RLY2). This solenoid electrically connects or isolates the batteries. When the engine is started and the alternator stator voltage rises, the 6V relay turns on. This turns on the Continuous Duty Solenoid to connect the two batteries in parallel. As long as the engine is running, the vehicle’s alternator will maintain charge in both batteries. When the engine is shut down, the alternator stator voltage drops and the Continuous Duty Solenoid...

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Posted in: electronic circuit

Easy dry cell charger with CMOS IC 4011

The dry cell charger circuit can be fully charged about 12 hours.When used with a 9 volt supply,the equipments in the circuit for the AA type cell.When using the C and D type cell, should reduce the value of the resistance Rx to be 68 ohms.In charge of the cell, you should not be charged to the same series, may cause cell damage is fully charged. If the cell voltage is below 1.6 volt,The compared circuit to leave the square wave oscillator by the CMOS gate,then the transistor made a charge until the cell voltage is 1.6 volt.The comparison circuit will cut the charging LED blinks, notice prevents over-charging...

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Posted in: electronic circuit

alarm with countdown timer

This circuit is IC implementation schedule. No. 555 applied with IC number LM3905.By the IC to the number 555 are the circuits Stable multi-vibrator. How often do produce it.This frequency is then forwarded to the scheduling with the integrated circuit number LM3905. When entering the power supply circuit IC1 No. 555. To be atable multivibrator circuit. Produce about 0.5 hertz frequency out.The R1, VR1, R2 and C1 determine the frequency.The output pin 3 will be out of a square wave LED1 will be lit.The signal is a negative split.and LED2 will be lit during a split positive signal.This will flash alternately throughout the duration of scheduled....

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Simple Wireless Security Alarm For Car

Alarm circuit is functioning as a car wireless security alarm. Yes, this is an FM radio-controlled anti-theft alarm. This alarm can be used on any vehicle that has a DC power supply 6-12V. Alarm circuit system is divided into two parts, the transmitter unit and receiver unit. Transmitter unit is working on the range of VHF Band II, exactly at a frequency of 88-108 MHz. This transmitter is a miniature FM transmitter that is installed in vehicles at night while parked in the car porch or car park. Simple Car Wireless Security Alarm SchematicThe receiver is a single IC-based FM radio module, CXA1019, kept inside. Receiver tuned frequency matches...

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Posted in: electronic circuit