Showing posts with label controlled. Show all posts
Showing posts with label controlled. Show all posts
Saturday, March 23, 2013
Radio Controlled Electronic Flash
A radio controlled electronic flash is a useful item in any photographers kit. Professionals use them all the time. For example, a wedding photographer would put one behind the bride to back-light her gown and veil. You dont want wires showing in a shot like that. To build this control you will need an old R/C car (the simplest sort) in which the car runs in reverse at switch-on and goes ahead only when the remote is operated. They can be picked up cheaply as school fetes and garage sales. A typical car will run from 3V (two cells) and use 9V in the transmitter.
Before proceeding, make sure that the electronics in the car are operating. It doesnt matter if the wheels are broken or the motor is dead. You need to gain access to the leads to the motor. Normally (ie, without the remote operating), one is positive with respect to the other. Label them accordingly. On pressing the remote button, the polarity of the motor leads should swap. You will also need a flash extension cord you can cut into two sections. At the transmitter, the camera end of the extension cord is fed into the case and soldered to the control button contacts, as shown in Fig.1.
The contacts are in series with the battery supply, so if you dont want to open the transmitter, just cut one of the battery leads and connect the flash extension cord into the gap so created. You will then need to tape down the remote button so that it is permanently operated (ie, closed). All that needs to be done at the receiver end is to connect the normally negative motor lead to the gate circuit of an SCR, as shown in Fig.2, while the normally positive lead goes to the cathode of the SCR. Now, when the transmitter is operated by the cameras contacts, the lead polarity is reversed and the SCR acts as a switch to fire a portable electronic flash via the other half of the flash extension cord.
The transmitter can be attached to the camera via a flash bracket or a screw into the tripod socket, depending on what is the most convenient arrangement. The added components in the receiver can be mounted on Veroboard and housed in the space where the electric motor was. If appearance is a primary consideration, the receiver and the added components could be mounted in a standard jiffy box.
Before proceeding, make sure that the electronics in the car are operating. It doesnt matter if the wheels are broken or the motor is dead. You need to gain access to the leads to the motor. Normally (ie, without the remote operating), one is positive with respect to the other. Label them accordingly. On pressing the remote button, the polarity of the motor leads should swap. You will also need a flash extension cord you can cut into two sections. At the transmitter, the camera end of the extension cord is fed into the case and soldered to the control button contacts, as shown in Fig.1.
The contacts are in series with the battery supply, so if you dont want to open the transmitter, just cut one of the battery leads and connect the flash extension cord into the gap so created. You will then need to tape down the remote button so that it is permanently operated (ie, closed). All that needs to be done at the receiver end is to connect the normally negative motor lead to the gate circuit of an SCR, as shown in Fig.2, while the normally positive lead goes to the cathode of the SCR. Now, when the transmitter is operated by the cameras contacts, the lead polarity is reversed and the SCR acts as a switch to fire a portable electronic flash via the other half of the flash extension cord.
The transmitter can be attached to the camera via a flash bracket or a screw into the tripod socket, depending on what is the most convenient arrangement. The added components in the receiver can be mounted on Veroboard and housed in the space where the electric motor was. If appearance is a primary consideration, the receiver and the added components could be mounted in a standard jiffy box.
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.
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
T1 = TIP127
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