How to Make a Simple Piezo Buzzer Circuit Piezo Electric Buzzer Explained

In this article we will learn how to make a very simple piezo electric buzzer using hardly any electronic components. Just a single transistor, a coil, a piezo buzzer are enough to make it “buzz” or rather “twit” for you, with an output that may be quite ear piercing.

Circuit Description:

The buzzer circuit described here actually works in a quite unique way. Instead of the normal working concept employed by other forms of oscillators which require resistor and capacitor networks for generating the oscillations, this circuit use inductive feedback for the required operations.

Referring to the figure we find that the transistor T1 along with the inductor forms the heart of the circuit. Basically the coil which is specifically called the buzzer coil, is in fact positioned for amplifying the created oscillations while the actual feed back is provided by the center tap of the three terminal piezo element used for the present application.

When a voltage is introduced in the circuit, the transistor conducts, operating the piezo element across the buzzer coil, however this also leads to the grounding of the base of the transistor through the center tap of the piezo element, this instantly switches off the transistor and in turn the piezo also switches off, releasing the base of the transistor.

 The transistor reverts to its original state and the cycle repeats, generating oscillations or the required “buzzing” frequency.

The center tap from the piezo transducer plays an important role in sustaining the oscillations and therefore in this particular design we need a three terminal piezo rather than a two terminal one.

The oscillations produced at the collector of the transistor is dumped into the coil, saturating the coil with magnetic inductions. The coil kicks back the stored energy during the oscillations, magnifying the generated AC across it.

This stepped up AC is applied across the anode and the cathode of the piezo element, which starts vibrating sharply according the pitch of the frequency, generating a shrill, ear piercing sound in the air.

However to make the sound audible at maximum intensity, the piezo transducer needs to be stuck or installed in a special way inside its housing.

For this particular application the piezo element needs to be stuck at the base of its housing which must consist of a hole having a diameter of about 7 mm. 

The piezo element cannot be stuck directly over the base of the housing, rather it must stuck and positioned over a soft, pure rubber ring, having diameter 30 % less than that of the piezo transducer.

Only if the above fixing procedure is followed, the buzzer will sound, otherwise the sound may get choked and fail to reproduce.

 Parts List

R1 = 100K,
R2 = 4k7,
T1 = BC547,
L1 = Buzzer inductor,
PZ1 = Piezo element, 27mm, three terminal
Rubber ring = 22mm

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How Do Circuit Breakers Work To Prevent Electrical Fires

The main work of the breakers is to limit the current of the conductor upto a safe level.As we all know that there are always too many appliances plugged in together in one circuit,which occurs a load on the conductor. You trip a breaker, hopefully you then transfer load to another circuit.
 Breakers use two different methods to accomplish tripping, one is a bimetallic strip.The current passes directly through it and when current crosses the highest limit according to the particular designed breaker it causes the strip to deflect. It acts on a mechanism much like the sear in a guns trigger, the deflection pulls the trigger causing a spring to open the contacts and turn off the circuit. Another type is thermal magnetic, current passing through the breaker causes a magnetic field to act on a coil tripping the breaker.

When breakers are wired and work properly they prevent fires.An electrical fire is any fire that is caused by electrical short circuits, overloaded circuits or faulty electrical equipment. Anything that causes excessive current flow has the ability to create fire, including lighting the number one cause of overloaded circuits. Make sure you don’t have an outdated circuit breaker box by finding an electrician to check it for you.
The Things Which You Can Do To Prevent An Electric Fire :
1. First of all keep this in your mind that the main reason of an electric fire is mostly an overloaded electrical circuits,so the first thing you can do is not to put an excessive load on one circuit.
2. Identify the circuits in the breaker box. The breaker box usually tells the amperage of each circuit as well as the outlets serviced by the circuit.
3. Maintain wiring’s, appliances and electrical fixtures.

Another thing to put on your list of things to do as a responsible homeowner is to maintain your appliances and make sure the wiring in your home is updated.
4. Ask an electrician about installing ground-fault circuit interrupters (GFCIs) in your home. GFCIs quickly shut off power when problems occur, minimizing electrical shock hazards.
5. Appliances that malfunction may cause an electrical fire, so make sure your appliances are working properly. If you have an electrical appliance that you know is overheating or short-circuiting, shut off the breaker before you unplug the appliance. Electricity takes all paths to the ground, even if that means through you.

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How to Make a Dual Tone Siren Circuit

This electronic siren gives out a continuously varying high amplitude sound. Since the supply voltage is not critical, it can be used in cars, motor cycles or at home. It can replace the ordinary call bell. - . The circuit consists of two separate free running multivibrator and an oscillator.

