wiring and diagram

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Friday, January 10, 2014

Build a 200Ma 12v ni cad Battery Charger Circuit Diagram

This 200Ma-12v ni-cad Battery Charger Circuit Diagram charges the battery at 75 mA battery can be left in the charger indefinitely, until the battery is charged, then it reduces the To set the shut-off point, connect a 270-ohm, current to a trickle rate

It will completely 2-watt resistor across the charge terminals and recharge a dead battery in four hours and the adjust the pot for 15 volts across the resistor.

200Ma-12v ni-cad Battery Charger Circuit Diagram

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Wednesday, September 25, 2013

A Bedside Lamp Timer Circuit

30 minutes operation, Blinking LED signals 6 last minutes before turn-off

The purpose of this circuit is to power a lamp or other appliance for a given time (30 minutes in this case), and then to turn it off. It is useful when reading at bed by night, turning off the bedside lamp automatically in case the reader falls asleep... After turn-on by P1 pushbutton, the LED illuminates for around 25 minutes, but then it starts to blink for two minutes, stops blinking for two minutes and blinks for another two just before switching the lamp off, thus signaling that the on-time is ending. If the user want to prolong the reading, he/she can earn another half-hour of light by pushing on P1. Turning-off the lamp at users ease is obtained by pushing on P2.

Circuit diagram:

A Bedside Lamp Timer Circuit Diagram

Parts:

Resistors
R1 = 1K
R2 = 4K7
R3 = 10M
R4 = 1M
R5 = 10K

Capacitors
C1 = 470µF-25V
C2-C4100nF-63V

Semiconductors
C1 = 470µF-25V
C2-C4 = 100nF-63V
D1-D4 = 1N4002
D5 = 5mm. Red LED
IC1 = CD4012
IC2 = CD4060
Q1 = BC328
Q2 = BC547

Miscellaneous
P1,P2 = SPST Pushbuttons
T1 = 9+9 Volt Secondary 1VA Mains transformer
RL1 = 10.5V 470 Ohm Relay with SPDT 2A 220V switch
PL1 = Male Mains plug
SK1 = Female Mains socket

Circuit operation:
Q1 and Q2 form an ALL-ON ALL-OFF circuit that in the off state draws no significant current. P1 starts the circuit, the relay is turned on and the two ICs are powered. The lamp is powered by the relay switch, and IC2 is reset with a positive voltage at pin 12. IC2 starts oscillating at a frequency set by R4 and C4. With the values shown, pin 3 goes high after around 30 minutes, turning off the circuit via C3. During the c6 minutes preceding turn-off.

The LED does a blinking action by connections of IC1 to pins 1, 2 & 15 of IC2. Blinking frequency is provided by IC2 oscillator at pin 9. The two gates of IC1 are wired in parallel to source more current. If required, a piezo sounder can be connected to pins 1 & 14 of IC1. Obviously, timings can be varied changing C4 and/or R4 values.

Source : www.extremecircuits.net

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Monday, March 18, 2013

Controlling Motor with a Cell Phone Circuit Diagram Explained

The following article describes a very simple circuit idea which can be used for controlling a motors rotational direction i.e. for moving it either clockwise or anticlockwise through alternate miss calls from your cell phone.

I have already discussed a novel cell phone controlled remote switch circuit where the unit can be used for switching an electrical gadget through the users cell phone. The user just has to call the remote system which responds to the blank calls and generates the required alternate switching of the connected gadget.

The same circuit has been used here also, the output is appropriately modified such that now the unit becomes suitable for toggling the rotation of a DC motor.

The circuit shown below can be used for controlling a motor rotational direction, lets try to understand its functioning details:

The lower section of the diagram consisting of T1, T2, T3 and T4 along with the associated components forms a simple high gain audio amplifier circuit.

This circuit is used for amplifying the ringtone generated by the attached modem cell phone unit.

The modem cell phone handset is an ordinary NOKIA 1280 cell phone which is permanently integrated with this circuit.

The above modem cell phone uses a prepaid SIM card and thus it becomes a self contained receiver module.

When this modem cell phone is called by the owners cell phone, its ringtone activates and gets amplified by the above explained tone amplifier stage.

The amplified signal becomes powerful enough to triggers the relay RL1.

This relay holds or remains activated as long as the call stays connected, and breaks when the call is disconnected.

RL1s N/O contact is supplied with a 12v trigger to the adjoining stage which is a FLIP/FLOP stage, made by using four NAND gates from the IC 4093.

With every alternate missed calls from the owners cell phone, the modem cell phone signals the tone amplifier, which activates RL1, and RL1 in turn flips or flops the IC1 circuit.

The output of the flip flop is connected with a relay driver circuit which is attached with two relays RL2 in parallel. You may use a single DPDT relay also for better convenience.

The contacts of the relays are configured in such a manner that flipping them produces opposite movements for the motor thats integrated to them.

