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Vaporware posted:Hey, I was really interested in old radios for a while. I have an old philco 1942 and I was going to repair it, but I ran out of enthusiasm waiting for the parts to arrive over the months. Don't be a loser and quit when you've gotten this far. First, if you have an AM receiver, tuning is NOT that sensitive. When you put the new caps in, you MAY have to tweek it, but usually you don't. Why? Unless you changed out mica caps in the tuned circuit, other component changes are not going to affect it that much. If you are talking about an AM receiver, lead length is not important. Second - Are you talking about an old FM receiver, with the FM band down in the 50 MHz range? Those radios were usually AM and FM band. Photos please. Third - 1940s and up radio receivers are simple. About that time, everybody settled on about the same electronic design. Seriously, you could pick up any radio from that era and except for a resistor here or capacitor there, it was the same. Fitting another radio inside and making it look seamless, that is tougher. Fourth - LOTS of people fix up old radios. If you do decide to sell the set, go to rec.antiques.radio+phono newsgroup. The buy, sell and discuss old radio repair here. But, seriously, you put the cash in - fix it already. It is as simple as this: (1) Get the schematic (2) Clip out the first paper cap the cap's body (3) Make tiny hooks out of the remaining leads (4) Solder in your new capacitor (5) Repeat 2-4 until all paper caps are replaced (6) Section by section, replace the filter cap (7) Check the resistance of any series-dropping resistors in the power supply circuit. (8) Turn on radio, and apply 120 AC - or better yet, get a variac and SLOWLY bring up the line voltage, listening/smelling for problems. (9) Troubleshoot issues (10) Success. Talk to the guys that newsgroup - this is all they talk about. And don't give up.
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Sep 5, 2008 18:35
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Here is one of my projects - a AM/Shortware radio receiver made by the Hallicrafters Co.  I work on it during lunchtime. So far, I've replaced all of the paper and electrolytic caps, out of tolerance resistors and bad tubes, cleaned the case and chassis, replaced the dial cords and lubed all the moving parts, rewired the AC to reduce the hazards of 'hot chassis' and tested it by tuning to WBZ (our local 50kW AM radio station - you can recieve it on a water pipe and a diode). The volume pot is really scratchy, and tuning of the oscillator and rf coils was 'vauge'. I'm at step (9) of my list. Once I am done, I'll have a nice shortwave radio to put on my bookshelf in the office.
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Sep 5, 2008 19:01
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Vaporware posted:I can't remember the freq range. edit: Philco cut costs WAY DOWN on their radios, as a result, they always need more work to get going. And, you are working on one of those big ones... Still, replacing the wiring isn't that bad. Projects like this work better when you only take on 30 minute - 1 hour of drudgery (like replacing every wire...), patience is key in this hobby. quote:The cabinet on the other hand is mighty fine. I had a family friend refinish it, which I know destroys the value, but this is a common model and the veneer is very beautiful. Plus it has drink rings and such on the top and needed a good resealing. Radio cabinets aren't 19th century furnature. They all were built cheaply, and usually look like junk after storage in a humid basement or garage. Refinishing is common, and improves the value for most any radio of this type. You need silicone oil. You only need to take care with the wiring for the high band, before the IF mixer. Everything after that mixer is non-critical. HiroshigeStations fucked around with this message at 19:48 on Sep 5, 2008 |
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Sep 5, 2008 19:28
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Nerobro posted:ASM seems the most sane way to program PICs. :-) I can actually read it... FLOWCODE is pretty good, you can write code as a flowchart. Writing code for a SMART battery calibrator was very quick. You can compile to C and to the HEX, ready to program onto your PIC. (nuts, no WAFFLEIMAGES...) HiroshigeStations fucked around with this message at 17:46 on Sep 9, 2008 |
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Sep 9, 2008 17:39
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For what I needed to do, it did it very well. For about 4-5 hours, I have a box that calibrates my batteries, as I intended. The programming isn't that sophisticated (loops, branches, and such) - but I see that modules exist for working with TCP/IP, Bluetooth, and a variety of serial buses. Great feature is that it is self-documenting; all of your variable names and comments from the flowchart are copied over to the C; it is readable code. You can never have one disagree with the other. HiroshigeStations fucked around with this message at 02:27 on Sep 10, 2008 |
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Sep 9, 2008 22:29
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mtwieg posted:I've nothing against higher languages. I wish I could use them, but I'm not that great in C. But knowing assembly allows you to be much more in touch with your hardware so you know what is truly happening. It's also inherently more efficient than compiling from higher languages. If you are trying to squeeze out as much performance as you can from the hardware, then you can do no better than assembler for optimizing your code. However, trying to do a very complex task entirely in assembler seems a bit masochistic. The optimization in a good C compiler is going to get you pretty close, you can tighten up areas using assembler macros. Of course, if you are doing something that contains simple elements, and you need/want to bang it out quick, tools like Flowcode are a dream. Sure, the beauty for knowing every corner of your micro, writing tight code, and fitting the program into a tiny space is attractive, but sometimes it is such an impediment to reaching that much more attractive thing - finishing your creation. This discussion is starting to belong elsewhere...I vote for the oscillators.
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Sep 10, 2008 15:02
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babyeatingpsychopath posted:So, something besides MCUs is cool with me. I really dig transistors. I think MOSFETs are cool. Things best left unsaid on a date...
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Sep 12, 2008 06:13
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Cyril Sneer posted:Short of taking note of each and every tube variety, is there a way I can learn about different tube specs, and what ones are generally considered "useful"? Can't short-cut experience. You got to come in knowing what you want for a project or to maintain/upgrade what you got. You go in just picking this and that because 'I can build a camera out of this" or "this is a tube used on Fender amplifiers, and they rock", then they will sit unused in your storage-area-of-choice. While the tube is important, its an inert piece of glass without of the rest of the equipment to run it. These projects fail: Hey, I'm new to this, but there is this cool tube. I'm going to build X... Same sad result, wasted money, good parts rotting in the basement, and said person working harder on justifying why they didn't finish then on overcoming their lack of knowledge and finishing said project. My advice, unless you are looking to collect tubes, wait till you actually have a need for them. Find a circuit to start with, one somebody else has already built. Be willing to spend the cash to finish - account for tools, nobody figures the costs of chassis punches and filament/plate transformers. Better yet, get one of those really cheap 50's AM radios and amplifiers and mess around with them. If you see any 6JS6, PM me. I need them as spares for a transceiver. Lastly, https://www.tubedata.org and cheap 12AX7s, 6V6, 811, 807, and 0A2. HiroshigeStations fucked around with this message at 05:10 on Sep 14, 2008 |
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Sep 14, 2008 05:07
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Unparagoned posted:It's a TENS machine. That voltage is fairly standard for tens machines. I have a working circuit, it's just I wanted to see if I could improve it. See what they did here: 
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Sep 16, 2011 14:43
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Unparagoned posted:Yeh. The two roles of that transformer is quite neat. Why you looking at the power supply? Look at the output.
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Sep 18, 2011 02:17
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| # ¿ Apr 28, 2024 07:19 |
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taqueso posted:R.I.P Bob Pease
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Jan 2, 2012 01:51
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