Circuit Wiring Solution: a

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Wednesday, November 19, 2014

Building a radio station

Requires us to make things systematically and efficiently, because time is very valuable to us, then some of the advances in technology has been applied in various fields, including education, because this is where all the technological advances developed.Lots of technology is rapidly expanding in our country today. With technology growing by leaps and bounds this is what will make the work more systematic and efficient.Based on our technological advances and his friends create a system are related to the Electronics course, we propose the same faculty to develop a community tool. We got a second job in four semesters, which makes the FM transmitter.

Departing from hobby assembling electronic items, we try to assemble a mini-power transmitter that can emit a short signal of approximately 100 meters with power (power) 5 watts. This is a pilot who later became 12 watts. With 12 watts of power, radio broadcasts to reach a village.

1.2 Formulation of ProblemProblems are handled from this lab assignment is to create and analyze the quality of an FM transmitter to get the data at test point 1, point 2 test, test point 3 and the exact frequency as desired.Things are of practical tasks is restricted only to analyze the quality of a transmitter and retrieve data from an existing test point.

1.3 LimitationsProblems to be addressed in this lab assignment is limited to some of the following:1 • Retrieving data from the frequency and calculate TP 1 to TP 3.2 • Analyze a transmitter in the room, based on measurement data and make conclusions.

1.4 ObjectivesObjectives to be achieved in this task are:A. Students can design and make the circuit in fm transmitter.2. 12 Watt FM transmitter that can be made of appropriate tools and can be marketed.

1.5 MethodologyIn completing this lab assignment, the steps are as follows:1 • Learn about basic electronics concepts and learn concepts about the mechanism of FM modulation.2 • Analyze and conclude the experimental results, and give advice when it is applied to the practical task of the real system.3 • Preparing a report on second semester practicum assignment.

1.6 DiscussionThis book of this lab assignment consists of 5 (five) chapters, in each chapter related to one another, namely:

CHAPTER 1:Provide background on the issues, goals, problems and constraints of the problems discussed in this lab assignment.CHAPTER 2:Provide the theoretical basis to support problem solving in this lab assignment. The basic theory is given include: the mechanism of the tool inused in making the FM transmitter

CHAPTER 3:Planning and manufacture of tools and how each blog diagram contained in FM transmitterCHAPTER 4:Contains the results of calculations and data processing, and analysis resultscalculation.CHAPTER 5:Provide conclusions about the results already obtained and suggestions.CHAPTER IIBASIC THEORY

2.1 Koker

Koker serves to regulate or determine the frequency of the radio transmitter. In koker also Ferrite that serves as a core inductor in addition there is an inductance coil comprising primary and secondary winding. Way of working is to facilitate search koker empty wave. When filling koker in turn to the right to a maximum frequency of the oscillator produce more low. If the FM transmitter lights, turn left up the core koker to hissing on the FM radio signal is lost it will be found a strong and stable.

2.2 Inductor

Coil of wire that is wrapped with a particular matter, in this case to determine the value of the inductor is typically used Q-meter. Inductor serves as an impedance adjustment, so that the output of the impedance can be changed and in accordance with the desired (match).

2.3 Transistor

Transistors have two connections, one of which is the emitter and the other base and collector. Because this is a transistor as two diodes. ransistor C1970 type normally used to raise the voltage 0.8 to 1 watt, I think it was in the C1970 study could increase about 8 times.On the C1971 transistor can be coupled directly from the exciter circuit and the voltage of 6.5 to 7 watts or bias raised about 10 times.If the C1970 to C1971 join the output power of about 12 watts or more. (All will be explained in Chapter III)

2.4 ExciterExciter circuit consists of an oscillator and buffer.•  OscillatorTransmitter is the core of an oscillator. To be able to build a good communication system should begin with an oscillator that can work perfectly. In the communication system, the oscillator generates a sine wave is used as the carrier signal. Then the information signal is superimposed on a carrier signal with the modulation process.•  Buffer (Buffer)All types of oscillators require a buffer. Buffer serves to stabilize the frequency and / or amplitude of the oscillator from loading the next level. Usually a buffer consisting of 1 or 2 levels of the transistor amplifier dibias as class A.The heart of the broadcast transmitter FM exciter is located on it. Function of the exciter is to generate and modulate a carrier wave with one or more input (mono, stereo, SCA) in accordance with FCC standards. Which has been modulated carrier wave is then amplified by a wideband amplifier to the level required by the next level.

