[Dwayne]

I was just wondering. . . .

I would be willing to teach a little Radio theory (Practical) on receivers and transmitters if a few of you would like to learn.

It would be the very basic. . enough to where you could actually build your own transmitter and receiver in the simplest form. Enough to where you could trouble shoot the older radio's and have a chance of fixing them, if you had the schematic of them.

That is all up to you. I could also upload schematics that would be easily built, and could be very practical to use in some degrees. . .

Just some idea's to play around with. . .

[budroe]

Appreciate the offer Dwayne. I'm sure there are folks here that would appreciate any pointers and assistance you can provide.

[JJFlash]

I"m in. This is good stuff.

[Dwayne]

OK,

I will start off with the very basics. . .if anyone has any questions, I will answer them. I will also ignore some of the radio theory and electronics theory of components like speakers, detectors, and other stuff, unless someone asks about them.

If I think the question is beyond the scope at this time, I will say so, and answer the question later on.

One thing to remember. . NO QUESTION is a dumb question.

First off. . .we must understand that in order to "receive" a signal, you do NOT need an oscillator or a amplifier to do so. But in doing so, you are very limited to what you can hear. The best example are Crystal Radio's.

They have a coil, a capacitor (hidden usually), a detector, and ear phones. They are very poor radio's. They are very poor for rejecting nearby radio stations. They are only good for strong signals. . . but they are receivers.

Radio waves are A/C. Alternating Current. That means they have part of the wave as a positive component and part of the wave as a negative component. We sometimes measure this as Peak to Peak.

In the Attached Picture, you can see a +5, a 0, and a -5. on the bottom diagram.

This means the signal (or wave) has a Peak to Peak of 5 volts. It shows the positive and negative elements of the wave.

The frequency of the wave, is the number of times it takes to do one full cycle in a second. (From one top of the wave to another top of the wave).

If (in one second) that wave passes by you 3 complete times, that frequency is 3 hz. (Hertz). If it passes by you 60 times, it is 60 hz. If it passes by you 148 million times, it is 148 mhz. Thus, your household current is a radio wave! It is a 60 hz radio wave. It is very slow, but it is still a radio wave.

Now that we know a little bit about waves. . .We need to know what do with them.

[Dwayne]

Radio Waves are picky. . . They are like us. They like certain atmospheres to travel in, and when it is right, it travels quite freely.

Humans like weather about 70 degrees. We can run around, jump, play, make fools of ourselves, and continue until we drop dead because of lack of energy. As the temperature gets higher or lower, us humans start to slow down and hybernate. Radio waves are the same way.

In comes a tuned circuit.

A tuned circuit is nothing but a capacitor and a inductor in series or parallel (mostly in Parallel).

A Capacitor Looks like this: -||-

A capacitor does not allow DC voltage to pass through. What happens, is the DC voltage charges one side of the capacitor and "stops".

A Capacitor allows A/C to go through because as the A/C swings towards the positive, it charges one side of the capacitor, and when it switches and goes towards the negative voltage, the capacitor discharges and charges the other side of the capacitor. . . cycling back and forth.

This means the bigger the capacitor, the easier the A/C or wave can pass through.

An Inductor. . . .

It is nothing but a coil of wire. That coil of wire can have a center piece of metal (to make it stronger or higher inductance) or it can be just "air" to make it a weaker inductor. (Most have some kind of metal center).

Any time a wave goes through a wire, it creates a magnetic field. If you take the wire and make it into a coil, the magnetic field becomes stronger. If you put metal core inside that coil, it becomes stronger yet.

DC will pass through quite happily. But A/C will fight. The reason why? When A/C goes towards the positive voltage, it creates this powerful magnetic field. When it drops and goes towards the negative voltage, It tries to make *another* magnetic field with the negative voltage. AS the Positive magnetic field is collapsing, the Negative field is expanding. . .they oppose each other, they get in a fight and something has got to give, or energy is wasted.

In comes a capacitor and an inductor.

