SPY BUG

Mini Audio Transmitter

I'm going to show you how to build your own portable audio transmitter. This transmits FM waves so you could easily get the signals on your mobile phone, radios, etc. As the name and the picture indicates it is very small and is approximately the size of a 9v battery clip.

This transmitter is like the ones in the movies which are used to spy on people or try to record conversations, well don't use this this to spy on anyone, its just for educational purpose only.

What does this do?

• Well all this is a FM transmitter so you could start your own mini FM station.

I'm going to build a mini FM receiver soon, to go with the mini FM transmitter

How does this work?

Well all of us have heard of "frequency modulation", most commonly known as "FM", this circuit works on the very same principal to transmit audio signals captured by the microphone. This circuit uses BC547 transistor to amplify the signal and then frequency modulate it. Since it is tiny and powered with just 9v the signal range is limited to only 15m.

If you like my project you can vote for me in the battery powered contest.

OK now enough of the talking and let's start building.

STEP 1: TOOLS AND COMPONENTS

Like always lets start with getting all the parts, the list is quite simple all you need is

Components

• BC547 Transistor
• An microphone
• A variable capacitor 47pf
• An Inductor (see steps for description)
• 4.7k Resistor
• 330ohm resistor
• 1n capacitor (102)
• 10p capacitor
• 9V battery
• LED(optional)

Tools

• Soldering Iron
• An FM receiver (any mobile phone)

STEP 2: COMPONENTS

I got almost all of the components from a pile of old PCBs I had in an old forgotten box. All I had to get was the BC547 and the electret microphone. Actually I did find the BC547 in an old PCB but i was not sure if it would work. It looked quite burnt to me. The old PCBs had many components resistors, crystals, diodes, etc. I may use them some day and for know back in the box.

I had to de-solder the parts of the old board, for those who don't know how to solder and de-solder there is a bunch of instructables that describe how to do this and learning to solder is not a hard task.

STEP 3: PCB

First of all lets start with cutting up a PCB to the required size. The size to compare is a 9v battery clip, it might look quite small in the beginning but don't worry it would hold all the components just fine. Use a sand paper for smoothing the sides of the PCB and to clear out any rough edges.

Make sure to get a PCB with big holes as the variable capacitor pins won't go in the standard size holes.

STEP 4: MICROPHONE

You can get the microphone at a local hardware store. And be sure to get some male pins to hold the microphone in place refer the picture as to how to solder the microphone in place.

Why not use some wires to hold the microphone?

I would not suggest wires as when you tape the circuit if the last few steps you would not get a clear audio. I tried it and got a lot of noise. I got lesser noise when I used the male pins soldered to the microphone.

STEP 5: CIRCUIT

Once you're done with the PCB and know where and how to solder the microphone now it's time to complete the rest of the circuit. Follow the circuit above and solder all of the components. Make sure not to leave any space between any of the components if you need to get the circuit small. For the inductor use 0.5mm wire and 8 turns, with each turn with a diameter of 6mm.

And for the antenna just use a thin 5cm long wire. For more stability you could center tap the coil and solder the antenna to the center tap.

Also If you notice the circuit has a LED in it, it is used to show when the circuit is functional. I did not add the LED in my circuit because it was draining my battery faster.

STEP 6: TAPING TIME

Once you got the circuit like the one in the above picture, it's time to cover it with tape. I used wiring tape to cover the whole circuit except the microphone and the variable capacitor. This is an important step as when you proceed to the next step, where you tune to the required bandwidth. Touching the circuit (mainly the coil) with your fingers would lead to severe noise.

You could also use a heat sink instead of tape, I used tape because I wanted to experiment withe circuit so I did not want it to be permanent.

STEP 7: TUNING TO THE REQUIRED BANDWIDTH

Now it's time to tune the circuit to a required bandwidth, you could do this in two ways.

1. Use your mobile phone to find the signal
2. Manually tune the variable capacitor to match a frequency

The first step is recommended all you have to do is power the circuit and turn on auto find bands on your mobile. Your mobile would scan for channels and all you have to do is look for your transmitter (play some music in front of the transmitter) on that list.

