The telegraph was an early form of electrical communication designed to help people get messages across distances. The distance the telegraph would work was limited since it used DC power which is subject to voltage loss when used with long lengths of wire. To compensate for this problem telegraphs would rely on the message being relayed from one area to another. Basically the message would be sent from the first point to the receiving point at the next station and then with the signal in a weakened state the message would have to be repeated and transmitted to the next station over and over again until it reached it's destination. The circuit below is an easy to make modern version of the telegraph.
    Please buy the parts suggested or similar parts and make the circuit as illustrated. Pay close attention to the color of the wires or it will not work. Also use care to not get poked on the wires and to be neat with the connections. Leave no frayed wires and twist the wires together well. Also tape each connection with electrical tape when done.  The wire between your telegraph stations can be long enough to go between several rooms. When your momentary push buttons are pushed the piezo tone source at the other station will sound. You can make up your own code or learn Morris code to communicate. Please remember to not put your ear next to the piezo tone source as the sound pressure is high coming from such devices. 

Safety Basics

    Although the parts needed for this project are similar to parts you would find in kits from numerous kit suppliers we wish to underline the safety requirements when working with electrical devices. It is expected that any experiments done will be under adult supervision and kept out of reach of small children.
   Electricity can produce painful, injurious or even deadly shock by overloading your nervous system. Do not use power from wall sockets or other high voltage sources.  You must receive extensive professional training prior to such work. The power coursing through one 100 watt light bulb is enough to cause certain death for at least ten people simultaneously. Use low power sources such as battery power from regular batteries for experiments and remember to never leave an activated experiment unattended as even low voltage circuits have been know to cause fire hazards. Keep experiments away from any source of combustible ignition. If an experiment deals with motors, gears or propellers use caution to not be pinched or struck by your device. As a point of safety practice use the “One Hand Rule” (described below). Never open potential sources of chemically stored high voltage such as camera flashes or televisions. Always wash yours hands well before eating after working on electrical or electronic devices to avoid the risk of lead exposure which can have injurious effects to the brain and nervous system. Keep your experiment out of the reach of children and seek adult guidance when performing an experiment. Never overload or reverse polarity of a part with out the approval of a knowledgeable adult or burns and chemical spills can occur. Do not use high power batteries such as car batteries or gel cell without fusing, special guidance and assistance from a qualified adult.

One Hand Rule = When working on an electrical device that is active always put one hand in your pocket while adjusting your device to avoid having electricity going through one arm, across your chest and down the other arm to a grounded material which would complete a circuit by way of your heart. Although you are working with low voltage use this opportunity to get used to this habit.

Wash Hands Well = After you complete your work always wash to avoid exposure to lead and chemicals.

Soldier = Always use silver/tin electronic soldier when soldiering is needed, and tape your connections when through. But remember that the parts that come from the factory already have their leads coated with a lead tin soldier. Use proper care to get cross ventilation that vents to the outdoors and be vary careful of the heat the soldiering iron produces. Note soldiering should only be done by a person of a suitable age or under adult supervision. Do not work with soldier or electronic parts in a kitchen or similar area. Use a workshop, garage or other suitable area.

The understanding of electricity begins with an understanding of the Atom. As you have probably learned in school atoms are made of Protons, Neutrons and Electrons.  In electricity we focus first on the Electron as it is negatively charged and venerable to outside stimulus. Materials that conduct electricity have what is refereed to as Free Electrons which are Electrons that easily jump to adjoining Atoms. These Free Electrons jump from one atom to another down wires or other conductive paths. It may help to picture this as a bunch of marbles in a tube with the one on the end hitting the other ones until at the other end the last one zooms out. With electricity this happens at astonishing speed. If we were able to view the travel of a single electron down a wire it would seem to take longer than the speed at which the electrons take for their individual jumps due to the fact that their travel pattern varies as they are buffeted along floating in and out of one atom's orbit after another. An interesting and useful attribute of electricity is the fact that wherever electricity is magnetism also exists. Every electrically charged wire creates magnetism.  If you reverse this principle the reality still holds true. Wires that are exposed to magnetism product electricity. This is how generators work.

Current or amperage = Mathematical symbol (I) Current is the mass of electrons traveling down a wire at a given instant. Low current can be compared to a football player pushing against another player to complete the run across the field. High current would be a group of players pushing at the same time. The more players (electrons) the more current.

Voltage = Mathematical symbol (E) Voltage is the pressure that the electrons are traveling with down a wire at a given instant. If we use the football comparison above think of voltage as how hard the player or players push. The more they push the higher the voltage.

Watts = Mathematical symbol (P) Watts refers to the power output measured as voltage multiplied by amperage and is noted as I x E = P. This is a basic algebra that gives us the power consumption of a circuit.

Resistance = Mathematical symbol (Ω) Greek Omega. This is the Common unit of measuring resistance called OHM. Resistance is the resistance a conductor has to the flow of electrons.

Ohms Law =  George Ohm invented a vital and simple math to explain the relationship between resistance, current and voltage it is expressed as E = I x R
 

Watt = Mr. Watt invented a vital and simple math to explain the relationship between current, voltage and power   P =  I x E

Ohms Law + Watts Law ??  = Together Ohm’s Law And Watts Law can be used to figure out the safe operation of a circuit and how to operate it efficiently. Their contribution brought safety and predictability to electrical science. Every electrical device we use has been created with variations on their simple formulas as a  fundamental.

In Electronics & Electrical Science You Will Find That Energy Can Induce Other Energy Forms.  Most energy forms can induce other forms of energy.   Most of these examples are found in everyday devices in our homes!!

(1) magnetic + motion (from wind, water flow, steam etc.) induces electric which induces electrochemical
(2) electrochemical induces electric which induces light
(3) light induces electric
(4) heat induces electric which induces motion  which induces sound
(5) electric induces electromagnetic  which induces kinetic
(6) chemical induces electric which induces electromagnetic which induces kinetic
(7) sound induces motion which induces electric which induces light