What happens, is. . .if the capacitor is to small, the energy will go through the coils. if it is too big, the energy will go through the capacitor but not the coil. But *someplace* there is a very happy medium to where the wave will gladly pass through the coil and capacitor together side by side. This is called a tuned circuit. A perfect Capacitor and Inductor match that will only let through one frequency or wave, and all the rest fight so much, they cannot pass through either one.

[Boz61]

Dwayne,
Not to take anything from your artistic abilities, here is a Pic of common symbols.
17391

[Boz61]

I've been trying to get through the 2012 edition of the ARRL handbook. It's overwhelming trying to get a grip on all of the theory, I'll probably have to go through it several times before it sinks in.

[Dwayne]

I've been trying to get through the 2012 edition of the ARRL handbook. It's overwhelming trying to get a grip on all of the theory, I'll probably have to go through it several times before it sinks in.

Well Boz,

Maybe I can help you a little on it. I will try to make this thread simple, yet detailed enough to allow you to understand what is going on.

[Dwayne]

We now know what radio waves like for traveling. . . .any wire there is, as well as in the air.

We now know what radio waves do NOT like. . .they hate tuned circuits that are NOT tuned to their frequency.

There is a formula for a tuned circuit. It basically says:

At a certain frequency (tuned circuit), if the inductance goes down, the capacitance must go up to compensate, and vise versa for that frequency to travel through it easily.

Another way how to think about it. . .You are in a car, and your car is "tuned to " 100 MPH. . .you have a certain amount of gas going into the motor to keep it going at 100. If a strong wind starts blowing you from behind (more inductance), you have to let off the gas (less capacitance) in order to keep at 100 MPH.

We now need to know how to amplify a wave. In comes the Transistor or Tube.

In Picture one is a Tube (left side) and Transistor (Right side.) This is the simplest of all tubes and Transistors, but it doesn't matter, they all operate upon the same principal.

You have a input, a "gate" (not really a gate, but I will call it one for now, ok?) and a output. The transistor as a Emitter, Base (gate), and collector. Sometimes E,B,C as initials.

Think of a transistor as your car engine controller. . ..the "gate" is your foot pedal. Your collector as your RPM of your engine controlled by the Gas. and the Emitter as your Gas source.

If you have very little or no gas going to your engine, your engine will either not run, or run very slowly. If this is true, that means your base (Gate that allows gas to flow to the engine) is not being pressed upon with your foot. If your engine is running, and your foot is not on the peddle, then you know your gas control device (Transistor) is leaking, and is bad.

You have all of this gas source just waiting to make that engine scream (It is all waiting at the emitter) , but because you have not "tickled" the base of your controller (opened up the gate to allow fuel to flow), your engine just sits there, because at the collector there is no fuel.

The very second you touch that base (gate), you start to allow some of that fuel to flow from the emitter, through your restricted gate, and to the collector. . .which the engine receives that wonderful fuel from the collector and runs. As you press more and more on that base (open the gate even more) the fuel flows more freely, and the engine revs to life faster and faster.

This boils down to a simplistic game of using very little movement to get a LOT of life out of your engine.

Your simple (very small foot movement of 2 or 3 inches) results in a HUGE increase of energy. In other words, the amount of work you did to push that pedal down, created 100's of times more power. What you accomplished was a amplification of your power!

A transistor is just that, a amplifier. A tube is just that, a Amplifier (most tubes are amplifiers). What we do, is take a very small and WEAK radio wave, make that radio wave "tickle" the base (Gate, or flow controller), and in turn, that allows a much greater flow of current through the transistor, causing amplification. The amplification is a exact duplicate of the wave that is tickling the base (or gate), but much stronger or bigger. This is shown in Picture 1, the second set of pictures down.

The picture shows the Grid of the tube, the base of the transistor, or the flow control (gate) being tickled by a very small A/C wave. The output result is a larger wave that is a amplified version of the smaller wave. (All Professionally drawn by me. . .:D )

Post #4 has the picture for this post. It will show the small wave just under the tube and transistor, and below that, a larger wave.

