Variable Capacitors
Crystal Radio Inductors
- Torroid Winding
- Other Coils
Joule Thief Transformers
Diodes
Transistors

Electronic Components On-hand

These are some of the components available for testing.

Variable Capacitors

			Typical
Type	Nominal (pF)	Drive	Min	Max
Air	365	Direct
Air	381	8:1 Planetary	14	400
Air	320/380	6:1 Vernier
Air	320/14.7/380/14.7	3:1 Vernier	12/9/12/9	345/25/405/25
Air	480/505	6:1 Vernier	8/8	520/500
Plastic	60/160	Direct
Plastic	266/266	Direct
Piston, Hi-Q	1-25	Direct
Compression	6-50	Direct

Crystal Radio Inductors

Inductance needed for capacitor values.1)

C=381+20=401 pF, f=520 kHz = 3.267e6 rad/sec $omega =1/{sqrt{L C}} right L=1/{C omega^2}=1/{401*10^{-12} *3.267^2*10^{12}}=234 mu H$

Cmax	Cstray	L(520 kHz)	C(1710 kHz)
(pF)	(pF)	(µH)	(pF)
365	20	243	36
410	20	218	40
380/320	20/20	234/276	40/20

Torroid Winding

Iron Powder Toroidal Cores (For Resonant Circuits)

Core		Winding				Inductance (µH)
	A_L	Done	Length	Layers	Turns*	Calculated	Measured
2xFT23-43	2×158±20%		15”?	2	28	248
f8FT23-43	2×158±20%		23”?	2	2×28	248
FT37-43	350±20%		17”	1	26	237
FT50-43	440±20%		19”	1	23	233
FT50-61	69±20%		42”	1	58	232
T130-2	11±20%		214”	1	145	231
T200-2	12±20%		266”	1	138	229

Giant Ferrite Bead Information

It takes about 20’ of 30 gage wire to wind a giant bead fully (estimated 92 turns) for about 20 mH (measured 19.4 mH). [2007-11-13]
About 2.43”/turn
$uH={A_L *Turns^2}/1000 right A_L={1000 L}/{Turns^2}={1000*113}/{7^2}$ =A_L≈2300

Big Ferrite Torus

$uH={A_L *Turns^2}/1000 right A_L={1000 L}/{Turns^2}={1000*62}/{11^2}$ =A_L≈512
$Turns=sqrt{{1000 L}/{A_L}} = sqrt{{1000*184}/512}approx$ 19 turns

Other Coils

The cigar box radio coil is about 23 turns of #26 (or #24) around a 5½” x 9” x 2½” box, around 80’ of wire.
6’ of 16-conductor ribbon cable makes a quick and dirty coil.

Joule Thief Transformers

Coils to Wind Twice with 30-gauge Wire

Core		Winding				Inductance (µH)
	A_L	Done	Length	Layers	Turns*	Calculated	Measured
FT23-43	158±20%	✔	10”	1	14	31	46
FT23-43	158±20%	✔		2	28	124	241
2xFT23-43	2×158±20%	✔		1	14	62	93
2xFT23-43	2×158±20%			2	28	248
f8FT23-43	2×158±20%	✔		1	2×14	62	93
f8FT23-43	2×158±20%			2	2×28	248
FT37-43	350±20%	✔	30”	1	20	140	126
FT37-43	350±20%		60”	2	42	617
FT37-61	55±20%	✔	31”	1	21	24	18
FT37-61	55±20%		62”	2	42	97
T37-2	4±5%	✔	31”	1	25	2.5	UR
T37-2	4±5%		62”	2	50	10
T37-6	3±5%	✔	31”	1	25	1.9	UR
T37-6	3±5%		62”	2	50	7.5
FT50-43	440±20%		50”	1	36	570
FT50-43	440±20%	✘	112”	2	72	2281	–
FT50-43	440±20%	✔	40”	1	28	345	367
FT50-43	440±20%	✔	36”	1	24	253	277
FT50-43	440±20%	✔	30”	1	20	176	190
FT50-61	69±20%	✔	56”	1	36	89	69
FT50-61	69±20%		112”	2	72	358
T50-26			56”	1	36	41
T50-26		✔	20”	1	21	14	11
T50-1	10±10%	✔	56”	1	36	13	8
T50-1	10±10%	✔	112”	>2	72	51	49
T50-2	4.9±5%		56”	1	36	6.4
T50-2	4.9±5%		112”	2	72	21
T50-6	4±5%		56”	1	36	5.2
T50-6	4±5%		112”	2	72	16