2.5 BoosterPower amplifier is more popularly known as Booster. Booster is a device mounted radio transmitters attached to and used to amplify radio frequency transmit power in any direction that you want to go. For example, for a transmitter power of 25 watts which include only a single village, Booster is used to transmit power to be 50 to 100 watts so it can besurrounding the district. Boosters are generally small squares connected by cable to the transmitter which he built.Power amplifier is divided into two. First, the power amplifier which amplifies the signal in one cycle, the best signal quality and harmonious. The second, which only reinforces the power amplifier input signal is less than half of the cycle and generate a wave that damaged the same frequency.

2.6 Antenna

Antenna function and simultaneously capture signals radiate radio wave radiation. The antenna is divided into two by the beam, ie• omnidirectional (all directions). This antenna radiates radio waves are equally strong all directions.• Bidirectional (both directions). This antenna radiates equally strong radio waves to only two directions. Two parameters that need to be considered is the polarization of the antenna and its gain. Put simply, an antenna has vertical polarization if the antenna is placed in a position perpendicular to the earth. Antenna with vertical polarization would produce radio waves with vertical polarization as well. In addition to the vertical, some horizontal polarized antenna, when the antenna is positioned parallel to the field of the earth.

2.7 Transmission LineTransmission line is the introduction to the generated power to the transmitter antenna. As an introduction to power, a good transmission line will not reduce the power of delivery and did not radiate, because it is the duty antennas radiate. So that the maximum power transfer occurs, then the transmission line characteristic impedance should also have the same view of resource load. Transmission line characteristic impedance is 300 W common (ribbon cable to the black and white TV), 75 W (on a color TV coaxial cable) and 50W (coaxial cable to the amateur radio equipment).Additional tools are in need in assembling a 12-watt FM transmitter, among which are:

•  Power MeterPower Meter is a tool to measure the wave. On a transmission line that is not worth it, but the waves come rolling waves are reflected. Wave dating from the source to the load direction (from transmitter to antenna), while the reflected wave from the opposite direction (from the antenna to the transmitter). Usually on the Power Meter has two scales, onecame to power and one for the reflected power. The reflected power scale to be smaller than the scale for the future.

•  SWR MeterSWR meter or measuring comparative standing waves are used to measure the ratio of the incident wave and reflected wave. So it is known how a resource commensurate with the burden. The working principle is based on the Power Meter SWR Meter. If there is only one Power Meter measurements, the SWR can be calculated from the incident power (Pf) andthe reflected power (Pr) with the formula:SWR = (OPF + ÖPr) (OPF - ÖPr).

• From the formula, the state equivalent (Pr = O) will be obtained SWR = 1.
• For a state that is not worth going to get SWR> 1.
• For the worst circumstances in which all power is reflected back dating (Pf = Pr) will get the SWR = infinity.

•  Dummy LoadTo be able to broadcast a maximum transmit power, but efficient, it takes a load impedance that is known with certainty as it is called Dummy Load reference. Dummy Load is free from the influence of frequency and can handle the disposal of the transmit power is too great. Dummy Load impedance is usually 50 or 75 Ohm. Dummy Load can be made withput some resistors in parallel in order to obtain the desired resistance and power. Parallelize some resistors minimize the stray inductance of the resistor. For example, can use the carbon resistor 300 Ohm / 2 watt for 6 seeds that are connected in parallel to get the Dummy Load with power of 12 watts and 50 Ohm impedance.