The second method is time consuming, in this method you have to turn on your radio and the circuit. Keep the radio at a specific channel, and then tune the variable capacitor extremely slowly. When you hear stuff on the radio maybe a song that you are playing stop and the bandwidth on the radio is the required bandwidth.

STEP 8: RE-CHARGEABLE VERSION

After using the 9v battery circuit for some time I thought of replacing the battery with rechargeable Li-ion batteries. If you have viewed my previous instructables you would have seen that I use these batteries a lot.

The rechargeable batteries provide longer transmission than the common 9v battery.

POWER GENERATING SHOE

INTRO:

The project is be accomplished by using piezoelectric materials. Piezoelectricity, also called the piezoelectric effect, is the ability of certain materials to generate an alternating current voltage when actuated.Certain ceramics, Rochelle salts, and various other solids exhibit this effect. For example, (Pb[ZrxTi1−x]O3 where,0≤x≤1), also called PZT, will generate measurable electricity when their structure is deformed by about 0.1% of the original dimension(International AAAI Conference on Social Media and Weblogs, 2012). In this project, the generated electricity on a specific time will be recorded and determine if it would be enough to completely charge a Li-ion battery or a high capacity capacitor.

The project is be accomplished by using piezoelectric materials. Piezoelectricity, also called the piezoelectric effect, is the ability of certain materials to generate an alternating current voltage when actuated.Certain ceramics, Rochelle salts, and various other solids exhibit this effect. For example, (Pb[ZrxTi1−x]O3 where,0≤x≤1), also called PZT, will generate measurable electricity when their structure is deformed by about 0.1% of the original dimension(International AAAI Conference on Social Media and Weblogs, 2012). In this project, the generated electricity on a specific time will be recorded and determine if it would be enough to completely charge a Li-ion battery or a high capacity capacitor.

The piezoelectric effect, by which a material generates an electric potential in response to a temperature change, was studied by Carl Linnaeus and Franz Aepinus in the mid-18th century. Drawing on this knowledge, both René Just Haüy and Antoine César Becquerel posited a relationship between mechanical stress and electric charge; however, experiments by both proved inconclusive. The first demonstration of the direct piezoelectric effect was in 1880 by the brothers Pierre Curie and Jacques Curie. They combined their knowledge of pyroelectricity with their understanding of the underlying crystal structures that gave rise to pyroelectricity to predict crystal behavior, and demonstrated the effect using crystals of tourmaline, quartz,topaz, cane sugar, and Rochelle salt (sodium potassium tartrate tetrahydrate). Quartz and Rochelle salt exhibited the most piezoelectricity.

A piezoelectric disk generates a voltage when deformed (change in shape is greatly exaggerated) The Curies, however, did not predict the converse piezoelectric effect. The converse effect was mathematically deduced from fundamental thermodynamic principles by Gabriel Lippmann in 1881. The Curies immediately confirmed the existence of the converse effect, and went on to obtain quantitative proof of the complete reversibility of electro-elasto-mechanical deformations in piezoelectric crystals. For the next few decades, piezoelectricity remained something of a laboratory curiosity. More work was done to explore and define the crystal structures that exhibited piezoelectricity. This culminated in 1910 with the publication of Woldemar Voigt's Lehrbuch der Kristallphysik (Textbook on Crystal Physics), which described the 20 natural crystal classes capable of piezoelectricity, and rigorously defined the piezoelectric constants using tensor analysis.

Step 1: Parts And Materials

Parts/ Materials:
- Cheap/ Generic USB Powerbank
- Piezoelectric Transducers (6x)
- 1N4007 Rectifier Diodes (4x)
- Hookup Wire (at least 12")
- Old Pair Of Shoes
- Contact Adhesive

Tools & Equipment:
- Digital Multimeter
- Multitool (w/ pliers)
- Rotary Tool
______________________________________________________
Optional: 
- 100nF Mylar Capacitor (for testing)
- Hoop & Loop Fastener (Velcro)
- LED Indicators (for testing)
- Superglue (for fixing wires)
- Smartphone Sport Strap
- 5v Switching Regulator (w/ supercap)

Alternatives: (since not all can afford them)
- PowerBank > Old phone batteries + Recycled 5v Inverter
- Peizo Transducers > A pair of old & outdated earpiece
- Rotary tool > Hot Nail (for melting plastic)
- Multitool > A pair of pliers will do

Step 2: Measuring Your Sole

Get the size and shape of your shoe's insole then get a pair of heavy-duty shears/ snips and carefully cut the PVC material. The plate will act as the primary mount of the piezoelectric discs/ elements.