A free running or astable multivibrator is one which has two quasi-stable states and the output of one stag is connected to the input of the other through a coupling capacitor.

Since both the states are quasi-stable, the output attained is continuously varying in nature i.e. high, low high low-.

 The output is in the form low pulses, the frequency of which depends on the base biasing resistor and the coupling capacitor, When these resistances and condensers for both the stages are of different values, the output ` wave form is rectangular; this is because the time constant of the two quasi-stable states becomes different.

If this time constant of the two, states is made the same, the output obtained then is square wave. Two states of the multivibrator are made identical by the use of the same values of components.

The components used in the circuit (Fig). result in a square wave output and the time constant selected is so as to give a fairly good rise and fall of the siren.

However, one may change the value of coupling capacitors to get any other desired time constant. The second unit is an oscillator section. The condenser connected at the output is the feed back condenser. It determines the tone of the siren.

Higher the value of the condenser the lower is the pitch. for high pitch sound (generally used in siren) feed-back condenser ranging from 0.047 uf to 0.1 mfd should be selected. The speaker may be metallic case (horn type) or small planer cone. The metallic cone horn gives better results.

Parts for dual tone siren circuit

R1,R2,R5,R6= 22K
R3,R4 = 2K2
R7 = 10 Ohms, 1 watt
C1,C2,C4 = 0.1uF
C3 = 22uF/25V
T1,T2 = BC557
T3 = BC547
T4 = 2N2907 or 8550

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How to Installation A Car Stereo

Car Stereo Installation Guide - Want to save some money? Ever wonder if you could do a car stereo installation yourself? Yes, you can do it yourself! Go ahead, spend that money on your hardware! Don’t spend it on labor. Besides, doing a car stereo installation yourself can be a very rewarding experience, not to mention you can learn a lot from it too. Nothing beats the feeling of seeing your “creation” in action, running smoothly and perfectly.

But be very careful, you really won’t want to damage your expensive hardware. Well, most car audio hardware are no-brainers to install, you’d find that most of the time the parts have specially shaped sockets and slots etc. and would only fit where it’s supposed to be installed. Still, it’s best to proceed methodically.

In a car stereo installation, you have to determine what kind of rig you’re going to put into your vehicle. If you’re a beginner, it’s best you do a car stereo installation if it’s just a simple system. You may want to leave the complicated stuff to the professionals, like installing delicate equipment like LCD panels, motorized parts etc. especially if it requires the creation of custom panels and such. 

Head units are one of the easiest to do in a car stereo installation. Fortunately, most units follow the same size standards (DIN). In many cars, once the factory radio is removed the aftermarket radio will fit in the hole. In many other cars, a kit is needed if the factory hole is too big, or not deep enough. In some cases the dash has to be cut.  Any car stereo store should have kits required for installation. 

There are two types of mounting in a car stereo installation. ISO mounting is when the radio can be screwed to existing factory radio brackets, such as in most Japanese cars. Ring mounting is when an aftermarket radio comes with a metal ring that gets mounted to the factory radio hole or aftermarket kit via bendable tabs. In many cars, dash and trim rings have to be filed to enlarge the radio hole. Once the ring is installed, the radio slides in and is held by snaps. In most cases, special tools are required to remove the radio.

Speakers are very critical in a car stereo installation. No matter how expensive your speakers are, if they are not properly installed, the sound will not be up to par.

In a simple car stereo installation, you’ll probably be using speakers that fit into a factory location. Just make sure there are no gaps or holes. Sometimes building a wood or fiberglass baffle helps reduce holes and gives you much better sound. But always be careful when using power tools around speakers. Car stereo installation warranties usually dont cover holes in speakers.

For unconventional speaker locations, sometimes metal has to be cut. You might want to leave this to the professionals, tools like plasma cutters and pneumatics drills are required. But if you’re going to insist, a pair of metal snips (left and right cut) will do.

A car stereo installation has to put up with vibrations and other noise sources in its environment. Even though it is impossible to eliminate these completely, there are products that will greatly decrease the noise and rattling, particularly on non-luxury cars. Liners, sprays and adhesive strips and even carpeting applied onto the panels can make a world of difference.   

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How to Build a Pyro ignition Circuit Electronic Pyro Igniter system

The
following conversation was made by Mr.Tom and me regarding the circuit
idea of a pyro-iginition system. I was asked to design
the particular circuit idea by Mr.Tom in Fiverr.com.
The discussion explains the details of his requirement and how it was almost fulfilled by me
I was wondering if you could design me a system for a simple pyrotechnic firing system. 
An input trigger would (maybe 5-12v) pulse would switch on que1, another pulse would switch cue2 (binary counter). 