CHAPTER IIIPLANNING AND DEVELOPMENT TOOLS

3.1. PreliminaryTo plan and create a 12 Watt FM transmitter, need to know first about a block diagram of the system, the working system of the circuit isOverall, the calculations and planning.

3.2. System Block Diagram and Figure Series Overall

The picture above shows a block diagram of this system and imageThe overall network is made in full.Transmission System Block Diagram picture as a whole

3.2.1 Block diagram of the image transmitter exciter circuit FM

Picture Exciter Circuit Network consists of exciter oscillator and buffer. In this Exciter Network using the specification of components as follows:•  Koker•  Inductor: L2 = 0.12 micro-Henry, Henry Micro L3 = 0.12, L4 = 0.2 micro-Henry•  Transistor: C930•  Ohm: 5.6 K, 47 K, 33 K•  Babysitter WANTED: 2.2 nF, 100 nF, 18 pF, 20 pF, 5 pF•  trimer: 5-60 pFExciter is a network that produces oscillations, because the exciter are oscillator that acts as a sine wave generator and it will be dimodulasikan. In the oscillator system is also available buffer (buffer) that functions to stabilize the frequency / modulation oscillator amplifier due to the loading process by the next level.

3.2.2 Network Booster (Power Amplifier)

The series of images BoosterIn the Booster circuit uses components withthe following specifications:

•  Inductors: L1 = 0.2 micro-Henry. L2 = 0.2 micro-Henry. 0085 L3 = L4 = 0.04 micro micro Henry Henry. L5 = 0.1 micro-Henry. L6 = 0.2 micro-Henry L7 = 0.2 micro-Henry.

•  Transistor 1970: 10 V VCEIc 0.1 AΒ 10-180

•  trimer: 5-30 pFBooster circuit consists of two levels of transistor amplifiers, each working on a class C, each input and output transistor amplifier circuit is given impedance adjustment.Strengthening of the first transistor using C1970. Strengthening the circuit has a 9.2 dB power gain (8 times), so that from the exciter-power 0.25 W of power generated should be 2 W. In fact the output of this first level of reinforcement produces only 1.75 Watt power, this is due to the loss of matching network circuit.Strengthening of the second level using transistor C1971. The amplifier circuit has a 10dB power gain (10 times). So that the power of the first level of 1.75 W can be strengthened to 17.5 W. In fact strengthening the power of the second level only reached 12.5 Watt.

This is due to the loss of matching network and the limited range ofC1971 transistor. Because the price of the C1971 transistor is relatively expensive it is to use only the C1970 transistor. Therefore, the power generated by the transmitter is not as high as 12 Watt. Because of the heat generated second transistor is large enough then we put enough cooling.

CHAPTER IVTESTING TOOLS4.1

GeneralThis chapter discusses the testing and analysis system that has been made. In general, this test aims to determine if the device has been realized that can be worked in accordance with a predetermined plan specifications. The purpose of the tests performed on the system are as follows:

•  Knowing how the exciter circuit

•  Knowing how the booster circuit

4.2 Testing exciter circuit
•  The purposeTo find out if the oscillator can work well and achieve the desired frequency. And also to determine whether the buffer is running properly.
•  The equipment usedA. Koker2. Inductor3. Transistor4. Resistor5. Trimer6. Dummy Load7. 5 volt power supply8. Multimeter9. Frequency Counter10. PCB
•  The test procedureTest Block DiagramA. Assemble the equipment used in accordance Picture2. Provide 12 volt power supply to the exciter circuit3. Switch the exciter circuit to get the most power in large4. Calculate the voltage at TP 1, TP 2 and, TP 35. Observe the output (at V output)
•  The test resultsThe test results are shown in Table. the following:Exciter circuit Testing ResultsTest Results PointA 0.6V2 0.6V3 11.75 V
4.3 Testing a series of booster
•  The purposeTo gain greater power and also increase the distance range of further emission up to 7-fold.
•  The equipment usedA. Inductor2. Transistor3. Trimer4. Dummy Load5. 12 Volt Power Supply
•  The test procedureTesting Block Diagram Picture Booster:A. Assemble the equipment used in accordance Picture2. Large test circuit voltage that can be accepted3. Observing the output
•  The test resultsThe test results are shown in Table. the following:Booster circuit Testing ResultsTest Results Point4 11,755 11,75

