Archive for the ‘Toroids and Cores’ Category:


I found that 100 uH was a good all around value for these solar garden light circuits. But at the time I made these around 2009 the 5252 4 legged chip was uncommon and almost all the garden lights used 2 discrete transistors. I don’t know why they started using the 4 legged 5252 –

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2018-09-07 Q of an Inductor

from FB group Building Transistor Radios, 2018-09-07 Tom Miller Say a capacitor or inductor has a Q of 100. The losses are about 1/100 of the energy in the component. In a tuned circuit the capacitor Q is usually much higher than this – it has lower losses, so the more important is the Q

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2018-04-22 Ferrite Loopstick Basics

From FB group Building Transistor Radios Then there is the loopstick. It is deliberately made long and thin to capture the RF magnetic fields. The frequencies that loopsticks are better at capturing are those that require long antennas that would be impractical. So the AM broadcast band is where loopsticks do their best. The loopstick’s

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2017-11-19 Royal 510 PCB hairline crack 

For FB group Vintage Transistor Radios  Speaking of fuzzy garbled audio…  I won another auction for a Zenith “Royal 510” which I’d never heard of.  It turned out to be a Royal 250.  The seller got no bids at all, so with less than a minute left I bid the minimum ten dollars. I got

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2016-09-05 Ferrite Cores At Radio Frequencies

I have always thought that using ferrite toroid cores for radio projects at HFs and above was not necessary, because all of the RF circuit parts lists call for low permeability powdered iron cores. I’ve never given it much thought; about the only thing that crossed my mind was that the powdered iron cores may

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2016-06-05 Toroid Cores 10 mm .4 Inch Green

I was on eBay and saw some small green ferrite toroid cores, ten for 99 cents including shipping.  I figured that since I had bought some larger green cores a few weeks ago and liked them, I couldn’t go wrong buying these since they were less than ten cents apiece. They were sent from an

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2016-06-04 Crystal Radio Coils, Crystal Diodes

I was reading some of Geo John’s projects and came across a crystal radio set that he built using two tuned coils. A crystal radio set refers to the type of detector used, which was once a galena crystal and a ‘catwhisker’ to find a sensitive spot on the crystal. Nowadays, that is no longer

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