Archive for the ‘Transistors’ Category:

2018-06-28 Bootstrapped For High Z Input

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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2018-06-20 2N176 PNP Ge Power Transistor Substitutes

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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2018-06-19 2N3904 Transistors Betas

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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2018-06-14 The 9012, 9013, 9014, 9015, 9018 And Similar Transistors

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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2018-01-01 H N Y! Old Germanium Transistors Lose Gain As They Age

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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2017-12-04 Converting Tube Set to Transistors 

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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2017-09-10 How Long Can An Arduino Circuit Last?

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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2017-08-19 Emitter Base Breakdown Can Damage Transistor 

From YT reply to Neilgn  2017-08-20 Take any NPN transistor and measure the gain, and write it down.  Then put a 1k resistor in series with the transistor’s emitter and connect the emitter to positive and base to negative of a power supply.  Adjust the voltage until 2 or 3 volts are across the 1k

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2017-08-15 1950s Astor 7 Transistor Radio

2016-11-21 Goldmine Giant TO92 Semiconductor Asstmt G21402

I got a few of these just to satisfy my curiosity, and to waste ten bucks each and waste time sorting the transistors into piles of the same number. My general observations Most of the datasheets for these transistors can be found online. Most of the transistors are PNP.  I got several dozen, maybe a

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