CHAPTER VCLOSING
5.1. ConclusionBased on the test results it can be concluded:
•  In a series of FM transmitters weve made, the power output is only 2 Watt for C1970 transistor used is that only 1 Watt power up
•  FM transmitter that can be made only reach 93 MHz frequency
•  The distance achieved depends on the power emitted by the FM transmitter
5.2 Advice
• If you want to make the transmitter starts with a good oscillator.
• If you want to make a series of FM with a power greater then use the transistor C1971, C1946. the power generated about 25 watts.
• To balance the output of the FM transmitter mounted circuit PLL (Phase Local Loop).

Friday, October 17, 2014

A Simple Function Generator

This is a simple function generator circuit that can produce the following waveforms: square wave, triangular wave, and sine wave.

The circuits main components are two 1458 ICs. The 1458 is a dual op-amp IC, i.e., an IC that houses two op amps inside it. The circuit uses four op amps, two from each 1458.

The bottom-most op amp in Figure 1 is configured as an astable multivibrator, which continuously generates a square wave. Assume that C1 has no charge initially. The voltage at the inverting input is zero, while the voltage at the non-inverting input is very slightly positive (a ratio of the op amps output offset voltage as determined by R1 and R2). This minute voltage difference at the inputs is enough to cause the op amps output to swing to high.

When the output becomes high, C1 starts charging up. The voltage at the inverting input soon exceeds that at the non-inverting input, forcing the output to swing to low, which discharges C1 again. At a certain point, the voltage at the non-inverting input exceeds that at the inverting input again, and the output of the op amp goes high again.

This cycle wherein the first op amps output swings between low and high goes on indefinitely, generating the square wave.

The two middle op-amps are both configured as integrators. The input to the second op amp is the square wave output of the first op amp. Being configured as an integrator, this op amp outputs a triangular wave (the integral of a square wave), as shown in Figure 1.

The triangular wave output of the second op amp is then fed into the third op amp, which is also configured as an integrator. The output of the third op amp is a sine wave (the integral of a triangular wave).

The sine wave output of the third op amp is fed into the fourth op amp, which is configured as an inverting amplifier. The output of this last op amp is also a sine wave but opposite in phase as its input.

Monday, October 13, 2014

Boost up current to 8 Amps from a LM2575

Boost

The LM2575 works a regulator only and don’t deliver any current to the load.
If the regulator switches “ON”, you find a voltage at the output of it. This makes T4 switching on also.
The collector of T4 now is nearly GND and also the Gate of FET T3. This FET switches on (it’s a P-FET!)
For T3 you can take everything what’s called Power P-FET with low RDSON, a IRF9540 is a good choice.

The “invention” of this circuit is the Gate turn off of T3.
In ON State, The Gate of T3 has nearly GND potential, D9 conducts and T5 is off.
If now the Regulator switch it’s output OFF, then the Base of T4 is pulled low by R12 and no currents flow through T4.
Also the cathode of D9 is connected to Vcc via R13. The stored energy in the Gate capacity of T3 lets now pull T5′s emiter lower then the base. Whats happens if the Base of a NPN transistor has higher voltage than the emiter? It conducts ! Now, T3′s gate is directly connected to the source via T5 and the gate capacity can be discharged very fast.

