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 Post subject: How many transistors can a transistor radio really use...
PostPosted: Feb Wed 10, 2010 6:50 pm 
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at one time? I heard it said that the transistor radio can only use I believe 6 or 8 transistors and that those 10 and 12 transistor radios are just a marketing gimmick. Can anyone explain this to me.


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 Post subject:
PostPosted: Feb Wed 10, 2010 7:24 pm 
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It depends on the quality of the set. I bought a really cheap 10 transistor set, from E J Korvettes, opened the battery cover and saw some (dead) transistors with all 3 leads twisted together and soldered into one hole, and other (half-dead) transistors with only two leads inserted, used as diodes I guess. Maybe 6 transistors did anything. I took the set back for a refund next day. People could count the transistors, but would not look at the leads.


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 Post subject:
PostPosted: Feb Wed 10, 2010 7:54 pm 
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Johnny, I’ve heard that the “basic” circuit for an AM transistor used 6 transistors and I have and seen many with 7 transistors (those Zenith 500’s w/ P-P outputs) But I do remember as a kid seeing the adds for transistor radio’s with transistor counts from 6 to 20+! and my curiosity got the best of me when I got older and I dissected a few to find that the “basic” circuit was still a 6-transistor radio but other transistors were strategically placed through out the circuit using only two junctions as diodes.

I guess this allowed the marketing firms to advertise these 10, 12 and 14 transistor radios as better than your standard 6 transistor version. (people gobbled this BS up) :shock:

I too remember when IC’s came to be in consumer electronics (two power transistors in a sip package) … all of a sudden they could print IC on the device and people gobbled them up.


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 Post subject:
PostPosted: Feb Wed 10, 2010 8:32 pm 
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Are you talking shirt-pocket radios, or 'proper' portables?

I just did a quick count of some of my better trannies:

Zenith 3000-1 = 12 transistors

Nordmende Globetrotter = 14 transistors

Sony CRF 5090 = 20 transistors

and they're all used for one real function or another, not just "dummy diodes"!

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 Post subject:
PostPosted: Feb Wed 10, 2010 10:18 pm 
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Then there were the "Boys Radios" that only used two.

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 Post subject:
PostPosted: Feb Thu 11, 2010 2:33 am 
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True Ed, and I have 2 transistor Boys Radios from the late 1950's that still work fine, as basic as they are :)

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 Post subject:
PostPosted: Feb Thu 11, 2010 2:41 am 
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I think for AM, eight was enough. That's what the P-780's have and they are stellar performers.

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 Post subject:
PostPosted: Feb Thu 11, 2010 3:00 am 
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iTactics wrote:
True Ed, and I have 2 transistor Boys Radios from the late 1950's that still work fine, as basic as they are :)


I just checked out your website. WOW! :D

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 Post subject:
PostPosted: Feb Thu 11, 2010 3:38 am 
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I believe the number would have changed over time. Early transistors, especially germanium, did not have the gain/stability for very high amplification in a single stage. Later silicon transistors did. I have a superbly performing Heathkit I built as a kid 43 years ago (and it still performs superbly with NO repairs) that has six transistors: RF stage, Converter, IF stage, 1st Audio stage, P-P Power amp.

Earlier radios might have required two IF stages and maybe two audio voltage stages for equivalent performance.

-David


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 Post subject:
PostPosted: Feb Thu 11, 2010 6:28 am 
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Thanks Ed, I'm glad you liked it :)

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 Post subject:
PostPosted: Feb Thu 11, 2010 11:14 pm 
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The Korvettes radio I bought was a shirt-pocket radio. I think the FTC passed a law in the 1960s requiring that transistors had to be active to be counted, or something like that. A few years ago, the law was finally repealed since transistor count is meaningless now. Imagine how many transistors are in modern chips and microprocessors.


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 Post subject:
PostPosted: Feb Sat 13, 2010 10:35 am 
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I would imagine that a 1 transistor radio could be made too.
1 diode and an audio amplifier. :wink:

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 Post subject:
PostPosted: Feb Sat 13, 2010 1:23 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Sandpoint, IDAHO 83864
Radiosmoker- If you want to have some fun and have access to a lot of older magazines, don't overlook the early 1960's issues of Radio-TV Experimenter magazine. I have issue number 569 that I obtained from a fellow ARF member a couple years ago and on page 142 is an article titled "Wrist Radio" by Thomas A. Blanchard. It uses a ferrite loopstick, 1N34 diode, and a CK-722 transistor, along with a single "N" cell battery.

Believe me, that small radio built into a small plastic case that you strapped to your arm works! I built it when I was a kid and had loads of enjoyment out of it. I am intending to build another one just as soon as the loopsticks become available from Bill Turner.

Also if you want a glimpse preview to my first transmitter, it is on page 134 of that issue titled "Transmitter for the Novice" by Alice Rolf, KN5SEL. Only mine was built on a brand new shiny aluminum chassis unstead of inside a surplus ammo can.

That issue is one of the best issues of that magazine there was, in my opinion. It is never far from my reach.
Curt

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 Post subject:
PostPosted: Feb Sun 14, 2010 5:07 am 
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Hey Curt,

Another common memory ! I had installed a variable cap and loopstick in one of those small "snap-close" clear plastic cases to make a "wrist-radio" around 40 yrs. ago as a kid, but never completed it...

Did have a scratch-built one transistor super-regen that worked
well...

Amazed by the common experiences & projects by ARF members...

John


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 Post subject:
PostPosted: Feb Sun 14, 2010 3:53 pm 
Silent Key

Joined: Jan Thu 01, 1970 1:00 am
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Location: Sandpoint, IDAHO 83864
John well the common experiences a lot of us had was because we were all of the same rough time frame and transistors were the new technology at the time. It is sort of amazing that transistors have been now used longer than tubes were. The tube era ran from 1920 to about 1975. A period of 55 years. Transistors have been used since 1950 to the present, 60 years.

Back then boys were always tinkering around doing stuff with electronics and one and two transistor sets were only a natural thing to cross our paths.
Curt

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 Post subject:
PostPosted: Feb Sun 14, 2010 6:15 pm 
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Location: La Porte, IN, USA
How many have you got?
Since basic discrete transistors were initially pretty low gain triodes, I can imagine, using a philosophy like McMurdo Silver's or Scott's or the engineers at Midwest Radio, using at least 10 or 12 effectively in an AM set, or certainly in an AM multiband set. Tuned RF stages, extra IF stages, amplified AVC, AFC, noise limiters, BFO's, not to mention product detectors or even Synchronous detectors--all would be ligitimate uses for extra transistors beyond the 5 or 6 minimum necessary for acceptable AM reception.

Now add FM, and you could double the number.

Of course, in reality, hardly anybody used them like that. In order to inflate the count, unscrupulous manufacturers used extras as diodes, or even just soldered in place but non-operational.

Incidentally,I built a one transistor Knight Kit in the fifty's that would only recieve a couple of strong local stations on a long wire. But the tuning was so broad, it received full bandwidth high fidelity from the local classical station, and I hooked it up to my stereo sytem as a Hi Fi tuner!

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