Archive for the ‘Inductors’ Category:

2018-11-26 Two 6 uH RF Chokes

from FB group Building Transistor Radios 2018-11-26 https://archive.org/stream/ETIA1983/ETI%25201983-03%2520March_djvu.txt Two 6 uH RF chokes The photo shows two different RF chokes, each about 6.4 microhenrys. The one on the left is a ferrite bead, made by Fair-Rite, Cat. # 2643000801. These were about 12 cents apiece from Mouser.com. Yes, the wire passes through the small hole

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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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2017-06-02 I Built Another Oscillator For AM BCB

I pulled a pill bottle out of my junk box, it had a single layer of solid enameled wire wound on it, and it measured 85 microhenrys.  So I added the transistor, resistors and the capacitors to get it to oscillate at the low end of the AM BCB, around 540 kHz. The schem is

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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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2016-05-28 The Five For A Dollar Toroid Core Is Back

A few years ago the Joule Thief fans and others built many projects with a very popular toroid core that was sold from Electronic Goldmine, a surplus electronics company, for the affordable price of five for a dollar.  Eventually the supply was all sold and it was no longer available.  The stock # was G6683.

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2016-05-16 Tape Wound Toroid Core From Surplus Sales

Long ago I built DC-DC converters using a toroid made with tape wound core. The cores were about 2 inches O.D. and we used regular 12 AWG solid insulated house wire for the primary windings. Even so, these cores vibrated a lot at several hundred Hz, making a screeching noise. I saw some very small

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2016-04-18 Coil For FM Microphone Bug Transmitter

I’ve built an FM microphone bug or transmitter before, but it’s been a very long time since I wound coils for one.  Long ago I would wind too many turns on the coil and try it out.  The usual outcome was the bug would be transmitting somewhere in the low TV channels 5 or 6,

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2014-11-30 All Electronics TOR-74 And FB-102

I bought some cat# TOR-74 from All Electronics for 4 for $1.00.  They say these toroid cores are Magnetics ZF410057C, but Google didn’t turn up any data on them.  They are coated Grey, and are 9.5mm O.D., 4.5mm I.D., and 5.0mm high, or .375 inch O.D., .178 inch I.D., and .197 inch high. This is

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