A
total of 16 channels (cues), each cue would be fired with from mosfet
pair. Ideally control circuit would have independent power supply to
power to cues. 

It
would also be nice to have a timer which could on pulse fire each cue
in sequence e.g. cue1 wait 1 second cue 2 wait 1 second cue3 etc. 

Either this of some kind of programmable pic (picaxe etc) so the functionality can be changed. 

Kind regards 
Tom

Hi Tom,
I
can design the control circuit along with the timer, however Im
interested to know what would be connected to the mosfet outputs,
because that looks the difficult part if Im required to set up those.

Thanks
Swagatam

Heres the pyro-ignition control circuit:

Next up is the mosfet output stage:

Hi Swagatam,
I dont seem to be able to get the control circuit to work.
Where does the external trigger connect to, if i connect a ground just before R5 can I use this as the trigger?
Thanks
Tom

Hi Tom,

The circuit starts sequencing the moment power is switched ON, so the "power ON" switch itself acts as the external trigger.

When
power is switched OFF, the circuit resets and comes to its original
state, so that when power is switched ON again, the cycle can repeats.

Thanks,
Swagatam

Hi Swagatam,
Thats not what I asked for.
The external trigger should either start the timing sequence if selected or step through each output on each trigger input.
Referringback to the conversation
"
Function 1
Trigger -> Cue 1 fires (stays on for 100ms to ignite firework)
Trigger -> Cue 2 fires (stays on for 100ms)

Function 2
Trigger -> Fires all Cues in sequence (cue 1,2,3 etc) from a internal modifiable timer

Function 3
The
circuit diagram also has continuity test for each cue, this should be a
low enough current as not to fire igniter this is to be displayed
through an led on each cue.
"

Regards
Tom

Hi Swagatam,
Ive attached a circuit diagram of an open source wireless firing system, the files can be found here
http://code.google.com/p/openpyro/downloads/list.
The system will fire these http://www.category4.co.uk/igniters/technical/igniters.php
If
youre just using a binary counter I think you might need to double the
stages(bits) and pulse the clock after 100ms to turn off the mosfets in
case of short circuit.

If you could replicate attached circuit without the wireless this would be fantastic. Ill pay for extra gigs if needed.
Thanks
Tom

Hi Tom,
From the above description what I understood is that the particular fireworks needs to be ignited in some sequence.

The
fuses would be loaded across the relevant mosfets and the triggering
timing would be such that the mosfets are switched only for some
fraction of a second, just enough to ignite the fireworks and then shut
off.
The sequence will go on repeating until the last mosfet is fired...am I correct?
If
my interpretation is right then I can go ahead with the circuit and
design it using ordinary discrete components, no need of any
microcontrollers.

Thanks,
Swagatam

Yes,
Function 1
Trigger -> Cue 1 fires (stays on for 100ms to ignite firework)
Trigger -> Cue 2 fires (stays on for 100ms)

Function 2
Trigger -> Fires all Cues in sequence (cue 1,2,3 etc) from a internal modifiable timer

Function 3
The
circuit diagram also has continuity test for each cue, this should be a
low enough current as not to fire igniter this is to be displayed
through an led on each cue.

Could this led be also lit when the cue is fired.
Tom

OK, function1 refers to a manual triggering option in the circuit? right?

There should be power to the circuit at all times, when a plus trigger is applied to the system it should step.

Hi Tom,
In our circuit this can be done through a simpler modification, kindly view the attachment.
Pressing S1 initiates the sequencing at any instant and releasing it stops the process.

Thanks
Swagatam.

OK let me try an explain again.
The circuit is a stepper, each trigger pulse it receives progresses the binary counter on one.
So trigger +12 v, binary counter increases one.
Trigger again +12v, binary counter increases one again.
The trigger pulse it totally separate from this circuit and comes from another source.
Easy enough, just a binary counter and outputs.

I
also want another function to allow the first trigger pulse to start a
timer a clock the binary counter on its own. This time is variable. So
there would be a switch to allow you to access this mode. So binary
counter output 1 would feed back into the timer circuit if a switch was
closed.

Hi Tom,
Just have a look at this modification, I hope this one works as intended.
S2 is a SPDT switch, when positioned toward B, it responds to the pressing of S1 and steps with each trigger from S1.
When S2 is moved toward A, pressing S1 does the following things:
T1 and T2 instantly latches powering the timer IC 4060 via T2 and T3.
IC 4060 starts clocking the IC 4017 for the required actions.
Putting
S2 back to point B resets the circuit to its previous mode, that is to
the manual mode. However to reset the IC 4017, it will need to be
switched OFF and then switched ON again.

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