The mains supply to the relay and the motor is taken from RL1, which means the motor flips with every subsequent "missed calls" and remains activated until the call stays connected, and then halts.

The circuit can be modified in many different ways as per the users specifications.

The modem cell phone should be appropriately assigned with a particular continuous ringtone while the default ringtone should be assigned to "empty", tis will make the unit immune to unknown numbers or wrong numbers, and the owner will be the sole controller of the attached circuit and the motors.

Parts List

All resistors are 1/4w 5% CFR unless otherwise stated.

R1 = 22k
R2 = 220 OHMS
R3,R11,R12 = 100K
R4,R6,R7,R9 = 4.7K
R5 = 1K,
R8 = 2.2M
C1,C4,C5 = 0.22uF DISC TYPE
C2,C3 = 100uF/25V
T1,T2,T4,T5 = BC 547B
T3 = BC557 B
ALL DIODES = 1N4148
IC1 = 4093
RL1 = RELAY 12V/400 OHMS SPDT
RL2 = Relay DPDT 12V/400 ohms
L1 = small buzzer coil, small choke or similar.
JACK = 3.5mm AUDIO JACK
CELL PHONE MODEM = NOKIA 1280

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Converting a DCM Motor

We recently bought a train set made by a renowned company and just couldn’t resist looking inside the locomotive. Although it did have an electronic decoder, the DCM motor was already available 35 (!) years ago. It is most likely that this motor is used due to financial constraints, because Märklin (as you probably guessed) also has a modern 5-pole motor as part of its range. Incidentally, they have recently introduced a brushless model.

The DCM motor used in our locomotive is still an old-fashioned 3-pole series motor with an electromagnet to provide motive power. The new 5-pole motor has a permanent magnet. We therefore wondered if we couldn’t improve the driving characteristics if we powered the field winding separately, using a bridge rectifier and a 27 Ω current limiting resistor. This would effectively create a permanent magnet. The result was that the driving characteristics improved at lower speeds, but the initial acceleration remained the same. But a constant 0.5 A flows through the winding, which seems wasteful of the (limited) track power. A small circuit can reduce this current to less than half, making this technique more acceptable.

Circuit diagram :

Converting a DCM Motor Circuit Diagram

The field winding has to be disconnected from the rest (3 wires). A freewheeling diode (D1, Schottky) is then connected across the whole winding. The centre tap of the winding is no longer used. When FET T1 turns on, the current through the winding increases from zero until it reaches about 0.5 A. At this current the voltage drop across R4-R7 becomes greater than the reference voltage across D2 and the opamp will turn off the FET. The current through the winding continues flowing via D1, gradually reducing in strength. When the current has fallen about 10% (due to hysteresis caused by R3), IC1 will turn on T1 again. The cur-rent will increase again to 0.5 A and the FET is turned off again. This goes on continuously.

The current through the field winding is fairly constant, creating a good imitation of a permanent magnet. The nice thing about this circuit is that the total current consumption is only about 0.2 A, whereas the current flow through the winding is a continuous 0.5 A.

We made this modification because we wanted to convert the locomotive for use with a DCC decoder. A new controller is needed in any case, because the polarity on the rotor winding has to be reversed to change its direction of rotation. In the original motor this was done by using the other half of the winding.

There is also a good non-electrical alter-native: put a permanent magnet in the motor. But we didn’t have a suitable magnet, whereas all electronic parts could be picked straight from the spares box.

Source By : Streampowers

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Sunday, March 17, 2013

Make a 6v 4ah Automatic Battery Charger Circuit without Using a Relay

this is diagram a 6V 4.5 AH battery charger circuit which is able to charge 6V 4.5 AH lead acid batteries. The schematic is very simple and using only few components. IC LM317T is the heart of the circuit. The circuit is automatic so when the battery will become full charge it will stop charging. These type of circuits are very useful for solar garden light and can also be used in other circuits like emergency led lamp etc. Use transformer 230 AC to 9V / 500mA.

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Friday, March 15, 2013

Charging a Small NiMh Battery from Air By Steven Chiverton

Mr. Steven has devised an ingenious way of collecting energy from the air and using it for various useful purposes like for charging small 9v NiMh battery, or for making high voltages etc. The experiments are indeed very intriguing and I definitely want to share them with you all, lets know more from Steven himself......

Thanks pal you are welcome to put my stuff up in your blog, at least its getting shared around.

