Indirectly heated diode valveEarly diode valves used a directly heated cathode. This consisted of a heater element that also acted as the cathode. This significantly limited the operation of these devices. Read.The solution to both issues was to use a electrically separated heater element that was used to heat a cathode.

They have the basic theory of the vacuum tubes used in the AR102 and TRA - 8. Students should be able to associate the schematic symbol with the physical.

This method known as indirect heating is almost universally used for all valves whether they are diode valves, triodes or whatever. Half wave diode valve rectifierThe simplest form of diode valve rectifier is the half wave rectifier. It only requires the use of a single diode valve rectifier. However it is not as efficient as some other forms of rectifier.

Valve / tube half wave rectifierIt can be seen that if an alternating waveform is applied to the diode valve, or diode tube, it conducts over half the waveform and not the other. This means that when rectifying AC waveforms it is only 50% efficient as half the waveform is used and the other half is discarded. Full wave diode valve rectifierIn order to make use of both halves of an alternative waveform cycle, a full wave rectifier can be used. In the same way that it can be implemented with semiconductor diodes, the same can be achieved using diode valves. In fact full wave rectifier diode valves are available with one device containing the two rectifiers. Valve / tube full wave rectifierIn the full wave rectifier circuit, different diodes within the rectifier handle different halves of the waveform. In this way both halves of the waveform are used.

Also the fact that the time between peaks is shorter means that smoothing the waveform is much easier.As seen in the diagram, full wave rectifier valves / tubes were available. These contained two anodes and a single cathode enabling full wave rectification to be accomplished using a single valve.A further point to note is that power supply rectifier diodes often used a separate 5V supply, whereas the common standard for the heaters used for the equipment itself was 6.3 volts, although other voltages were often used. Diode valve signal detectorIt was through investigating radio signal detection or demodulation that the first diode valve was invented by Ambrose Fleming.

In fact the diode valve detector can be used for amplitude modulated signals.The action of the diode valve rectifier can be seen below where the amplitude modulated signal consisting of the carrier of varying amplitude is demodulated. To recover the modulation, the signal is rectified and then the carrier is removed using a capacitor as a high frequency filter. Signal detection / demodulationThis is a very simple but effective form of AM demodulation, although it does have its drawbacks.

The levels of distortion can be high because the diode characteristic will not be totally linear, and this form of diode detector is also subject to distortion resulting from selective fading - an issue that is apparent on the frequency bands normally used for amplitude modulated transmissions.

You just have to remember that the schematic doesn't tell you anything about where the components are physically located or the order in which various branches of a circuit are connected to a 'trunk'. If you trace a wire on the schematic from beginning to end, there could be five lines branching off in order A, B, C, D, E. If you were to physically follow the circuit on the radio, the order might be C, D, A, E with B branching off of D prior to encountering a component.

When you get to the refugee quarters, two guys tell you there is something off about Atton and from there you get him to talk about the wars.After a bit of effort going through the dialogue trees I managed to turn him into a Jedi on the first planet after Telos, which I hadn't done before. Kotor 2 kreia influence. I got at least one influence part on Peragus, and probably one more on Telos.

B and C might be close on the schematic, but physically on the opposite sides of the radio. Some manufacturers like Silvertone and Philco were usually good about including a second diagram showing the physical location of components on the schematic, without showing the actual connections. If you have one of these radios along with the schematic and physical component location diagrams, you can get a much better idea of what I'm talking about.Bob. Agree practice is the best way. If you know the symbols then you are halfway there.

The lines just shown how they are connected. It helps to know fundamentals of whatever it is you are looking at. For radios, you need a knowledge of what that coil, capacitor, resistor tube is doing, at least in a general way. Just knowing how how things are connected don't help much in trouble shooting, but if you are going to be a re-cap specialist, then all you need to know is 'have I got it connected to the right place?' There are many variations in schematic drafting methods, especially for the older sets before some standards were adopted.

I suggest, as someone else did, that you get a simple radio, get the schematic for it and start tracing, find circuit on schematic and in the radio.There are two popular ways to show when wires were connected together and when they just went past each other. The newer method, pretty much universal after WW2 (1945) is the dot/no dot.If the wires cross without a dot at the intersection, they are not connected. If they butt or cross with a dot at the intersection, they are connected. The older method is that the straight crossover or butt is connected, if the intersection has a half circle as is crosses, it is not connected. There is one more method but have never seen it in radio circuitry.In simple radio schematics, signal flow begins at left and flows right, except the power supply/rectifier which is usually under the signal paths. In more complicated sets, the circuits may double back and flow to the left.

