From FB group Building Transistor Radios 2018-08-24 – The discussion was about the OTL complementary symmetry audio amplifier that Mr. Barnett has posted several times to the group, which uses a 2N3904 and 2N3906. Willie Barnett Let’s talk about current. Suppose your amp has a 9V supply. When the output transistor is turned fully on,
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from FB group Building Transistor Radios 2018-08-22 Olek Kopyto I recently did some tests on 2N3904s I got from Mouser and from a Chinese eBay seller. The ones from Mouser had a current gain of right around 200, right in the middle of the 100 to 300 gain range according to the data sheet. The
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From FB group Building Transistor Radios Wayne Leake Yeah, the 2N3904 is E B C, THE ‘945 is E C B. Watch out the leads don’t touch and short. 😝 I have the Moto HEP catalogs, if you need to find out what it’s equivalent to. When National Semiconductor came out with their catalogs they
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From FB group Building Transistor Radios For those who don’t want to or can’t use a JFET for high input impedance, you can use a regular transistor or two and bootstrapping to get a 10 Megohm high input impedance amplifier. This is from “Common Collector Amplifiers”, Electronics Now, Oct. 1993, found at americanradiohistory.com. For RFs,
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From FB group Building Transistor Radios Nick Cook Have you found the reason for the failure of the 2N176? You could use the NTE equivalents NTE104 or NTE121. These may be expensive but they are the substitutes. But you have to make sure that the new one doesn’t burn out. You should be able to
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From a FB group Building Transistor Radios Markku Vuorensivu Tell me more! I’m all ears! I got a thousand 2N3904 BJTs from Mouser, and ten packs of 100 from eBay. I selected a dozen from each and measured their current gain using two methods: a cheap DMM, and a ‘transistor tester’ which has the ZIF
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From the FB group Building Transistor Radios Willie Barnett The generic 901x series are very cheap jellybean transistors used in consumer electronics, typically made in Asia. The 901x was preceded by C, but other companies used other prefixes such a S901x for Fairchild (now ON Semi), or CC901x, or even MPS901x or MMBT for surface
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Happy New Year! I replied to a comment by George Glavas on FB group Vintage Transistor Radios George Glavas I’ve never read any documents to back up your claim that “…germanium transistors lose gain as they age.” I think that people believe this because old equipment has lost gain. But all of the problems I’ve
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From FB group Vintage Transistor Radios I’ve considered converting a tube set to transistors. The problem is getting tube bases that aren’t sharp and breakable glass. Some old electronics used tube base type plugs for relays and plug-in modules. Then there is the problem of dealing with the higher voltage. Transistors can handle 300V, but
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My answer to a FB Arduino group question on Sept 17 Dan Rogers has the right idea. The protoboard, with all the holes in it, was never meant to be permanent. The contacts in each hole lose their springiness as they are used to hold wires. The contacts can become intermittent after awhile. As time
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