Theres more yet to come including my nmh battery charger experiments powered from the sec tower output now remember this i integrated ideas i find on the net together to come up with these new experiments like the polarity indicator i modified it to use as a sec tower energy output indicator or tester and then theres a led power meter circuit from a talking electronics site,

I modified that to use the energy output from the tower to charge hv caps up to and still light an afremenko plug up to and charge my nmh battery to and then theres the free energy from air circuit same as the one featured on the inventors 3 youtube videos which is the same on the youtube video titled Teslas little secret, this circuit works wonders when integrated with others and soaks up more energy when placed next to the modified polarity indicator circuit which is now the sec power output tester or indicator
so you see, ideas and integrating one circuit into another is an ingenious way to come up with new ideas and experiments. and then theres the ac operated relay circuit originally used to allow ac to operate a dc relay so a small modification to it allows my to get more RF energy from the sec tower , the same circuit cannot step up the voltage fed into a transformer in reverse mode to get stepped up ac for some reason but it does great for RF voltage RF currents so that i integrated into the whole system , so its the way to go, find a circuit improve it upgrade it modify it and integrate it into other circuit ideas ,
If you think thats great i have video footage of experiments where i can use any transformer any way around as an em pick up via simple vlf receiver circuit and even relay coils and, even ignition coils with there internal soft iron shielding inside the can and around the coil. and when i play a cassette tape right up against the ignition coil the sound from the tape is EM induced right through that ignition coil and through the soft iron shielding and comes right out the VLF receiver circuits headphones , in other words i can listen to a radio through an ignition coil and its easy with relays to as the coil in it is my em pickup coil and thats interesting . and the same VLF receiver circuit allowed me to listen to the em RF energy from the sec exciter tower to its a hum a little slower than mains hum thats what i hear .

Getting Free Energy from Air

The first circuit is a slightly modified led power meter from a talking electronics site normally the led power meter is used to tune bugging devices to put out the peak power something like that, but after i modified it it now charges nickel metal hydride batteries fast when used with the sec coil towers output ive only tested this a few times so more needs to be done yet since it worked on a bread board. the next circuit is the free energy from air circuit with hv caps and another slightly modified led power meter with added afremnko plug and nmh battery.

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Thursday, March 14, 2013

Make a Simple Music Controlled Christmas Lights Circuit

Building your own music controlled Christmas lights may not be as difficult as it may appear to be. The article discusses two simple configurations which may be used to decorate a party hall. The first circuit employs colorful LEDs which when integrated to a music system, interestingly dances forward/backward in a sequential pattern with the applied music intensities. The second circuit involves mains powered incandescent lamps and produces the same results as above imitating and sequencing with the connected music peaks.

Imagine all those bouncing and dancing lights around you during party nights, shooting up and down with loud music beats, can definitely enhance the ongoing ambiance. Wanna like to build them at home. A couple of circuits that may be used as music controlled Christmas lights is neatly explained here

Any celebration or a festival is unthinkable without music and lights, especially when it’s a Christmas party an enhanced ambiance becomes an absolute necessity. Dazzling, flashing, strobing lights, we have all seen them pretty commonly during celebrations and festive occasions. However, involving music to lights or rather synchronizing the two together so that the lights flash and follow the music pattern can add entirely a new volume of excitement to the party mood.

Although the design may appear to be complicated but actually integrating the two parameters is very easy, obviously a bit electronic wiring may be involved.

In many of my previous articles I have discussed LED lights and circuits to illuminate them in many different decorative ways.

In this article we will discuss how to make arrays of LEDs and mains operated incandescent lamps move and shuffle in a to and fro motion in response to the applied music at its input.

The attached incandescent lamps may be arranged in rows and columns to produce highly pulsating lighting effect. The effects created by the light arrays responding to the music peaks can simply become a visual treat.

A couple of circuits that may be used as music controlled Christmas lights are discussed below. Let’s understand their functioning through the following explanation:

Image Credit: terenceruffle.co.uk

Parts List

All collector resistors are 1K,

All presets are 10K,

4 Nos NPN transistors are BC547B,

1 PNP transistor is BC557,

All diodes are 1N4007,

All Triacs are BT136,

Lamps, as per preference, not to exceed 200 watts each.

Circuit Description

The configurations are pretty straightforward, looking at the figure, we find that the first circuit involves simple transistor amplifier stages arranged in sequence.

Each stage is comprised of an NPN transistor whose base is rigged into a potential dividing network via a preset. Its collector handles the load in the form of LEDs whereas the emitters are connected to the ground potential through diode or diodes as the sequence is preceded.

Here, the diodes perform an important function of regulating the transistor bias voltage. Each diode will drop around 0.6 volts across itself and enables the subsequent transistor stages to conduct only as the music peaks tend to reach the appropriate values.

The presets also help to the above function and may be precisely held to positions such that each subsequent stage conducts gradually or sequentially with increasing music peaks.

An input PNP transistor is included to initially amplify the music level available across the speaker terminals sufficiently, so that the light sequencing variations can be optimized over a wider range.

The second circuit which controls mains operated incandescent lamps works quite similarly as above. However, here the voltage regulation through diodes and zeners is rather employed to the bases of the transistor instead of the emitters, because we don’t want the AC lamps also getting rectified and producing half the illumination.