Friday, September 26, 2014

How to Charge a Lead Acid Battery Circuit Diagram

Batteries should not be discharged below 1.8 volts per cell, as it can cause permanent damage to the cells.
A 40 ampere-hour battery when discharged at 4—ampere rate will take 40/ 4, i.e. 10 hours to be completely discharged. Suppose the same battery is discharged at 10—amperes rate. Theoretically, it should take 40/ 10, i.e. 4 hours to get fully discharged. But in practice it 1S observed that the battery will get fully discharged within about 3% hours itself In other words, the higher the discharge rate, the lesser will become the capacity of the battery.
A fully discharged battery needs to be charged about 1% times its full ‘capacity’, to reach a fully charged, state. In other words, a 40-AH battery being charged at 4 amperes rate will take 15 hours and not 10 hours to be fully charged Charging a partially discharged battery =· It is not possible to estimate the time needed to charge a partially discharged battery.
The charging or discharging of a battery is ideal at 10 hours rate, which means that a 40 ampere hour battery is to be charged or discharged at 40/ 10, i.e. 4-ampere rate.
Lead—acid battery has a voltage of 2.1 volts per cell (on load) when fully charged, which will rise up to 2.7 volts per cell while on charge. When the voltage per cell (on load) drops to 1.8 volts, the battery is considered to be fully discharged.
However, the battery may be charged till such time as the following are observed: (a) Free gassing of the cells. (b) Battery voltage reaches its maximum value, and remains steady. (c) The specific gravity of the electrolyte (as measured by a hydrometer) reaches 1.240
That’s why is engine starting, when the battery drains 200 to 300 amperes, the battery becomes dead’ within a few seconds of use.

How to charge a lead acid battery, circuit diagram

Tuesday, September 9, 2014

Build a Wire Break Alarm With Delay Wiring diagram Schematic

Here is a simple schema of wire-break alarm that activates after a delay of 15 to 30 seconds. When the thin-wire loop running across the entrance door is broken, the alarm sounds after a delay of 15 to 30 seconds, the time period set through VR1. Thus the occupants get sufficient time to lock the room from the outside and catch the thief.

The schema uses CD4060, which is a 14-stage ripple-carry binary counter/divider and oscillator. It is wired as a timer here and does not need input pulse for trigger. CD4060 gets activated as soon as the power supply is switched on. Output O13 of CD4060 goes high after the lapse of preset delay set through VR1. Transistor SL100 (T2) is wired as a switch to power the timer section built around CD4060. When the wire loop is closed, transistor T2 does not conduct. So power to the timer schema is not available and the piezobuzzer does not sound.

Wire-Break Alarm With Delay Circuit Schematic

On the other hand, when the wire loop is broken by some intruder, transistor T2 conducts to power the schema and the piezobuzzer sounds after 15 to 30 seconds. IC1 can be reset by connecting the wire loop or interrupting the supply. The schema works off regulated 9V-12V. Assemble it on a general-purpose PCB and enclose in a metallic or plastic box of appropriate size. Connect piezobuzzer PZ1 through external wires and complete the installation.

Friday, September 5, 2014

build a Low Cost Stereo Level Indicator

Usually, Low-Cost Stereo Level Indicator home stereo power amplifiers don’t have output level indicators. An output power level indicator can be added to each channel of these stereo power amplifiers. As low levels of the output power are not disturbing and damaging to the people, there is no need to add a preamplifier and low-level detector before IC LM3915. But you should know when the output power becomes considerably high.

Here we present a very simple, low-cost stereo-level indicator schema for home power amplifiers with power rating of around 0.5W. The schema is built around two LM3915 dot/bar display driver ICs (IC1 and IC2). LM3915 senses analogue voltage levels to drive ten LEDs, providing a logarithmic 3dB/step analogue display.

Stereo Level Indicator Circuit Diagram

The voltage levels below 1V are not important because these correspond to a low level of the audio signal. Similarly, input voltage levels above 30V correspond to too high levels of the output power, which are not applicable for home power amplifiers. So the voltage levels of our interest are 1V to 30V, which can be handled directly with LM3915. LM3915 needs no protection against ±35V inputs, which simplifies the schema.

Most audio power amplifiers can drive 2-ohm to around 32-ohm loads. A load of several kilo-ohms will not change the conditions for the amplifier. CON1 is the input connector and CON2 output connector for the loudspeaker or headphone. Each channel has its own LM3915 and ten LEDs to indicate the power level. To indicate the different audio levels, select LEDs of three colours as per your liking. For example, you can have five green LEDs, three yellow LEDs and two red LEDs.