This is subject to MUCH variation, especially in some old schematics. Guys, thank you very much! I understand the basic purpose and function of the components, but not how they translated into a schematic and how to read it.

Your suggestions - and this article - will surely help start me on the right track and already answer a few basic questions I had. I actually have 7 small sets that I'll use to begin practicing on - as you suggest. They all need recapping.You nailed it jkaetzjr, my goal is to reach the recap specialist stage only. Well put my friend.I have a good friend who is 'well versed in electronics theory' and can fix the major problems for me.If anyone else reads this post and has additional suggestions, thanks in advance for sharing them.Joe. Can anyone suggest a good source for explaining how to read a schematic to an electro-newbie?

I've found plenty of sources that generically explain the symbols used etc. (which I understand by definition), but nothing that provides examples of how to read and, for example, compares a schematic to a chassis to illustrate. Sorry if this sounds stupid, but very eager to learn and understand them better. Any guidance would be very much appreciated.

Thanks.The basic art of it is really following lines around and seeing where they go. The real trick is relating what is on the paper to what is on the Chassis. It takes patients and practice. Some times when they draw it, it looks like it is on the other side of the chassis, when it really is right on top of each other inside the radio physically.

This is very true with old radios. New stuff may be drawn exactly as made, which is a mixed blessing.The basics of symbols are pretty standard, resistor, diode, capacitor, inductor, coil, transistor or tube. To understand what each does calls for some basic electronics education. There are many books and on-line videos and tutorials.I am not kidding, a good 200 in 1 'science fair' kit would be a fun learning tool. They have the springs and jumper wires.

They where sold at radio shacks. They don't make them any more, but Ebay has them used. You can buy modern versions of these learning kits.To understand what you are looking at and why a RF circuit has a coil, tube there and a capacitor over here is another story. Google is your best friend.There are different levels of reading and just knowing this capacitor is connected her and understanding you are looking at a power, RF or Audio stage of the radio.Follow one wire at a time.

Color highlighters help. Just remember if you are working on tube radios there are high voltages. I would recommend working with low voltage transistor circuits at first. When you get into transformers and capacitors it can kill you.

To properly read a schematic you need to be well-versed in electronics theory. There is no other way to do it correctly.Welp. I wouldn't go to that extreme. Thats like saying you need to be a city-planner to read a gas station map.One of the best exercises is to reverse engineer a radio.

Take a highliter pen and work backwards from the actual circuit onto the paper schematic. Each tube pin is a starting point. Follow it to all of the destinations regardless of your interpretations or knowledge of electronics.You'll soon get the gist of how things are drawn on paper. Once you have a sense of how it appears on your paper you'll have a much better sense of how it compares to the actual radio. Little clue lights will pop up everywhere because you have 'been there' before. Jayyoungs, hi. Its not all that different from power wiring.

The trick is to know the components and the components terminals. By components I mean resistors, capacitors, coils, transformers and sockets (tube, speaker, connector). The hard part is translating to the physical layout of chassis. Its not the straight lines you see on the schematic. One basic is that the components rarely, if ever, are spliced, that is they go to a terminal on some component. They usually are connected at tube sockets and some times a terminal stripe.

For cost purposes they tried to avoid terminal stripes and would use instead an un-used terminal on a tube socket. Point to point is a good way to start and remember that components often are the path not wire. Quote: 'To properly read a schematic you need to be well-versed in electronics theory. There is no other way to do it correctly.'

Johnnysan-The world is full of people who do things badly. If you don't believe me, just listen to the news.Why do you think we get so many postings here that read 'Hey, why is smoke coming out of my radio?' Or 'Are sparks normal inside a rectifier?'

TeamViewer is a remote control software primarily used to establish a connection to any PC or server around the world. The software, designed to conduct PC screen sharing & control activities and online meetings, encounters the following error: No connection to TeamViewer server. This morning none of my computers will connect to the Teamviewer Server, even though I have a public IP address which I can ping. The same IP address worked on the system yesterday and I can conect to the internet and to the Teamviewer website (obviously!!). Windows 8.1/10, Teamviewer 12, no proxy. No connection to TeamViewer Server - Please check your internet connection I'm using TeamViewer v12 on windows since a long time and have no problem with it until this morning. 2 stations: one desktop at home and one laptop at my company. No connection to teamviewer server. Re: No connection to TeamViewer server. OK, there is no solution. The only way to make TV working is to set 'Gnome on XOrg 'desktop at login. Anyway if you have problems that on F24 you did not had. You need to switch to Gnome on XOrg instead of the default Gnome desktop wich uses XWayland.