Remember: Thickness matter, you need at least 2-5mm. If your material is too thick, the piezo elements will break due to too much flexing. If your material is too thin, the piezo element won't bend at all thus converting less power.

Step 3: Find And Cut An Ideal Material (Sheet/ Plate)

Now surround the PVC plate with three piezo discs. How do I know where the center is? The "center" that I'm referring to is area where all the pressure is withdrawn by your foot, your sole.

After getting a fix preview of the setup, get a pencil and trace the piezo discs. Finally use your compass to draw smaller circles, about 2mm smaller in radius. The 2mm spacing will act as your margin.

What material should I use?
Based on my design, I needed a plate that is 2-5mm thick, lightweight, stiff and can endure a lot of flexing. Metals are too stiff while carbon fiber is too thin. After playing around with a bunch of materials, I've found out that PVC fits best in my application.

Were did you get the PVC material? 
PVC materials are all around us. You can find them in your local hardware store but in the form of pipes. I got mine from our excess supply of PVC pipes when our house was built. Recycling means free $$$ for me! :)

Step 4: Grinding Holes On PVC Pads

In this step, grinding is required to bore/ drill round holes. Since I don't have large drill bits (as large as the marked area), I've thought of way to cleanly cut the holes and that's by using my handy rotary tool. 

If you don't have a rotary tool, you can still cleanly cut the plastic by doing it "the old fashioned way", by heating an iron nail and melting the plastic.

Step 5: Gluing The Piezoelectric Elements

These piezo discs must endure a lot of flexing since you'll be stepping on them repeatedly! Never use superglue, if you do, the moment you step on your insole the piezo discs will snap off the PVC pad. Instead, use those quick setting "contact adhesives". Their rubbery characteristic makes them ideal for this project since they stretch whenever they are bent.

Step 6: Soldering The Piezos Together

Solder all piezo elements together in parallel. Don't solder them in series because you'll need more current than voltage and those piezoelectric discs will cancel each other's power output when not actuated at the same time. 


Piezo elements produce AC currents. Unlike DC currents, you can't just tap in the line. since AC currents are always alternating polarities. Just like power generators, whether it may be solar or petrol, you can't just tap directly to the powerlines without aligning the AC wave's phase otherwise the generator will cancel each other. (Ex. Negative meets Positive - Positive meets Negative). This infers that parallel works best for our project. 

Improvements:
Through this process of experimentation, I've realized that even if they are hooked in parallel the piezoelectric elements can still cancel each other's output off (when not actuated simultaneously). This leads to conclusion that you'll need to add one bridge diode per piezo element/ disc.

Step 7: Building A Bridge Diode

Peizoelectric elements produce AC when subjected to mechanical stress. Unfortunately, USB devices need DC and not-AC. A bridge diode is required to filter and convert AC to DC. 

Schematic:
Just follow the schematic diagram above. Solder the peizo discs to your bridge diode. Remember AC has no polarity, you can invert the wires either way. The load (shown as a resistor) represents your appliance.

Recycling: 
CFL bulbs contain electronic ballasts, each ballast contains at least six to eight rectifier diodes. Those diodes are compatible with our project. Please be careful in disassembling CFL bulbs, I'm not liable if any of you get injured.

Step 8: Adding Foams Pushers

Now glue small a small piece of foam on the very center of each piezo disc. These foams will act as pushers. These foams will squeeze the piezo discs inwards (like sandwitches) while walking.

Step 9: Observation And Testing

Finally, we are going to test the validity of or theory. Start by getting a digital-tester and switch it to the 2 digit DC range. Remember, piezo elements produce a short burst of current the moment you push them so adding a 100nF capacitor should make the readings much more readable.