If appropriate signal generators and measuring equipment are not available, the level indicator can be calibrated based on personal observations. For example, the audio signal should be in the green LEDs zone when the signal is strong enough but not irritating, in the yellow zone when it is disturbing or starting to get distorted, and in the red zone when it is heavily distorted or too strong to listen to in the room.

Calibration can be done with the help of potentiometers VR1 and VR2, which are optional. Switches S1 and S2 let you select between two modes of LM3915 operation—the bar mode and the dot mode. These too can be removed or replaced with jumpers, if not required. When the switches are removed, leave pins 9 of IC1 and IC2 open.

The schema works off regulated 12V. You can also power it through a 12V rechargeable battery.

Assemble the schema on a general-purpose PCB and enclose in a suitable cabinet. Fix all the LEDs in two rows on the front side of the cabinet. Also affix the two terminals for input and output on rear side of the cabinet. link

Monday, September 1, 2014

A Car Battery Monitor Wiring diagram Schematic

A close call on the road can really focus your mind on the importance of having a battery monitor in a car. I had been enjoying a pleasant week of travelling around the countryside at a leisurely pace and taking in the beautiful scenery each day. It wasnt until the final day, with the big rush to return home, that I had to drive at night.My home is deep in the country and on the road I was travelling the closest petrol station may be 80km away. I was travelling through an area that is full of open-cut coal mines and large heavily loaded semi-trailers constantly pound the roads, travelling at quite high speeds. It was around 8pm at night and everything was very dark no street lights or house lights anywhere.

Just as I was going up a hill, the lights began to dim and the engine coughed. A large semi-trailer loomed in the rear-vision mirror as I pushed the clutch in and tried to restart. My speed was falling rapidly and my lights were blacked out - I was like a sitting duck in the middle of the road, as the semi-trailer came rapidly bearing down on me. I just managed to pull the car off the road, as the semi-trailer came screaming past, missing me by inches! After calling for assistance from the NRMA, the problem was found to be a fault in the alternator, which was failing to charge the battery. The battery voltage had been falling under the heavy load of the lights and at the worst possible time, there was not sufficient power for the lights or the motor.

After the initial shock wore off, I put on my thinking cap to come up with a PIC-based solution to the problem. What was really needed was a display and a buzzer, to get my attention should the voltage fall outside a specified range. So my design criteria was set, a series of LEDs could indicate the voltage and a buzzer would also be used to warn of problems.

Main Features:

Visual indication of battery voltage
Audible warning when voltage becomes low
Screw terminals for easy connection
Simple and easy to build

Circuit details:

The schema is based on PIC16F819 18-pin microcontroller which has an analog-to-digital (A/D) input to monitor the battery voltage and outputs capable of driving LEDs directly, to keep the component count down. There are seven LEDs in all, giving a good range of voltage indication. The topmost LED, LED1, comes on for voltages above 14V which will occur when the battery is fully charged. LED2 indicates for voltages between 13.5V and 14V while LED3 indicates between 13V and 13.5V. Normally, one of these LEDs will be on. LED4 covers 12.5V to 13V while LED5 covers 12V to 12.5V. LED6 covers from 11.5V to 12V while LED7 comes on for voltages below 11.5V. These two LEDs are backed up by the piezo chime which beeps for voltages between 11.5V and 12V and becomes more insistent for voltages below 11.5V.

That might seem fairly conservative. After all, most cars will start with no troubles, even though the battery voltage might be a touch below 12V, wont they? Well, no. Some modern cars will happily crank the motor at voltages below 11V but their engine management will not let the motor start unless the voltage is above 11V. So dont think that a modern car will always start reliably. This little battery monitor could easily prevent a very inconvenient failure to start! So lets describe the rest of the schema. The incoming supply is connected via diode D1 which provides protection against reverse polarity while zener diode ZD1 provides protection from spike voltages.

