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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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15th Nov 2013, 9:25 pm | #41 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,528
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Re: "Illustrated Teach Yourself Radio" by David Gibson
Decent current gain and OC44 don't exactly go together..... though leakage current which could do the robbing, might!h
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16th Nov 2013, 12:03 am | #42 |
Dekatron
Join Date: Sep 2010
Location: Cheltenham, Gloucestershire, UK.
Posts: 3,077
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Re: "Illustrated Teach Yourself Radio" by David Gibson
I guess one thing to try would be to reduce the value of the 1meg resistor to bias the device harder if TR1 had low current gain.
If it was built with all silicon devices I think it could be persuaded to function with the original schematic even with the clamp diode D2 in place. But some attention would be needed to set the biasing correctly according to the Hfe of the device. I agree that the blocking cap suggested by G6Tanuki would make the biasing of the circuit far more tolerable of Hfe and would be much more conventional in terms of operating point. It would probably give a higher efficiency too. The only thing it might fall over on would be if the device chosen for TR1 had very high Hfe and TR1 went hard into saturation. But from what you say of germanium devices this would be extremely unlikely to happen.
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Regards, Jeremy G0HZU |
8th May 2014, 4:02 pm | #43 |
Diode
Join Date: May 2014
Location: Guildford, Surrey, UK.
Posts: 4
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Re: "Illustrated Teach Yourself Radio" by David Gibson
Amazing! I am so glad I found this, I have been searching for years (on and off) to find out about this book.
I borrowed one from my local library in the 70's and spend all my pocket money on the superhet....and I got all the colis, IFTs and the 3 gang capacitor for Christmas. Unfortunately it never worked. I have the parts still in my attic, but without the book I have never been able to finish it, perhaps now I will! This book inspired me to become a radio amateur, which I managed in 1980. I have managed to order a copy fo the book, and plan to make this work...and show my children the pleasures of electronics! Rob (Zaxanoid) G8ZAX |
8th Jul 2016, 9:05 pm | #44 |
Octode
Join Date: Aug 2008
Location: Rotherham, South Yorkshire, UK.
Posts: 1,701
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Re: "Illustrated Teach Yourself Radio" by David Gibson
Just found one of my copies of this book and it is the later 1976 edition. Most of the circuits are updated from the earlier version discussed above. Hope the attached is clear enough, no access to the scanner at the moment, but contrast this version with the original two transistor radio.....
Peter |
13th Jul 2016, 9:36 am | #45 |
Heptode
Join Date: Sep 2005
Location: Shoreham-by-Sea, West Sussex, UK.
Posts: 610
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Re: "Illustrated Teach Yourself Radio" by David Gibson
It seems to me that many people read the book and were inspired to take up electronics and radio through it even if they never managed to make a working set. I wonder if the author ever realised how we had benefitted from the book?
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14th Jul 2016, 9:23 pm | #46 |
Rest in Peace
Join Date: Feb 2004
Location: Hexham, Northumberland, UK.
Posts: 2,234
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Re: "Illustrated Teach Yourself Radio" by David Gibson
I remember reading this book over and over again when I was a kid. I now have my own copy for nostalgia really. I have been building the superhet project with all the correct components on and off over the past couple of years. I never really had the money for all the coils etc when I was younger.
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