Phone Line In Use Indicator

Introduction

The function of this fun electronic project design is to indicate whether a phone line that is connected to many phone extension is in use or otherwise. It is an interesting project for beginners to electronics hobby as there are only a few commonly available parts that are used in this circuit.

Circuit Description

The main part of this project is the use of an N channel power MOSFET IRF511 that has a current rating of 5.0 A at room temperature and drain to source voltage of 60V. If the phone is offhook, it will have a tip to ring voltage of 48V DC. When this voltage is applied to the gate of Q1, it will turn Q1 ON which in turn will bias the Q2 transistor to turn OFF. When Q2 is OFF, LED will also be OFF which means that the phone line is not in use.

When the phone hook is remove, the voltage will drop and cause Q1 to turn OFF. When Q1 is OFF, the gate of Q2 will be biased ON and thus transistor Q2 will turn ON. When Q2 turn ON, LED will also turn ON indicating that the phone line is in use.

Phone Circuit Parts List

Source : Extracted from Popular Electronics Feb 1993, By Charles D. Rakes

ref: electronics-project-design.com/fun-electronic-project.html

Air Flow Detector

This simple circuit uses an incandescent lamp to detect airflow. With the filament exposed to air, a constant current source is used to slightly heat the filament. As it is heated, the resistance increases. As air flows over the filament it cools down, thus lowering it's resistance. A comparator is used to detect this difference and light an LED. With a few changes, the circuit can be connected to a meter or ADC to provide an estimation on the amount of air flow. 

R1           1              100 Ohm 1/4W Resistor               

R2           1              470 Ohm 1/4W Resistor               

R3           1              10k 1/4W Resistor          

R4           1              100K 1/4W Resistor       

R5           1              1K 1/4W Resistor            

C1           1              47uF Electrolytic Capacitor         

U1          1              78L05 Voltage Regulator              

U2          1              LM339 Op Amp

L1            1              #47 Incandescent lamp with glass removed (See "Notes")         

D1           1              LED        

MISC     1              Board, Wire, Sockets for ICs, etc.             

The glass will have to be removed from L1 without breaking the filament. Wrap the glass in masking tape and it in a vise. Slowly crank down until the glass breaks, then remove the bulb and carefully peel back the tape. If the filament has broken, you will need another lamp.

ref: aaroncake.net/Circuits/airflow.asp

Simplest shocker

This is the simpleest way to get harmles high volteges of an batery!

The transformer can be any mains transfomer(110-220V to 1-24V)

Whith the right transfomer it is posible to generate up to 2000V!!! (Don't wory its not dengerus becose of to low curents!)

these transformers normaly have 20-40:1 ratio so how can it make 2000V(200:1 ratio reqierd)?
Its becose some transformers have an good magnetic field breakdown efect(energy is storen in an magnetic field an then relesed as an high voletge spike)

If the releys coil resistanse is too big (inted in the reley the curent goes in the transfomer) the transistor must be hoked up in serial whith the reley coil (this will give lower performace)

I think this thing cod be hoked up whith an TV Flayback transformer too(to generate up to 20 000V)

A big cap (1000uF) parallel whith your power surce can inprove performance(its recomended if an lower curent power suply is used) 

ref: electro-tech-online.com/electronic-projects/12681-project-simplest-shocker.html

Hacked LED Mouse Light

Written by: Alan Parekh

Most of us have a bunch of these old mice laying around collecting dust. If you didn’t make some cool art with your mice last week here is another idea to recycle it into a cool project. This article will show you how to turn an ordinary mouse into a flashlight, perfect for looking into computer cases that always seem to be in the darkest corner of the room.

You will only need a few items for this hack.
* 360 Ohm resistor
* 9 Volt Battery Snap
* Heat Shrink (optional)
* White LED

This is the basic single LED version. A more elaborate version will be documented in the near future. Look at the bottom of this article for a sneak peak of the high end version. 

Look to see how to crack the mouse open. Most have some visible screws on the bottom. This one doesn’t…

After removing the glider pads the single screw is revealed. Removing this screw is all it takes to open the case.

This is a typical mouse. Lots of room and a big roller ball in the middle.

Start carefully removing the guts. Most of the components in this one were just slotted into place.

To make room for this mod the circuit board will be cut. This is also a convenient way to disconnect the switch that we will be using from the original circuit.

As you can see with the modified board installed there is now lots of room to play with.

A plastic fin on the top cover had to be trimmed to allow the battery to be installed. A simple snip of the side cutters is all it took.

There was also a small clearance issue with the side of the battery, we need this extra room since there will be a battery snap attached to the battery. Again the side cutters made easy work of the plastic fin.

I decided to use the original wire grommet as the LED hole. The wire diameter is smaller than the 5mm white LED that will be installed.

The drill press is overkill to enlarge the hole but it was handy.

The base of most LEDs have a flange, to accommodate this I simply used the tip of a soldering iron to melt away a some of the back of the grommet.

This mouse is designed quite well, the grommet slides right back into place with ease.

The LED is now slid into the grommet. Use a bit of hot glue if it is a loose fit, in this case it is held in there quite well with no glue.