My volt meter displayed:
Pressing By Hand = 15.03 volts (2mA)
Walking By Foot = 18.53 volts (5mA)
Running By Foot = 27.89 volts (11mA)

Step 10: Installing The Insole

Slip the insole generator between the shoe and the insole.

Step 11: Adding A Powerbank + Soldering

The insole generator peaks a voltage of 28 volts, the current may be small but the voltage is enough to damage the powebank's 5v charger (circuitry). I won't be using the 7805 since it's quite old and inefficient. Right now, my insole generator is soldered directly to my powerbank's lithium battery. It works but it's not completely not safe.

UPDATE: Say goodbye to the huge bulging powerbanks! I have a newer version of the project, the powerbank is now integrated with the insole. I also added a charge collector circuit.

SOLAR POWERED USB CHARGER IN A CUP!

Mr. Buzz is a solar powered USB charger in a cup! The lightweight and flexible PowerFilm solar panel charges up the 2400mA battery pack so you can recharge your USB device even without the sun. 

What's so cool about Mr. Buzz?

• Uses flexible solar panels that are extremely light, unbreakable and can be mounted on nearly anything.
• Rechargeable batteries in the cup let you charge / power your device even if the sun isn't out.
• Total power storage of around 2,500 mA, more than enough for a full iPhone recharge, or multiple recharges for smaller devices, like a shuffle. 
• Has a USB 'Type A' jack, the same jack that's on your computer, so you can connect to any USB device.

Mr. Buzz is available as a kit from Gadget Gangster.

Step 1: FAQ

What is Mr. Buzz?
Mr. Buzz is a solar powered USB charger. A flexible solar panel (PowerFilm) is used to charge Nimh batteries, so Mr. Buzz can charge up your USB device even if there isn't any sun.

What can I charge with it?
Mr. Buzz uses a 'Type A' USB Jack, the same style USB jack that's on your computer, so it will physically connect to nearly any USB device. That said, some devices don't like being charged by a battery pack or solar panel.

Usually, if you plug your device into your computer and it needs to install software before it begins charging, it will not work. Here's what I've tested:

WORKS:
Apple iPod: Mini, Nano, Shuffle 1G/2G, Classic, Touch, iPhone
Creative Zen Micro
Nintendo DS (with an adapter cable)
Microsoft Zune
ATT Fuze, aka Touch Pro
Motorola S9-HD
PS3 Bluetooth Headset (in holder)
Verizon PPC 6700 (HTC Apache)
Creative Vado
Creative Zen Stone

DOESN'T WORK:
So far, any device that doesn't work with my usb wall charger will also not work with Mr. Buzz.  I've tried;
PS3 Wireless Controller
Xbox 360 Wireless Controller

How long to does it take to recharge?
It should take the same amount of time as if it were plugged into a wall charger or any other device. To charge my phone from dead to 75% takes 90 minutes (same as a wall charger).

How much juice does it have?
Total power storage is about 2,500 milliamps. This is enough to charge my phone (which has a 1,300 mA battery) about 2 full times. An iPhone's battery is 1,200 mA, so you should about 2 charges, too. Smaller devices (like a shuffle) will recharge many, many times.

What batteries should I use?
You should only use rechargeable AA batteries (Nickel-Metal Hydride).  With 4 batteries, Mr. Buzz provides 4.8v-5.2v.

Do I have to use batteries?
Yes - the solar panel slowly trickle-charges your batteries, and they aren't large enough to directly power your USB device.


Mr. Buzz was designed by James Long at Lil' Brother SMT Assembly.  A kit or bare PCB are available at Gadget Gangster.

Step 2: Preparation: Tools

This is a great project to learn how to solder. It only takes about 15 minutes to put together, too. There are a ton of great instructables on how to solder (one here).

Tools
You'll need a few tools to assemble the project;

1 - Soldering Iron and solder. Leaded solder is easier to work with, and a 15-40 watt iron is just fine. A conical or chisel tip works well.

2 - Dikes. Diagonal cutters are used to trim the excess leads from components after soldering them down.  