The base of the each subsequent transistor is offered an incrementing potential drop through additions of more number of diodes and zeners, but practically it’s found that it’s absolutely not required, a single diode to each of the bases appears to do the job well as the actual setting of the sequencing pattern is effectively optimized through the presets itself.

The above explained music controlled Christmas lights circuits can be assembled over a piece of general purpose PCB and housed inside the associated amplifier cabinet and powered from there itself. The output connections to the lamps will however require attention and should be very carefully terminated to the lamps using good quality insulated PVC wires.

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Tuesday, March 12, 2013

Make a Workbench Multimeter With the IC 741

Testing and troubleshooting electronic project circuits requires a multimeter, so why not make the circuit of a homemade multimeter itself as your next electronic project. Interesting homemade circuits like an Ohmmeter, voltmeter, ammeter are discussed here using the IC 741 and just a few other passive components.

Although multimeters are available plentifully in the market today, but building your own homemade multimeter can be real fun. Moreover the attributes involved can become thoroughly useful for the future electronic circuit building and testing procedures.

Circuit Illustrations

A simple configuration for measuring DC voltages is shown below using the IC 741. A couple of resistors Rx and Ry are introduced at the input in a potential divider mode at the non-inverting pin #3 of the IC. The voltage to be measured is applied across the resistor R1 and ground. Through proper selection of Rx and Ry, the range of the meter can be varied and different voltages can be measured.

In case you want to measure alternating voltages then the circuit illustrated below can become useful. The wiring is similar to the above wiring, however the positions of Rx and Ry have changed and also a coupling capacitor comes into the scene at the inverting input of the IC. Interestingly the meter here is now connected across a bridge network enabling the meter to display the relevant AC potentials correctly.

Another circuit to measure Direct current or Amps using the IC 741 is shown below. The configuration looks pretty simple. Here the input is applied across the resistor Rz i.e. across the non-inverting input pin #3 of the IC and the ground. The range of the meter can be simply varied by changing the value of the resistor Rz.

Resistors are one of the most important passive components which inevitably become an integral part of every electronic circuit. A circuit may be virtually impossible to build without accompanying these amazing current controlling devices. With so many resistors involved, a possible fault can always be on the cards. Identifying them requires a meter – an Ohm meter. A simple design using the IC 741 is shown below just for the purpose.

Unlike most of the analogue designs which tend to have a rather non-linear behavior, the present design very efficiently tackles the problem to produce a perfectly linear response with the corresponding measurements. The range is pretty impressive, it can measure values of resistors right from 1K up to a staggering 10 M. You may go on to modify the circuit for enabling the measurement of more extreme values.

The range is selected by moving the rotary switch switch into the relevant positions. Calibreating th instrument is simple and is done with the following points:

Adjust the selector switch to the “10K” position.

Trim the base preset of the transistor until its emitter voltage shows exactly 1 volt (measure using a digital multimeter.)

Next, Fix an accurately known 10 K resistor into the measuring slot.

Adjust the trimmer associated with the moving coil meter until the meter shows a full scale deflection.

All the circuits discussed above use dual supply voltages. The meter used is a moving coil type and is specified as 1mA FSD.

The preset across the pins 1, 4 and 5 of the IC 741 used for this homemede multimeter is used for adjusting the initial condition meter to exactly zero.

Relevant Values of Rx and Ry

The following are the values of the resistors required for varying the range of the respective meters.

DC Voltmeter

Rx--------------------Ry--------------------Meter FSD

10M-----------------1K--------------------1 KV

10M-----------------10K-------------------100V

10M-----------------100K------------------10V

900K----------------100K------------------1V

NIL-------------------100K-----------------0.1V

DC AMMETER

Rz--------------------Meter FSD

0.1-------------------1A

1---------------------100mA

10-------------------10mA

100-----------------1mA

1K-------------------100uA

10K-----------------10uA

100K---------------1uA

AC VOLTMETER

Ry---------------------Rx-------------------Meter FSD

10K-------------------10M----------------1KV

100K-----------------10M----------------100V

1M-------------------10M-----------------10V

1M--------------------1M------------------1V

1M--------------------100K----------------100mV

1M--------------------10K------------------10mV

1M--------------------1K--------------------1mV

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Make a Battery Charger Circuit in 15 Minutes

I have posted many battery charger circuits in this site, some are easy to build but less efficient, while some are too sophisticated involving complex construction steps. The one posted here is possibly the easiset with its concept and also is extremely easy to build. In fact if you had all the required material you would build it within 15 minutes of time.

The concept is indeed hugely simple and therefore pretty crude with its going. This means that though this idea is too simple, would require appropriate monitoring of the charging conditions of the battery, so that it does not get over charged or damaged.

To make this simplest battery charger circuit quickly, you would require the following bill of materials:

One rectifier diode, 1N5402

An incandescent bulb, having voltage rating equal to the battery which needs to be charged and current rating close to 1/10th of the battery AH.