[Seamaster]

Not seeing a picture in post #9???????????? Enjoying your thread on radios, interested in the topic, can't say I have the knack to understand it all, very frustrating indeed. Hard for me to visualize what I can't see, Keep it up.

[Dwayne]

Oscillation is simple. . .

We only need to take the output of a transistor or tube, and feed it right back into the input of the transistor or tube.

When this happens the stronger output of the transistor is fed right back into the base (or gate controller), and this stronger signal gets amplified even more!... When it gets amplified even more, it is fed right back into the base AGAIN. . .until it becomes so strong it Oscillates.

If it Oscillates on a audio frequency, everyone in the room screams their heads off, clamps their hands on their ears, and looks at the crazy fool who decided to cause such a horrendous piercing sound to come out of the speakers. The next thing you hear is "Sorry about that".

Well, in radio's we WANT that Oscillation ONLY (and IF ONLY) we can control it. If we cannot control that Oscillation, we run into problems.

If we take the output of a transistor or tube, and feed it into the input, we will cause oscillation. . .only problem is: At What frequency? At Many many different frequencies! We don't want that. . .We want ONE frequency.

How can we choose that one frequency??? Our tuned circuits! If we put a tuned circuit between the output and input of our transistor, it will Oscillate, but the tuned circuit will kill all other frequencies except the frequency we chose to allow our tuned circuit to let through.

We now have an Oscillator, with our amplifier, that we can specifically choose what frequency we want it to Oscillate on. We have our very first TRANSMITTER!

Notice in Picture 3.

We have a transistor. . . I have drawn arrows showing the feedback going from the output of the transistor (collector) to the emitter of the transistor (gate). Notice also the feedback is going through a funny picture. That picture is a crystal.

What has happened, is that the person who made this schematic, decided he didn't want to play around with a tuned circuit on the Oscillation, so he used a Crystal instead.

Back when I first became a Ham, Novices were NOT allowed to use a tuned circuit or VFO to change frequencies. They were only allowed to crystals. Thus, Novices always had crystals, and the higher level people had VFO's. My first radio I made was a EICO 720 Transmitter. It was crystal controlled (exactly like this diagram) for the novices, and on the back of the radio was a switch. When you upgraded, you could flip this switch, throw away your crystals in a storage bin, plug in your VFO (where the crystal went), and change your frequency all you want.

What is this saying? This is saying that a VFO *is* a transmitter!. . . and it definitely is! it is a transmitter that uses a tuned circuit instead of a Crystal, like my old EICO.

Also notice I circled the output of the transistor and the input of the transistor.

One other thing. . .there is a Capacitor just before the antenna. Remember what I said about capacitors? to big or to small, the frequency will have a harder time gonig through it? This is a variable capacitor. . .to adjust the output of the transmitter for the maximum output to the antenna.

Not only does it adjust the maximum output, but it also "Isolates" the Oscillator from the Antenna. If this Variable Capacitor was not there, the antenna would be connected directly to the output of the transistor. . .that can be good, or it can be bad. It is bad, *if* the antenna draws too much away from the output, and stops the Oscillation. . .that means a dead transmitter.

There you go. . .step one of a very simple transmitter. No frills, it turns on and off a carrier, so it is wonderful for Morse code. Hooked up to an antenna, you can talk 1000's of miles under the right conditions. 100's of miles easily. Granted it is morse code. . .but it *is* a transmitter. It is the most important part of a transmitter. If it stops working (However delicate it is), you have a dead transmitter.

It is easily built in less than a hour, fun to play with, you can use alligator clips to hook it up or solder. You can try putting it on a circuit board. Cost is about 2 dollars if you leave out the big variable capacitor and replace it with a small fixed capacitor.

I will expand on this later. . .

[Hosana]

I'm with you Boz. I'm trying to get a grip on everything I'm reading in my tech. book.

What the heck happened to the memory I used to have???

[Hosana]

Going from what little I know. I see the battery symbol, antenna, transistor, resister, capacitor, is that a gate or single pole throw at the bottom left?