3 - Batteries. Mr. Buzz needs 4xAA rechargeable NiMh batteries.

Step 3: Preparation: Parts List

Here are the parts you'll need to put Mr. Buzz together. If you've ordered the kit from Gadget Gangster, double check to make sure your kit has all the parts listed. If there's anything missing, just email us at info@gadgetgangster.com;

Eagle 4xAA Battery Box
Mouser Part #12BH348/C-GR
Qty: 1

Mr. Buzz Circuit Board
Source: Gadget Gangster

.1uF Ceramic Capacitor
Qty: 2

100k ohm 1/4W Resistor (Brown - Black - Yellow)
Qty: 2

USB Type A Jack
Mouser Part#649-87520-0010BLF
Qty: 1

About 1 Foot of Hookup Wire

3V PowerFilm Solar PanelsSource: PowerFilm
Qty: 2

Not included in the kit are 4xAA rechargeable batteries, which you'll need to provide.  

Step 4: Make It: Step I

Ready to begin? Building Mr. Buzz is easy. Let's start with the resistors.

Take the 2 resistors (100k ohm, marked Brown - Black - Yellow), bend the leads at a 90 degree angle and insert them into R1 and R2.

Flip over the pcb, solder down the parts and trim off the excess leads.

Step 5: Make It: Step II

Take the two Ceramic capacitors and insert them into C1 and C2. These caps aren't polarized, so it doesn't matter which direction they go in the pcb.

Flip over the board, solder them down and trim off the excess leads. Save one of the excess leads for the next step.

Step 6: Make It: Step III

With the bit of excess lead you saved from the last step, you're going to bridge a connection on the board.

Bend the wire in a 'U' shape, and insert one end in the hole marked 'NoREG', the other end goes in the middle hole.

Why is this jumper here? If you want to use Mr. Buzz with a bigger solar panel or another power source, you can do so with this circuit board! You just jump the middle hole to 'Reg' and jump the two holes in the 'REG Enable' box. You would then add a voltage regulator at U1.

You'll want to use a 5V regulator.  NOTE: The pinouts for the regulator aren't compatible with the 78xx regulators, you'll want to use something like this, instead.

Step 7: Make It: Step IV

We're almost done with the board - we just need to add the USB jack. Take a look at the photo. Drop the USB jack in the board, flip it over and solder it down.

Step 8: Make It: Step V

Add the battery box as indicated in the photo. The red wire goes in the hole marked '+' and the black wire goes in the hole marked '-'.

Step 9: Make It: Step VI

Now, let's work on the panel.

First: Set the 2 panels on the table, exactly as shown. Note that each panel is polarized, the pattern on the panel (the repeating 'T' pattern) shows you the correct polarity.

Take a bit of hookup wire (or some of the extra leads you've trimmed off) and set it on the panels, as shown on the photo. This wire is going to be used to connect the panels in series.

With your soldering iron in one hand and some solder in the other, solder the extra wire straight to the copper 'braid' on the panel. There's a very thin film over the copper braid - don't worry about it, your solder will melt right through it and adhere to the copper braid. Once you've got it affixed to the first panel, connect the other end to the other panel, as shown in the photo.

Take the remaining hookup wire and cut it in half (2x 6 inch lengths). You'll use this wire to connect the panel to the Mr. Buzz circuit board.

Step 10: Make It: Step VII

Finally, connect the panel to the circuit board. Note on the photo how the panel connects.

That's it - You're all done!

Usage and Mounting
I suggest you join the 2 panels with a bit of scotch tape - it will make them more rigid. To mount it, you can tape it directly to a surface, use double-stick tape, or just let it hang freely. PowerFilm is very durable and flexible - I wouldn't fold it or crush it, but it will curve around a soda can, coffee cup, or on a backpack.

To use Mr. Buzz, just add your rechargeable batteries and flip the 'on' switch on the battery back and plug your device in. Charging should start immediately. Also, if you're not charging Mr. Buzz's batteries or charging your USB device, you should flip the battery switch to 'off'. If you don't, the batteries will slowly lose their charge.