A transformer having voltage rating equal to twice that of the battery voltage and current twice the charging rate of the battery. That means if the battery is 12V, the transformer should be 24V, and if the AH of the battery is 7.5 then dividing this by 10 gives 750mA which becomes the recommended charging rate of the battery, multiplying this by 2 gives 1.5Amps, so this becomes the required current rating of the transformer.

After you have collected all the above material, you may simply connect the above parameters together with the help of the diagram.

The functioning of the circuit may be explained in the following manner:

When the power is switched ON, the 1N5402 diode rectifies the 24V DC to produce half wave 24V DC at the output.
Though the RMS value of this voltage may appear to be 12V, the peak voltage is still 24V, therefore it cannot be applied directly to the battery.

To blunt of this peak value, we introduce a bulb in series with the circuit. The bulb absorbs the high peak values of the voltage and provides a relatively controlled output to the battery, which becomes self regulatory through the glow of the filament intensity of the bulb (varying resistance).

The voltage and current thus automatically becomes adjusted to appropriate charging levels which becomes just suitable for the battery safe charging.

The charging of the battery can be witnessed by the gradual dimming of the bulb as the threshold charging voltage of the battery is reached.

However once the battery voltage reaches close to 14.5V, the charging must be stopped, irrespective of the bulb glow condition.

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How to Make a Non Contact AC Mains Phase Detector – Measure AC Field Strength Wirelessly

The circuit discussed in this article is of a non-contact mains AC field detector which displays the presence of a mains AC field from a distance of more an 6 inches. The circuit can be used for locating faults in house wiring without the need of making physical contact with the inner conductor of the wire and becomes useful in locating the breaks in a wire by pin pointing the area where the AC mains may be blocked due to a breakage.

The circuit is basically high gain non inverting amplifier which is configured using a few opamps and a few other inexpensive passive electronic components.

Just a couple of opamps have been incorporated here from the IC 324 for the required operations.

Looking at the figure we notice the following things:

The non-inverting input of the IC is grounded making the sensitivity of the configuration to the maximum.

Similarly a feed back loop created by connecting the output of the opamps to the inverting input helps to increase the gain of the set up many folds.

The input is applied to the inverting input 2 of the IC through a blocking capacitor.

The signals entering via the antenna is quickly picked up by the opamp inverting input and sent to the preceding circuit for the required processing and amplification.

It may be interesting to note that the sensitivity of the design can be simply varied by changing the value of the feedback resistor R1, for maximum sensiticity this resistor can be omitted.

However this can make the circuit a bit unstable and might provide false results.

The next stage includes another identical amplifier which is just the repetition of the previous input stage. This stage has been included in order to make the response of the circuit instant and so that the circuit is able to pick even the slightest of RF or the AC field within a certain range.

In case the circuit is intended to be used for detecting mains phase only at touching proximities, the sensitivity may be reduced to the required levels or the second stage may be excluded from the design.

The LED connected at the output is used for displaying the presence of the AC field; an illuminated LED identifies the presence of the field while no light from it provides the opposite conclusion.

By connecting a 1V FSD moving coil meter at the output, the device can be used to detect and measure the average strength of the AC mains present in that particular vicinity.

Parts List

R1 = 2M2,

R2 = 100K,

R3 = 1K,

C1 = 0.01uF

A1, A2 = IC 324

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Monday, March 11, 2013

How to Build a Simple Room Temperature Monitor Circuit

A very simple yet highly precise air temperature sensor gauge circuit has been presented here. The use of the highly versatile and accurate IC LM 308 makes the circuit respond and react superbly to the smallest temperature changes happening over its surrounding atmosphere. Diode 1N4148 is used as an active ambient temperature sensor here.

The electronic air temperature sensor gauge circuit presented here is very accurate in its function, categorically due to its minimum level of hysteresis. Complete circuit description and construction clues included herein.

Circuit Description

The present circuit of an electronic air temperature sensor gauge circuit is outstandingly accurate and can be very effectively used to monitor the atmospheric temperature variations. Let’s briefly study its circuit functioning:

Here as usual we use the very versatile “garden diode” 1N4148 as the sensor due to its typical drawback (or rather an advantage for the present case) of changing its conduction characteristic in the influence of a varying ambient temperature. The diode 1N4148 is comfortably able to produce a linear and an exponential voltage drop across itself in response to a corresponding increase in the ambient temperature. This voltage drop is around 2mV for every degree rise in temperature. This particular feature of 1N4148 is extensively exploited in many low range temperature sensor circuits.

Referring to the figure we see that, IC1 is wired as an inverting amplifier and forms the heart of the circuit.

Its non inverting pin # 3 is held at a particular fixed reference voltage with the help of Z1, R4, P1 and R6.