[Dwayne]

Going from what little I know. I see the battery symbol, antenna, transistor, resister, capacitor, is that a gate or single pole throw at the bottom left?

That is actually a single pull. .. .They made it to look like a
"Key" for morse code.

This is a very simple Oscillator, and that "Key" or Switch turns the Oscillator on and off.

They added a capacitor between the Oscillator and the antenna, so that the antenna will not draw too much power from the oscillator and kill the Oscillation.

It is very good that you all recognize the components. If you have any questions PLEASE ask!

I hope I showed how the transistor Oscillates, by drawing arrows around to show the output feeding back into the input.

And that the Crystal was used in place of the tuned circuit.

[Dwayne]

What is neat, is that you can add another transistor to amplify the signal even more, making it a two transistor Transmitter. . .

You can keep adding transistors to keep amplifying the power.

But you do run into one big problem. Yes you are amplifying your little Oscillator into a real radio, but you are also amplifying "harmonics" and other signals that are "residual" signals. (junk stuff)

How do you get rid of that waste stuff? With a tuned circuit!. .. By placing a tuned circuit inbetween every amplifying stage you have.

[Dwayne]

All Radio's and all receivers have "stages". They are usually drawn in block diagrams to show the different stages. The better the receiver, or the better the transmitter, the more stages it goes through. . .

All of those stages are some kind of amplifying stage or filtering stage. . .

Here is a simplistic Transmitter broken down into stages:

Oscillator -> Buffer -> Amplifier -> tuned circuit -> Amplifier -> Tuned circuit -> final amplifier -> Pi- network (heavy duty Tuned circuit) ->Antenna.

The Buffer is just a simple capacitor separating the oscillator from the first amplifier. It is used to make sure that the first amplifier doesn't draw too much of the oscillation away, killing the oscillator. . which in turn. . kills your transmitter!

A Buffer is like the tinder you put on a match before you start a fire. When you strike a match, you do not attempt to light a log with it. . .it will burn out before the log gets warm.

So. . you caress that valuable match flame by feeding it tinder. This tinder helps that flame get bigger and hotter without putting it out. In turn, that tinder is fed with more and better tinder, until it becomes a hot enough fire to stand upon its own. Same with a Oscillator. . .you need that power (however weak it is) to be taken care of , kept going, and caressed while you buffer and amplify it to a stronger signal.

Sometimes they will combine different section into a smaller section, with the understanding that the section will automatically have a buffer and tuned circuit in it.

Oscillator -> Buffer -> Amplifier -> tuned circuit -> Amplifier -> Tuned circuit -> final amplifier -> Pi- network (heavy duty Tuned circuit) ->Antenna.

becomes:

Oscillator ->1st Amplifier->2nd Amplifier-> final amplifier ->Antenna.

[Dwayne]

Back in the olden days, we discovered radio waves.
We learned to work with radio waves and build transmitters and receivers.
When we built these radio's, we were sloppy. We had long wires running all over the place.

Well, these long wires were actually antenna's too! They were very POOR antenna's, but they WERE antenna's.

Law of physics says: The higher the frequency, the shorter the antenna need to make it radiate efficiently.

So. . in the beginning, we were working with radio frequencies of 3 mhz, 7 mhz. 14 mhz. These frequencies (especially the 14 mhz) created problems for us. The frequency was high enough that the wires we used to build these radios started Oscillating on us! That was a BIG No no. We didn't want this Oscillation! We only wanted our little itty bitty oscillator that WE built for OUR frequency. . .Not some unwanted fly by night accidental Oscillation that ruins our radio's. (Kind of like the unwanted Oscillation in a PA system, the kind people clamp their hands on their ears type).

This means the wavelength of these frequencies were EXTREMELY SHORT with the materials that we used to work with back in those days. Thus these frequencies were "WAY OUT THERE", and beyond the usable and stable range of that era of radio. Thus, we called them "Short Waves". And the name stuck. And even though these waves are considered extremely EXTREMELY HUGE(as in long) in todays standards, people still know them as "Short Wave", or Short Wave Radio's.