A standard 7805 3-terminal regulator is then used to provide a stable 5V to the microcontroller. The battery voltage is sensed via a voltage divider using 33kΩ and 100kΩ resistors. This brings the voltage down to within the 0-5V range for the A/D input of the PIC16F819. Port B (RB0 to RB7) of the microcontroller is then used to drive the various LEDs, with current limiting provided via the 330Ω resistor network. RB7, pin 13, drives a switching transistor for the piezo buzzer.

Software:

For the software, the design follows the basic template for a PIC microcontroller. Port A and its ADC (analog-to-digital converter) function are set up while port B functions as the output for the LEDs and buzzer. Once the set-up is complete, a reading will be taken at port RA2, the input for the A/D convertor. This reading is then compared with a series of values to determine the range of the voltage. This is similar to a series of "if" statements in Basic language. If the voltage is found to be within a certain range, the relevant port B pin will be turned on. If the voltage is below 12V, the buzzer will be turned on for a brief period, to signal a low battery condition. As the voltage falls below 11.5V, the frequency of the beeps will increase, to signal increased urgency.

Building it:

All the parts are mounted on a small PC board measuring 46 x 46mm (available from Futurlec). The starting point should be the IC socket for the PIC16F819, as this is easiest to mount while the board is bare. The next item can be the PC terminal block. The resistors and capacitors can then follow. Make sure the electrolytics are inserted with correct polarity.

Make sure that you do not confuse the zener (ZD1) with the diode when you are installing them; the diode is the larger package of the two.

Even more important, dont get the 78L05 3-terminal regulator and the 2N3906 transistor mixed up; they come in identical packages. The 78L05 will be labelled as such while the 2N3906 will be labelled "3906". And make sure you insert them the correct way around. The buzzer must also be installed with the correct polarity. The 330Ω current limiting resistors are all in a 10-pin in-line package. There are four green LEDs, two yellow and one red. They need to be installed in line and with the correct orientation.

Testing:

Before you insert the PIC16F819 microcontroller, do a voltage check. Connect a 12V source and check for the presence of 5V between pins 14 & 5 OF IC1. If 5V is not present, check the polarity of regulator REG1 and the polarity of the diode D1. If these tests are OK, insert the IC and test the unit over a range of voltage between 9V and 15V. Make sure that all LEDs come on in sequence and the piezo buzzer beeps for voltages below 12V.

Now it is matter of installing the unit in your car. It is preferable to install the unit in a visible position for the driver. However, it should not obscure any other instruments. The unit should be connected to the cars 12V supply after the ignition switch. This will turn the unit off with the other instruments and prevent battery drain while the motor is not running.

Author :Alan Bonnard

Thursday, August 28, 2014

Running Light circuit uses a CMOS 555 timer

A Transcutaneous Electrical Nerve Stimulation (TENS) device is, put bluntly, a machine for giving electric shocks. The author was prescribed such a device on loan by his orthopaedic specialist. The unit has a large number of programmes, of which he used only one. Measuring the signals at the output of the device in this mode revealed damped oscillations at a frequency of approximately 2.5 kHz, with a repetition rate of approximately 100 Hz.

Running Light circuit uses a CMOS 555 timer

How hard can it be to make such a device ourselves? The simple circuit uses a CMOS 555 timer to produce a brief pulse which feeds a 1:10 miniature transformer. Together with a 4.7 nF capacitor the transformer makes a parallel resonant circuit: the resonance leads to a considerable increase in the output voltage. The pulse width can be adjusted using a potentiometer, here shown combined with the on-off switch. Wider pulses produce higher output voltages. Since a peak voltage of up to 200 V can be produced, the transformer must have adequate insulation: Conrad Electronics type 516260-62 is suitable. A low-cost phono socket at the output gives reliable connection to the electrode cable.