Transistor T1 and T2 are used as a constant current source and helps in maintaining higher accuracy of the circuit.

The inverting input of the IC is connected to the sensor and monitors even the slightest change in the voltage variation across the sensor diode D1. These voltage variations as explained, is directly proportional to the changes in the ambient temperature.

The sensed temperature variation is instantly amplified into a corresponding voltage level by the IC and is received at its output pin #6.

The relevant readings are directly translated into degree Celsius through a 0-1V FSD moving coil type meter.

Parts List

R1, R4 = 12K,

R2 = 100E,

R3 = 1M,

R5 = 91K,

R6 = 510K,

P1 = 10K PRESET,

P2 = 100K PRESET,

C1 = 33pF,

C2, C3 = 0.0033uF,

T1, T2 = BC 557,

Z1= 4.7 V, 400mW,

D1 = 1N4148,

IC1 = LM308,

General Purpose Board as per size.

B1 and B2 = 9V PP3 battery.

M1 = 0 – 1 V, FSD moving coil type voltmeter

Setting Up the Circuit

The procedure is a bit critical and requires special attention. To complete the procedure you will need two accurately known temperature sources (hot and cold) and an accurate mercury-in-glass thermometer.

The calibration may be completed through the following points:

Initially keep the presets set at their midways. Connect a voltmeter (1 V FSD) at the output of the circuit.

For the cold temperature source, water at about room temperature is used here.

Dip the sensor and the glass thermometer into the water and record the temperature in the glass thermometer and the equivalent voltage outcome in the voltmeter.

Take a bowl of oil, heat it to about 100 degrees Celsius and wait until its temperature stabilizes down to about 80 degrees Celsius.

As above, immerse the two sensors and compare them with the above result. The voltage reading should be equal to the temperature change in the glass thermometer times 10 mill volt. Didn’t get it? Well, let’s read the following example.

Suppose, the cold temperature source water is at 25 degrees Celsius (room temperature), the hot source, as we know is at 80 degrees Celsius. Thus, the difference or the temperature change between them is equal to 55 degrees Celsius. Therefore the difference in the voltage readings should be 55 multiplied by 10 = 550 mill volts, or 0.55 volts.

If you don’t quite get the criterion satisfied, adjust P2 and continue to repeat the steps, until finally you achieve it.

Once the above rate of change (10 mV per 1 degree Celsius) is set, just adjust P1 so that the meter shows 0.25 volts at 25 degrees (sensor held in water at room temperature).

This concludes the setting of the circuit.

This air temperature sensor gauge circuit can also be effectively used as an electronic room thermometer unit.

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Cheap Emergency Light Circuit Diagram Using a Flashlight Bulb

Though its the world LEDs today, an ordinary flashlight bulb can also be considered a useful light emitting candidate especially because its much to configure than an LED.

The shown circuit diagram is quite simple to understand, a PNP transistor is used as the primary switching device.

A straight forward power supply provides the power to the circuit when mains is available.

As long as power is present, the transistor T1 remains positively biased and therefore remains switched OFF.
This inhibits battery power from entering the bulb and keeps it switched OFF.

The mains power is also utilized for charging the involved battery via the diode D2 and the current limiting resistor R1.

However, the moment AC mains fails, T1 is instantly forward biased, it conducts and allows the battery power to pass through it, which ultimately turns ON the bulb and the emergency light.

The entire unit may be adjusted inside a standard AC/DC adapter box and plugged IN directly in to an existing socket.

The bulb should be kept protruding outside the box so that the illumination reaches the external surrounding amply.

The moment AC mains fails,

Cheap Emergency Light Using a Flashlight Bulb Circuit Diagram

Parts List

R1 = 470 Ohms,

R2 = 1K,

C2 = 100uF/25V,

Bulb = Small Flashlight Bulb,

Battery = 6V, Rechargeable Type,

Transformer = 0-9V, 500 mA

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Sunday, March 10, 2013

How to Build a Simple PWM Controlled DC to DC Cell Phone Charger Circuit – Science Fair Project

The explained circuit can be easily made at home by any school kid and used for displaying in his science fair exhibition. The circuit is a simple cell phone charger that may be operated in conjunction with any DC source, from a car or a motorcycle battery or from any ordinary 12 V AC DC adapter.

Nowadays we find most of the vehicles have their in built cell phone battery charger units which surely becomes very handy for travelers who mostly remain outdoors travelling in their vehicle.

The proposed cell phone charger circuit is as good as the conventional chargers which come fitted inside the cars and bikes.

Moreover the circuit can be simply integrated to ones own vehicle if the feature is not originally available in the vehicle.

Alternatively one may think of manufacturing the present unit and selling them in the market as an automobile cell phone charger and earn some hard bucks.

Circuit Description

Cell phones as we all know are highly sophisticated gadgets by nature and when it comes to charging cell phones the parameters no doubt also needs to be of very high standards.