----------------------------------------------------------------------------------------------------------------------------

What is so good about the different waves?

the lower frequency, the longer the wavelength. The higher the frequency, the shorter the wavelength.

This also means the higher the frequency, the HARDER it is to work with!
1. It is harder to make a amplifier that will not cause unwanted oscillation.
2. It is harder to narrow down a specific frequency.
3. It takes more energy to work at the higher frequencies.
4. Even the circuit board tracings become little antennas that can cause problems.

So, We pick a LOW frequency that is very very easy to work with. . . in comes 455Khz. It is sometimes called a IF frequency, or an Intermediate Frequency. With this frequency, we do all of our amplification and dirty work with, because:
1. It is so stable,
2. It is easy to narrow down a specific frequency.
3. It takes less energy to work with
4. There are no transmitters that use this frequency.
5. The components are not overly small or overly large.

But HOW can we get a 7 mhz frequency down to 455hz frequency?

It is called interjecting.

Frequency is like math. . .we can add frequencies together and subtract frequencies together. The resulting frequency is not as STRONG as the two frequencies, but who cares? We can amplify it!.

So. . .

in our receiver. . .

We have a very VERY weak 7 mhz frequency at our antenna.
We use a tune circuit to Isolate that 7 mhz frequency all by itself.

We make a Oscillator and use a tune circuit to make a specific frequency of 6.545 (7.mhz - .455 mhz). And we interject that 6.545 frequency in with the radio wave to make .455 mhz!

But, at the same time, no only does it subtract, it also adds! So we also get 13.545 mhz too! But we can choose which frequency we want with a tuned circuit, remember? So we choose the .455 instead of the higher 13.545.


Then we can amplify that .455 mhz as many times as we want, without having to worry about feedback, unwanted Oscillation, and all the bad stuff that comes along with the high frequencies.


Radio's (Transmitters or Receivers) that use a IF frequency usually are a much much higher quality radio's. Better transmit, better receivers, better sensitivity, better everything. BECAUSE they are using a frequency that is easier to control and amplify.

[Dr Dave]

So that's how my favorite component of motherboards, the toroid inductor works. Thanks Dwayne! I always thought it was cool the solution was a little coil of wire on a metal doughnut, but I didn't know how they worked; SWEET!

[Dwayne]

So that's how my favorite component of motherboards, the toroid inductor works. Thanks Dwayne! I always thought it was cool the solution was a little coil of wire on a metal doughnut, but I didn't know how they worked; SWEET!

Yes, that is exactly correct.

Not only that, that same toroid (that is what that donut is called) is sometimes used as a Isolation device. Remember how we use the capacitor to isolate the Oscillator from the antenna, so that the Oscillator will not die? You can do the exact same thing with that toroid. Just wrap a few wires around the toroid in the tuned circuit, and you have tapped onto your Oscillator without connecting to it directly.

Presto! It has been used as a transformer. It transforms a small amount of the Oscillator energy to another wire via inductance. With that wire, you can attach your antenna, or amplify it even stronger.

[Dr Dave]

Dwayne, I think I just fell in love with you.

[Joe B.]

Dwayne, I think I just fell in love with you.Uh oh. :psycho: Man I have to tell you all, it is really just voodoo and a guy was shrunken by a mad witch doctor and trapped inside that box and made to imitate noises and voices and talk back to you. There is no such thing as radio. It's only magic. :doom::bolt:

[Dwayne]

Dwayne, I think I just fell in love with you.

You ain't going to get me to go to teh Chick-Fa lay kiss in. . .;):D:D <chuckle>

I am happy to help out. . .Hopefully some more people will get interested, and start getting a ham license, and play around with electronics.

It is rather fun to do, and it is very cheap also.

Let me tell you what I did last month. . .

I restored so very old Receivers. The cost to me? probably about 3 dollars, maybe 5. These exact same receivers on Ebay sell for about 200 dollars a piece. 2 of the three receivers were given to me for free many years ago. One I purchased because it wasn't working. I ended up selling them. . .150 each. I had about 3 to 4 hours total work in them.

