Transcript Toroids - M1HOG

Toroids
An Introduction
By Nicolas - M1HOG
What is Toroid?
• Doughnut shaped object
whose surface is a torus.
Its annular shape is
generated by revolving a
circle around an axis
external to the circle.
What is a Toroidal Inductor?
• A coil of insulated wire,
usually wound round a
core of iron or similar
metal in a doughtnut
shape.
Why use Toroids?
• High performance
• They can be mounted closely together
• Can be made in a wide range of values and
characteristics
• Simple to make
• Q – High Quality factor (or Q)
• Economic!
Example Uses
• RF Chokes - An inductor designed to have a high
impedance to RF current and low impedance to DC
current.
• Transformer / impedance matching
• Variable-frequency oscillator (VFO) - The frequency is
set by a tuned circuit using capacitors and inductors. The
frequency can be changed by adjusting the components
in the tuned circuit.
• Band pass filter - Small capacitor used to tune
• Mixers - Used in transformers for Diode Ring Mixers.
Ready built and homebrew.
• Many Others
Toroid Specification
Toroid T37-2
length
in inches
OD = 0.375 in. / 9.53
mm
ID = 0.205 in. / 5.21
mm
Ht = 0.128 in. / 3.25
mm
# of
Turns
Inductance
in uH
6
.11
5.0"
8
.20
6.0"
= 2.31 cm
A = 0.064 cm2
V = 0.147 cm3
10
.31
7.0"
12
.44
8.0"
OD - +/- 0.015 in.
ID - +/- 0.015 in.
Ht - +/- 0.02 in.
14
.60
9.0"
16
.78
10.0"
AL
uH = (AL * Turns2) / 1000
3.0
18
1.0
11.0"
Basic Iron Powder
Carbonyl SF
20
1.2
12.0"
Material Permeability (µ°)
8.5
22
1.5
13.0"
24
1.8
14.0"
26
2.1
15.0"
28
2.4
16.0"
30
2.7
17.0"
Physical Dimensions
Magnetic Dimensions
Dimensional Tolerance
Temperature Stability (ppm /°C)
* averaged from -55C° to +125C
Magnetic Tolerance
* tested with evenly-spaced windings
35
+/- 5 %
Toroidal Color Code
Yellow/Clear
Resonant Circuit Frequency
Range
3MHz - 40MHz
* range is given to optimize Q and core
loss
includes
1 inch tails
Toroid Table
material #1 u=20 0.5-5 MHz
material #2 u=10 2-30 MHz
material #6 u=8.5 10-50 MHz
material #10 u=6 30-100 MHz
material #61 u=125 0.2-15 MHz
material #43 u=850
Size->
T37
T44
T50
T68
AL->
40 30 55.3 420
52 42
100 49 40 31 68 523
57 47
Turns
Inductance in uH, and length in inches
6
.14 .11 1.99 15.1 5.00"
.19 .15
.18 .14 2.45 18.8 5.75"
.21 .17 6.50"
8
.26 .19 3.54 26.9 6.00"
.33 .27
.31 .26 4.35 33.5 7.00"
.37 .30 8.00"
10
.40 .30 5.53 42.0 7.00"
.52 .42
.49 .40 6.80 52.3 8.25"
.57 .47 9.50"
12
.58 .43 7.96 60.5 8.00"
.75 .60
.71 .58 9.79 75.3 9.50"
.82 .68 11.00"
14
.78 .59 10.8 82.3 9.00"
1.0 .82
.96 .78 13.3 102 10.75"
1.1 .92 12.50"
Toroids In Circuits
L3 Single winding
Toroids In Circuits
T3 Bifilar winding
Construction - Before we start
• Counting turns, each pass through the core counts as
one turn
• Coverage 85%
• Neatness is not generally critical. But get a tidy result
and it makes any subsequent checking easier!
• Wind in the same direction (sometimes direction matters)
if only to get the coloured sides all facing the same way!
• US vs UK wire sizes – Conversion tables
• Ideally use wire with a heat strippable insulator
Construction – Tools
•
•
•
•
•
•
•
Standard workshop tools
Pliers - fine
Soldering iron
Cutters
Vice / blu-tack etc to hold toroid while tinning leads etc
Magnifier - Ideally illuminated
Storage - If you are working on a few toroids; to avoid
having to recount turns – was that one 32 or 38 and
which core was it wound
Construction - Winding
• Remember every pass
through the core counts as a
turn
• Over wind by 3 turns and
remove these when complete
• Pull each turn against the core
to ensure it is tight.
• Thread using a Blunt Darning
needle. Not tried this
technique myself but some
recommend it
• Don’t rush
Construction – Bifilar Winding
• Twisting the wire
• 6 to 8 turns per inch
• Different colour wires can
be used
Construction – Preparing the
leads
• Ideally use wire with a heat strippable insulator
• Can be stripped with sand paper or a craft knife
• Strip them back close to the toroid
Construction - Testing and
Measuring
• The Atlas LCR
automatically identifies and
analyses almost any
passive component
(Inductor, Capacitor or
Resistor).
Inductance from 1uH to
10H, Capacitance from 1pF
to 10,000uF and
Resistance from 1ohm to
2Mohm. Atlas Component
Analyser
Construction - Installation
• Pliers to pull the leads through the PCB holes tightly,
solder then reheat the joint pulling the wire through to get
it tight.
• Triple check the wiring before cutting of surplus leads.
Can be difficult to reinstall with trimmed leads!
Construction - Stability
Construction – Don’t Rush
• Take a break, it does not
have to be a marathon!
• The 30 toroids for this
band pass filter board
were completed over
several lunchtimes, and
bottles of beer.
Suppliers
•
•
•
•
G-QRP - http://www.gqrp.com/
Jab - http://www.gqrp.com/
Sycom - http://www.sycomcomp.co.uk/
Toroid Kits - http://qrpkits.com/
(Favorable rate exchange rate!)
Credits
SADARS
Elecraft
GM1SXX
GW4ALG
G-QRP Club
Wikipedia
W8DIZ
Goose Island IPA
And Many Others!
Thank you !
This presentation is
available at
www.M1HOG.com