The AC/DC cell phone chargers which come with the cell phones are all SMPS based and are extremely good with their outputs and that’s why the cell phone gets so efficiently charged by them.

However if we try to make our own version, it may fail altogether and the cell phones may just not respond to the current and display a “not charging” on the screen.

Cell phone battery cannot just be charged by supplying DC 4 volts, unless the current is optimally dimensioned the charging won’t initiate.

Using voltage regulator IC for making a DC to DC charger, which I myself have discussed in one of my earlier article is a good approach, but the IC tends to become too hot while charging the cell phone battery and therefore requires adequate heatsinking for remaining cool and operative.

This makes the unit a bit bulkier and moreover some significant amount of power is wasted in the form of heat, so the design cannot be considered very efficient.

The present PWM controlled DC to DC cell phone charger circuit is outstanding in its respect because, the involvement of PWM pulses helps to keep the output very suitable to the cell phone circuitry and also the concept involves no heating of the output device, making the entire circuit truly efficient.

Looking at the circuit we find that again the work horse IC 555 comes to our rescue and performs the important function of generating the required PWM pulses.

The input to the circuit is supplied through some standard DC source, ideally from an automobile battery.

The voltage powers the IC which instantly starts generating the PWM pulses and feeds it to the components connected at its output pin #3.

At the output the power transistor is used for switching the DC voltage at its collector directly to the cell phone.

However only the average DC voltage is finally fed to the cell phone due to the presence of the 100uF capacitor, which effectively filters the pulsating current and provides a stable, standard 4 volts to the cell phone.

After the circuit is built, the two pots will need to be optimized perfectly so that a well dimensioned voltage is produced at the output which may be ideally suited for charging the cell phone.

Parts List

R1, R2, R3 = 1K,

P1, P2 = 47K,

C2 = 1n,

C3, C1 = 100uF/25V

IC1 = 555

D1, D2, D3 = 1N4007
T1 = TIP127

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How to Make a Ghost Detector Circuit

Do you believe in the existence of ghosts? Well some of you may answer positively while some may just nod their heads showing sheer skepticism regarding the issue. Whatever may be the reactions; nobody just can’t deny or ignore the responses delivered from the circuit explained in this article. Here we are discussing a super simple yet super sensitive paranormal activity sniffer circuit, which can be effectively and possibly used for detecting ghosts or similar supernatural existence within a range of 10 meters. Many of these circuits may be built and posted at definite intervals for securing a certain premise having a large area. The circuit incorporates an alarm at the output which sounds immediately on detecting a paranormal intrusion. The circuit is ideally suited for areas that are prone to ghosts or likely of getting infested with similar para-natural sneakers.

WARNING 1 – THE DEVICE HAS BEEN TESTED WITH POSITIVE RESULTS AND IS PROVED TO BE EXTREMELY ACCURATE WITH THE DISCUSSED DETECTIONS. FOLKS WITH WEAK HEARTS OR TENDER PERSONALITY ARE ADVISED NOT TO GO ABOUT WITH THIS DEVICE, BECAUSE THE DEVICE NOT ONLY DETECTS BUT ALSO COINCIDENTALLY HAS THE ABILITY OF ATTRACTING THE PARABEINGS.

WARNING 2 – THE DEVICE CAN BE TESTED IN MORGUES, GRAVEYARDS, cemeteries etc. ZOMBIES ARE THE ONES WHICH ARE INSTANTLY DETECTED BY THIS DEVICE EVEN FROM DISTANCES MORE THAN 50 METERS. NO DOUBT CREATURE LIKE ZOMBIES WILL HATE THIS DEVICE….BEWARE.

Concept

It has been found through experiments by many researchers that paranormal occupancy is strongly accompanied by RF disturbances ranging from a few Hertz to many Kilohertz.

These signals may be directly proportional to the hostile nature of the ghost. Zombies are found to be emitting the strongest signals and are therefore considered the most horrible among the lot.

The circuit of a ghost detector discussed here is typically configured for capturing the above RF emissions from these creatures and transforming them into more human understandable electronic indications.

Circuit Description

A single versatile IC 324 is involved in the whole operation.

The IC is a quad opamp IC, meaning four opamps in one package.

Referring to the figure, the opamps can be seen configured as hi gain non inverting amplifiers.

All the opamps are configured as high gain signal amplifiers.

Tiny electromagnetic or RF disturbances which are typically found being generated during the presence of ghosts or paranormal activities are instantly picked up by the antenna of the circuit and are fed to the input of the first opamp stage at pin #9.

The signals get instantly amplified and are transferred to the subsequent stages for further amplification and enhancement.

The output of the last opamp is connected to an opto-coupler.

The optocoupler is a homemade type, incorporating an LED and an LDR fixed such that their emitting and detecting surfaces are placed face to face inside a light proof enclosure.