My best. . .I have always wanted the "Cadillac" Hammerlund receiver. . . I was going to purchase one, so I went on ebay with my new earned money. I saw one. . .Ah ha!!!

So, I put a 400 dollar bet on it. (realize this radio is all tubes).

The bidding continues. . .400, 500, 600, 800, 1000,1200,1300,1400, 1475.00! MY Cadillac radio that I WANTED!!! Yeah, it was in excellent condition, working, and the works.

So I searched again. . . Found another one!!! 800+ dollars. I searched again. . .It was up to 1000 dollars and was pulled.

So I searched again. . .50 dollars starter. . .Description was not good:

Receiver DOES NOT WORK!! The tubes light up, but there is absolutely no sound, buttons turn, but only lights up.

Hmm. . .So I put a top bid of 200 dollars on it. . . I won it at 155 dollars. 200 to my door.

Brought it home (it was shipped to my work place), 4 hours later, it was singing, playing music, receiving the ham bands, and is the best receiver I have in my collection. I spent a total of about 10 dollars on it, to get it working.

How much is the radio worth? Hard to say. . . But I am sure I can sell it easily for 500 dollars. But I would rather use it, and enjoy it.

Same can go with those old Radios that are AM and Shortwave. They may be tubes, but you can pick them up for 5 bucks not working, a hour or two, presto. . have a 50+ dollar working radio. And if you want to, give it as a gift to some of your family! Most people love receiving radio's of yesterday that actually turn on and play.

[Dwayne]

Here is a picture of a two transistor Radio.

Back on one of my posts, I described a Transmitter, Here is how I described it:

Oscillator -> Buffer -> Amplifier -> tuned circuit -> Amplifier -> Tuned circuit -> final amplifier -> Pi- network (heavy duty Tuned circuit) ->Antenna.

In this picture, I circled the parts of the diagram.

First circle is the Oscillator. They *again* used a Crystal instead of a tuned circuit for the Frequency. You can see the crystal. . It called Y1, located just under the letters OSC (Oscillator).

But, if you notice, that Oscillator is immediately followed by a tuned circuit! It uses a coil and a variable capacitor "C1" You can see how the tune circuit is in the classic capacitor inductor coil that I have been drawing.

In comes that round donut shaped toroid.

I mentioned that we must caress that Oscillator, so that it will keep oscillating. My drawing used a small capacitor to "tap in" to the oscillation. When doing so, that tap of of oscillation went directly to a transistor for amplification.

IN this diagram, they tapped off the tuned circuit with a piece wire turned a few times around the coil. The wire wrapped around the coil isolates the amplifier from the Oscillator. In other words, this is a buffer between the amplifier and the Oscillator.

So far, we have the Oscillator, the tuned circuit (gotta make sure we get only 1 frequency!) , the wire that is wrapped around the tune circuit is a buffer.

And where does that wire go that is wrapped around the tuned circuit coil??? DIRECTLY to the next transistor to get amplified! The 1st amplifier.

And what does the 1st amplifier have on its output?? ANOTHER tuned circuit that is EXACTLY like the one on the Oscillator! We want to make REALLY sure we want that one specific frequency after we amplify it. And on that tuned circuit, we AGAIN wrap a wire around it, and attach a antenna to it (instead of another amplifier).

So, we have the following things happening on this circuit.

1. Oscillator.
2. Tuned circuit
3. Buffer wire (so we don't kill the Oscillator)
4. 1st Amplifier (the buffer wire attaches to this)
5. ANOTHER tuned circuit EXACTLY like the first one.
6. Buffer wire (which will have a much stronger signal)
7. A antenna to radiate this signal. (we could have put another amplifier in there, but decided not to).

[Dwayne]

What happens if this thing doesn't work? There are 30 components that can go bad, and lots of things can happen.
I would go about it this way:

1. Is there 12 volts being applied? (Do you have 12 volts to the circuit? If not. . gotta fix that.

2. Is it Oscillating? Get a Volt/Ohm meter, touch it to the collector or output of the Oscillator. . .is it twitching/shaking back and forth, or moving funny? If yes, then you are Oscillating. If not, then why? Is the transistor of the Oscillator good? Check that! if that is good, how about the connections around the Oscillator? bad solder joints? misswired? Is your crystal good? Is your tuned circuit working ok? try changing that variable capacitor C1 and see if it oscillates.