The adhesive electrodes shown in the photograph (disposable and permanent types are available) can be obtained from pharmacies and medical suppliers. They generally have connectors compatible with 2 mm banana plugs, and so it is possible to make up the necessary cable yourself. To treat responsive parts of the body, such as the arm, the potentiometer need not be turned up far to obtain the necessary sensation. Less sensitive parts, such as the knee or foot, need a rather higher voltage and hence a correspondingly higher potentiometer setting.

Author: Klaus Rohwer – Copyright: Elektor Electronics Magazine

Link:http://www.extremecircuits.net/2010/06/transcutaneous-electrical-nerve_03.html

Wednesday, August 27, 2014

Build a 5V Supply Wiring diagram Schematic

This 5V Supply Circuit Diagram protects microprocessor systems from `brownouts` without the expense of an uninterpretable power supply. Designed around a small 9-V nickel cadmium battery the schema continues to provide a constant 5-V output during brownouts of up to a few seconds. Load currents of up to 500 mA may be drawn using the components shown.

With this mains-derived supply present, D5 is forward biased so that the stabilized supply powers the 5-V regulator and hence the schemary to be protected. FET Tj is held on by Dl, its drain current being provided from the dc supply via Rb and D2. Diode D3 is reverse-biased so that T2 is off, and the battery is isolated from D6. RCH and D4 serve to trickle charge the battery with approximately 1.2 mA.

5V Supply Circuit Diagram

When the 12-V supply is removed, Rl and Cl initially keep Tl switched on. D3 is now forward biased, so that Tl drain current is drawn via Rb, D3 and T2 from the battery. This switches T2 on, allowing the load schemary to draw current from the battery via D6 and the 5-V regulator. After a few seconds Cl has discharged (via Rl) such that Vgs falls below the threshold value for the FET, and Tl switches off. There is then no path for T2 base current, so that it also switches off, isolating the battery.

Build a Power supply Protection Wiring diagram Schematic

Why Build a Power supply Protection Circuit Diagram. When using a regulated supply to reduce a supply voltage there is always the danger of component failure in the supply and consequent damage to the equipment. A fuse will protect when excess current is drawn, but might be too slow to cope with over voltage conditions. The values shown are for a 12 V supply being dropped to 5 V.

Power supply Protection Circuit Diagram

The trip voltage is set to 5.7 V to protect the equipment in the event of a regulator fault. The 330 ohm resistor and the 500 ohm potentiometer form a potential divider which samples the output voltage as set by adjustment of the potentiometer. The SCR is selected to carry at least twice the fuse rating. The full supply voltage is connected to the input of the regulator.

The 2N2906 is held bias off by the 10 k resistor and the SCR so that the LED is held off. If the output voltage rises above a set trip value then the SCR will conduct, the fuse will blow, and the 2N3906 will be supplied with base current via the 10 k resistor, and the LED will light up.

Tuesday, August 26, 2014

Build a FM Booster Wiring diagram Schematic

A low-cost schema of an FM booster that can be used to listen programs from distant FM stations clearly. The schema comprises a common-emitter tuned RF preamplifier wired around VHF/UHF transistor 2SC2570 ( C2570). this FM booster schema is constructed using few common components( not require some special components ) and provide a very good gain .to calibrate this schema you need to adjust input/output trimmers (VC1/VC2) for maximum gain.

FM Booster Circuit Diagram Circuit Diagram

Input coil L1 consists of four turns of 20SWG enamelled copper wire (slightly space wound) over 5mm diameter former. It is tapped at the first turn from ground lead side. Coil L2 is similar to L1, but has only three turns. Both of the trimmers are 22pF value. This FM radio signal booster needs to be powered by a 12 volts DC power supply .

Monday, August 25, 2014

How to make a simple motor

This is a simple moter schema.These pictures show how to make a simple motor.first of all you should take two plates that I have mentioned bellow.and set it up on a wooden plate as picture 3 has shown.Then after take coils and wrap it around the plastic stick. When the stick rotates the coil should have a contact with the current supplier so after wrapping place the coil as picture shows.place a magnet middle of the stick as picture shows.