Here, the optocoupler is used for sensing the LED illumination that may occur when a certain paranormal activity is sensed.

The illumination produced over the LED is tracked by the LDR whose resistance falls with the LED light.

The fall in the resistance of the LDR activates the connected transistor at the output, which in turn actuates a buzzer or a horn indicating a possible ghost intrusion.

The whole circuit may be built over a small piece of vero-board and should be strictly operated with a 9 volt battery.

The whole system may be enclosed inside a plastic box with the antenna kept protruding out of the box.

Parts List

R1 = 100K,

R2 = 2M2,

R3, R4 = 1K,
C1 = 0.01uF ceramic

OP1 = LED/LDR assembly inside a light proof enclosure,

T1 = BC557,

B1 = Piezo Electric Buzzer

READERS ARE REQUESTED TO SHARE THEIR EXPERIENCES WITH THIS DEVICE. A PHOTO OR A VIDEO PROOF WILL BE GREATLY APPRECIATED....

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Saturday, March 9, 2013

Make Yourself a Simple LED Flasher at Home

Looking for a simple LED project? Learn how easy it is to build a LED wig wag flasher using just a couple of transistors and few other passive components. A LED flasher schematic has also been provided to facilitate the ease of construction.

It’s a simple home fun project that will cost you hardly anything, yet the result will truly amuse you. Build a simple LED flasher and find ways to use it for decoration.

There you must have studied how a transistor can be used to switch a load connected to its collector through a small voltage applied to its base. The circuit of a simple LED wig wag flasher presented here incorporates just a couple of transistor and is wired as a multivibrator. The transistors alternately switch the LEDs connected to their collector points to produce an attractive flashing effect of LEDs. The circuit may also be used as an LED emergency flasher unit.

Parts Required

You will require the following very few numbers of components to build this circuit:

Resistors Â¼ watt, CFR, 5%

R1 and R2 = 22 K,

Potentiometers = 47 K,

LED series resistors are all = 150 Ohms,

LED RANDOM COLORED 5mm = 40 nos.

Capacitors Electrolytic Radial

C1 and C2 = 10 ÂµF / 25 Volts,

Transistors, General purpose

T2 and T2 = BC 547 B

General Purpose Board = Small piece 4” by 4”

How to Build a LED Flasher?

The construction of this LED flasher is very simple and is finished through the following simple steps:

In the given general purpose board, begin by inserting the two transistors somewhere around the centre of the board. Keep at least an inch of space in between them.

Solder and cut of their leads cleanly.

Next fill the board with the resistors and the capacitors. As above solder and cut their leads with the help of a nipper.

Now go on interconnecting their soldered leads as shown in the circuit diagram.

The entire procedure should take not more than Â½ an hour. This concludes the circuit board assembly.

Take a suitable plastic enclosure, drill appropriate holes for the potentiometers on its front panel.

Fix the potentiometers into these holes and connect them to the relevant points of the circuit board with the help of flexible wires as per the circuit schematic.

How to make the LED Series Connections?

To complete the LED string wiring just go through the following points:

In one of my previously written articles you can find a detailed discussion regarding the method of connecting the LEDs in series and then in parallel.

Just follow the circuit description of the article and complete the construction of two LED strings.

Or alternatively you may just do it as per the wiring diagram of the LED connections in this article itself.

Ultimately you will find that there are two negative points coming out of the two LED strings and a common positive.

How to Test it?

With the help of the given LED wig wag flasher schematic you may proceed the testing of the unit in the following manner:

Connect by soldering the LED string outputs to the appropriate points of the circuit board.

Finally connect a 12 supply to the completed circuit assembly, instantly the whole of the LED string will start flashing displaying a true fairy light effect.

This LED string light may be positioned appropriately over the wind shield of your car for a nice little decoration.

The potentiometer controls may be optimized as per your taste to get more amazing results from the circuit.

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Thursday, March 7, 2013

Discussing Adding a Capacitor at Inverter Outputs

Please read the previous post for the continuation...

Hi Ali,
The question is if the output stage is working with a square wave design, then why its not working with my design? After all my design is also producing square waves.

Unless I see the prototype myself I wont be able to say anything.

In the diagram I cant see any capacitors, which ones you are talking about? Capacitors across the windings can totally RUIN and sink the power output of an inverter transformer.

I think theres definitely something wrong with your assembly, I had also asked you regarding the mosfet heatsinks????

Regards.

Hi Swagatam, the one Cap across the pirmary input winding is 0.1uF 250V and the same across the output of the secondary winding.

I added these to act as filters. But ,Im just learning , so I could be wrong. They seem to work with the Square wave circuit. If Im wrong please correct me!!

I have also included a pic of the Heat Sink im using, its out of an old amplifier, its massive.
Theres also pics of the complete setup, I like to call my creation "Frank-Inverter" ! lol

Sincerely Ali

Continued HERE,

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