3. If it is Oscillating, is it amplifying? Check the amplifier transistor. You can read the voltage at the base of the transistor (which is the input), and you can read teh voltage at the collector of the transistor (which is the output) That output should be much greater than the input! If it is not, than maybe your transistor is bad.
bad solder joints? everything hooked up correctly? Did you use the wrong transistor? did you forget to wrap a few turns around the tuned circuit, to tap off of it to get some signal to amplify? Try adjusting your tuned circuit on your amplifier. . .it may need adjusting for maximum output.


Anyhow. . .this is a very simple transmitter. Drawn up by someone, shows the different elements, can be shown with block diagrams of the different stages, and will work. This diagram is exactly like the huge schematics that scare the heck out of people. They only scare people, because they don't know how to break it down into the basic elements. When broken down to the basic elements, you can ignore all the other components. Those components are only there to make it more stable, Oscillate better, keep the fragile components from overheating, breaking down, and/or help it amplify better.

Once you Isolate what is not working (start from the beginning, you can focus on the component itself, or the components around it.

[Boz61]

Where is the on/off switch? You make it sound easy, but all those different values and elements just make my head hurt.

Thanks again for sharing!

[Dwayne]

Where is the on/off switch? You make it sound easy, but all those different values and elements just make my head hurt.

Thanks again for sharing!

the on and off switch is in the very FAR FAR lower right hand corner. It has two switches off the same switch. . .It is called a single pull, double throw. It is S1 and S2 in the diagram. What happens, is when you turn on the switch, BOTH s1 and s2 move at the same time. S1 lights up a little lamp to tell you that there is power, S2 connects the second little lamp to ground, so that when you key up the radio (on the far lower left) that second lamp will light up when you key.

fantastic question!

Thus, you have two lamps. One to tell you that your power is on, and the transmitter is ready to sing, and the second lamp will light up as soon as you press the morse code key, telling you that the morse code is working.

[Hosana]

Man, this is very small stuff to work with. I can pick out alot of the pitch forks (grounds). When I walk into our company radio room there is this magnify glass about the size of a dinner plate. Now I know why.

Is this transmitter one of those Pixies that fits in a altoids tin?

[Dwayne]

Man, this is very small stuff to work with. I can pick out alot of the pitch forks (grounds). When I walk into our company radio room there is this magnify glass about the size of a dinner plate. Now I know why.

Is this transmitter one of those Pixies that fits in a altoids tin?

This can easily fit in a Altoids can. . . very easily. Push comes to shove, you may be able to fit it in a click ink pen if done properly. Only you would have to use a tuned circuit instead of a crystal. :D. But they DO make mini Crystals. . .that would fit in a pen easily. I think it would be fun to try. Imagine having a pen as a two transistor transmitter. . . I have seen worse. ..:D

[Hosana]

This can easily fit in a Altoids can. . . very easily. Push comes to shove, you may be able to fit it in a click ink pen if done properly. Only you would have to use a tuned circuit instead of a crystal. :D. But they DO make mini Crystals. . .that would fit in a pen easily. I think it would be fun to try. Imagine having a pen as a two transistor transmitter. . . I have seen worse. ..:D

This is beginning to sound like James Bond stuff:). Even though I've read about electrical components and what they are I was still wondering how they actually worked. I would say the timing of this thread is perfect. Thanks for sharing.

[Dwayne]

Here you go guys and gals. . .

An amazing circuit. . . the most simplistic transmitter of all.
. .

I have not built one yet. . .but. . .i think I am going to do it for the fun of it. . .

This guy routinely talks 5 miles with no sweat. . .has talked 100's of miles in the right conditions.

http://sparkbangbuzz.com/zinc-osc-2/zinc-osc3.htm



Here is a link to the website. . .