μH = (AL*Turns²)/1000
* Italics indicate a full winding.
✘ Not tested. The inductance is not appropriate for a joule thief.
✔ Tested in a joule thief circuit.
2x indicates two cores stacked and wound together.
f8 indicates a figure-eight winding of two cores side-by-side.
UR indicates inductance too low for my cheap multimeter to register.

	Color	u	Frequncy (MHz)
-43	Shiny Black	850	(0.5-30)
-61	Dull Dark Gray	125	0.2-15
-26	Yellow/White		–
-3	Gray		0.050-0.5
-1	Blue/Clear	20	0.5-5, 0.15-3
-2	Red/Clear	10	2-30, 0.25-10
-6	Yellow/Clear	8.5	10-50, 3-40

Data adapted from Maximum Turns, Toroid Windings for QRP projects, Mike Czuhajewski’s Toroid Charts, and Ian Purdie VK2TIP’s "Toroids" page.

Diodes

Part	Type	I_F(AV)	V_R	Rated V_F*	V_F@20mA,25ºC	Measured V_F†	C_T
		(A)	(V)	(V)	(V)	(V)	(pF)
1N5817	Schottky	1	20	0.45	0.23	0.165	125
1N5819	Schottky	1	40	0.45	0.23	0.205	110
21DQ06	Schottky	2	60	0.55	<0.32	0.298	120
MBR1100	Schottky	1	100	0.68	<0.42	0.299	35
BAT46	Schottky	0.15	100	0.80	0.51	0.254	6-10
1N34A?	Schottky					0.307
1N34A	Ge		65	>1.00	>1.00		0.8
1N60	Ge
1N60-odd	Ge
1N60P	Schottky	0.5	45	0.84	0.34	0.279	2-6
1N198	Ge	0.5	100	1.00	>1.00	0.278	low‡
1N277
1N277B
“Unknown”	Ge	–		–	–	0.364	–
“Mystery”	Ge	–		–	–	0.293	–

*Usually @I_F(AV), T_J=125ºC
†Measured with cheap multimeter, probably at about 1.25 mA
‡Observed to be similar to 1N34A.

Transistors

Part	Polarity	Material	V_FBE	V	I_C,max	h_FE	f_T	Use Coil	Package
			V	V	mA		MHz	µH
ГТ402Б	PNP	Ge	0.201	25	500	60-150	1
ГТ404Б	NPN	Ge	0.168	25	500	60-150	1
гт4125	PNP	Ge	0.260	24	500	≥70	2	300-600
2N1017	PNP	Ge	0.226	?10	400	20-30	20	20-400
1T321E	PNP	Ge	0.128	40	200	80-200	60
Кт321Б	PNP	Si	0.646	50	200	40-120	60
SFT131	PNP	Ge	0.166	24	500	≥70	2		TO-5var
MP26A	PNP	Ge	0.212	70	400	20-40	0.2		TO-9

Russian transistor information from the datasheet, vendor information, and “Help parameters for the transistors of low power” and “...of average capacity“.
Russian package illustrations from The Directory on Bipolar Transistors.

“...the emitter-base junction possesses a slightly greater forward voltage drop than the collector-base junction.”–Lessons In Electric Circuits -- Volume III, Chapter 4

1) $L_{mu H} = 25330.3/{C_{pF} {f_{MHz}}^2}$

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