Next we will solder some current limiting and one battery snap lead to the mouse switch. I am using the left click switch in this case. It is usually very easy to tell where to solder to since most mouse circuits use only N/O (normally open) switches which is what we need. If the switch has three connection you are usually safe to use the same ones that the original mouse circuit used.

Next I used some heat shrink to cover the resistor and bare wires.

Some wires are now connected to the LED and heat shrink is used to cover the bare wires. Red from the battery snap and the wire from the switch are used.

That is the entire circuit done. You can connect the battery now and give is a test.

Another shot from the side.

Slide the board back into place. Depending on the model of mouse you may need a bit of hot glue to hold it in place. For this one that was not required.

It is possible to have both switches control the single light, all you need to do is jumper the two switches together.

Since we are going to keep the roller ball in place make sure it will not rub on the wires when the unit is closed up.

Connect the battery. In this case it fit quite well, if the case is a bit larger you might need some foam to keep it from bouncing around inside.

Close the lid making sure not to pinch any wires.

That’s it, you now have a new flashlight.

Looks a bit like one of the old optical cordless mice from the front. In fact when it was sitting on the desk I have grabbed it a few times and wondered why the mouse cursor wasn’t moving on the screen…

Give it a push and make sure it works.

Now when you are working on your computer you can use a light that is cool and functional.

---

Here is a sneak peak of the next version of the LED mouse.

This is a three button mouse that controls four white LEDs and four UV LEDs. The UV LEDs are on the bottom and are used to check for counterfit money, cheques etc.

ref: hackedgadgets.com/2006/06/15/hacked-led-mouse-light

TV Remote Control Jammer

Do you have an incessant channel hopper that is driving you crazy? Or perhaps you simply want to enforce your own selections. The TV Remote Control Jammer will do the trick.

This circuit is a redo of an older design which is not effective on modern remotes. Modern remote controls are hard to jam but with a little care this circuit will do the job. The circuit is just a flasher operating at 40 kHz which is the carrier frequency used by common remote controls. The strong 40 kHz infrared flashing interferes with the signal from the remote.

The 50k potentiometer is adjusted to achieve a 40 kHz flash rate (around 20 kohms) and this adjustment is fairly critical. When it is set properly and the LEDs are pointed directly at the receiver's photodiode, the remote control will stop working. The LEDs are operating at about 30 mA when on but the duty cycle is low and the circuit only draws about 7 mA.

Trouble may be encountered if the frequency is set wrong, the LEDs are not pointed correctly, or if the remote is a real brute. More light may be had by adding another resistor and diode string from the collector to the switch but the most likely problem is the frequency adjustment. Use a 10-turn pot and adjust it slowly while changing channels. Or use a frequency counter or oscilloscope to set the frequency, if possible. Make sure that the current drain is about 7 mA - if not, check the polarity of the diodes. A photodiode infrared recaeiver is handy for checking the light output and comparing it to the remote's.

ref: techlib.com/electronics/gags.html

Magic Lamp

No, its not Aladdin's lamp with a genie inside. This magic lamp appears to be an ordinary frosted light bulb with a rather unusual characteristic. Whenever your finger is touched across the base threads and center contact the lamp magically lights! Without wires! It is a most effective illusion if you don't make a big production, "Hey! Check out this magic lamp!", but instead casually remove the bulb from a package of new bulbs and pretend to not notice when it lights. When your victim gasps and grabs the bulb for further investigation just explain away the flash as some sort of static electricity effect and act indifferent.

Construction will probably involve several attempts unless you are familiar with glass working. Collect several old burned-out light bulbs and learn to remove the base without breaking the glass. The bases are glued on fairly well but with gentle prying and twisting they will break loose.

CAUTION: The broken glass is quite sharp and can easily cause a serious cut.

Try not to scar the metal base too much if you want to reinstall it or alternately just peel it off and get a pristine base by breaking away the glass on another bulb. Now the really tricky part is to break off the bottom of the bulb without shattering the whole thing. A glass cutter may be used to score a ring around the base to encourage the desired break. This break should be near the bottom so that when the bulb is remounted on the base the break will not show. Keep your fingers out of the inside of the bulb so that the frosting doesn't get a greasy fingerprint.

Several factors should be considered when selecting a battery and lamp combination. First, the weight should be kept low if the victim will hold the bulb. Second, the lamp should be as bright as practical and should emit light in an omnidirectional pattern. Try those "super Krypton" flashlight replacement bulbs and two AAA cells or one AA cell. A simple version may be constructed by connecting the battery, bulb and base in series such that the circuit is completed when a penny is connected across the base. The more sophisticated version shown in the diagram will respond to the resistance of moist skin and therefore requires less manual dexterity. Mount the circuitry as deep in the base as possible so that it doesn't show through the glass and mount the battery vertically out of the base by securing it with a good quality epoxy. Paint the battery, wires, and components white so they don't show then fasten the bulb back into position with hot-melt glue. Hot-melt glue will allow easy disassembly when the battery needs changing.

ref: techlib.com/electronics/gags.html