I think doing a job right the first time (not the last) is important. Everyone is looking for that magic button to push that makes everything alright; they want the easy solution. Well, I hate to rain on your parade, but there is no easy way to fix radios (or the economy, or anything else). Telling newbies that repairing electronics is as easy as tracing wires is like saying brain surgery is as simple as cutting out paper dolls; this advice is worse than no advice at all.Reading symbols on a schematic is only a start; if you don't know the function of elements of a tube and components you aren't going anywhere. Without knowing the fundamentals of oscillation, modulation, rectification, amplification and demodulation you will simply be a parts subber. Johnny - you're right - I'll quit and toss these old radios of mine.Come to think of it, I'm now embarrassed to realize I've been refinishing antiques for 30+ yrs without a chemistry or forestry degree and just following some great early advice and hard work to practice - what the heck was I thinking??!!

I'll need to stop rebuilding '60s era Ford engines and trannys, too - amazing I'd figured out where all those darn spark plugs go!! And the most amazing - so ironic that friends kid me about being such a perfectionist on my projects.

I'm sure glad you showed me the 'light'!If I'd wanted the easy way and not learn it - I'd not posted for help. Go ruin someone else's thread and gripe about the economy.All you other guys, thanks for the help. Traced and highlighted my first schematic against a GE 515F late last night.Joe. Speak the truth and people will hate you forever. Some things never change.Some of the newbies here have really applied themselves and studied electronics to the point where they can effectively repair radios; some just want quick answers as to why their radio 'makes funny noises'. I've been a tech for 36 years, and I will admit that many things can be 'fixed' by stumbling around and replacing parts at random-this is also a good way to produce smoke clouds.Jayoungs first post stated that he is 'eager to learn'; I took him at his word. 'Tracing wires' is not radio repair; learning what the symbols are is only a start.

My point still remains: learn the basics of electronics. Knowing how radio works will do wonders in diagnosing and troubleshooting to component level.

This is infinitely better than listing an un-repaired radio in the Classified section as a 'parts set.' Like Bob, I've read several of the Marcus & Levy books with appreciation. However, for learning to read / understand schematics, the best book I've seen (by far) is 'Complete Guide to Reading Schematic Diagrams' by John Douglas-Young. I have the second edition, 1980, and it covers both tube and transistor circuits. He uses a 'Circuit Analyzer' base diagram to break down the functions.

It encompasses the 'active element', the 'input', 'output', 'common' and 'load' sub-blocks to describe - in a consistent format - how the elements act / interact. He then goes on to discuss Power amps, oscillators, modulators, demodulation, power supplies and numerous other categories of circuits. (It's a 300 pg book.) For instance, the Regenerative Detector is a typical discussion covering two pages. He discusses: a function summary, distinguishing features, uses, detailed analysis of the sub-circuits (here: DC sub-circuit, AC input circuit and AC output circuit) and finishes up with circuit variations. A very nice, structured way to learn to read schematics. Found mine for $3 at a book store - check out Alibris and Abe Books.

I've bought other books of his on the strength of this one and have not been disappointed. Best of luck, Tom.

Complete Guide to Reading Schematic Diagrams' by John Douglas-Young. I have the second edition, 1980, and it covers both tube and transistor circuits. Tom SHere's one source for that book Tom mentioned.In another thread someone mentioned these books helped them out. Info from the same source.While your waiting here's a few links you might want to check out:Down the line you might be lucky enough to grab a hard copy of 'The Elements Of Radio Servicing' by Marcus and Levy pretty well a standard in servicing advice. E version in the ArchivesWere all learning no matter what stage we're at. (I've been doing Electronic service repair for over 25 years).

The day you stop learning something new is probably the day your dead.Nothing wrong in asking for advice.RegardsKenLast edited by on Aug Wed 26, 2009 2:05 pm, edited 3 times in total. I learned electronics, starting at about age 11, in a very unorthodox way. I started experimenting, with no knowledge of theory at all.

Got plenty of shocks, and probby should be dead. Then I started reading Popular Electronics, then some radio servicing books.I remember I built a Knight Kit 18 watt amplifier when I was about 13, and by then I could sort of read schematics, but I was struggling to understand how a transformer could get current across empty space, without any physical connection between primary and secondary. Finally, I took Electric and then Electronics shop in high school, and theory started to make sense.In Electric I shop (Freshman in High School) John Warmelink did a beautiful job winding a (step down) transformer, then hooked up the 6 volt secondary (unstead of the primary) across 120 VAC and blew it up.

The teacher, Mr Binstock, let him go ahead, and nobody said anything until the sparks flew! A lasting lesson, indeed!