Wednesday, April 29, 2015

Removing magnet wire enamel coating Insulation



3. Using acetylsalicylic acid found in aspirin drug:

[1] Put the wire (end) on top of the aspirin tablet. 
[2] Now using hot soldering iron, press against the wire (and tablet).
[3] Hold for 2-3 sec, then check for removal of coating.
[4] Repeat the process if necessary. 
[5] Clean the wire.
This can be combined with usage of smooth sandpaper (see 2).

Monday, March 23, 2015

Basic Soldering Lessons

Basic Soldering Lessons (1-9) ,youtube playlist:

https://www.youtube.com/playlist?list=PL926EC0F1F93C1837

(Produced by PACE, Inc.)

Tuesday, March 17, 2015

Saturday, November 8, 2014

AC Generator frequency as a function of RPM


w - angular velocity.
f - frequency (number of cycles per second, expressed in Hz).
P - number of poles (= N + S poles. ).
P/2 - number of pole pairs. Above generator example has two poles and one pole pair.
Ns - number of revolutions per second 
Nm - number of revolutions per minute
Nm=60*Ns.

w=2Pi*f = (P/2) * N * 2Pi * 1/sec

f=(P/2)*N/sec
f=(P/2)*Ns

f=(P/2)*Nm/60=P*N/120

f=P*Nm/120




Monday, November 3, 2014

Neodymium Magnet Physical Properties

(source: http://www.monroeengineering.com/NeodymiumMagnetPhysicalProperties.html)

Magnetic Characteristics
Material TypeResidual Flux Density
(Br)
Coercive Force
(Hc)
Intrinsic Coercive Force (Hci)Max.Energy Product
(BH)max
N3511.7-12.1 KGs>11.0 KOe>12 KOe33-35 MGOe
N3812.2-12.6 KGs>11.0 KOe>12 KOe36-38 MGOe
N4012.6-12.9 KGs>11.0 KOe>12 KOe38-40 MGOe
N4213.0-13.2 KGs>11.0 KOe>12 KOe40-42 MGOe
N4513.3-13.7 KGs>11.0 KOe>12 KOe43-45 MGOe
N4813.8-14.2 KGs>11.0 KOe>12 KOe45-48 MGOe
N5014.1-14.5 KGs>11.0 KOe>11 KOe48-50 MGOe
N5214.5-14.8 KGs>11.2 KOe>11 KOe49.5-52 MGOe
N35M11.7-12.1 KGs>11.4 KOe>14 KOe33-35 MGOe
N38M12.2-12.6 KGs>11.4 KOe>14 KOe36-38 MGOe
N40M12.6-12.9 KGs>11.4 KOe>14 KOe38-40 MGOe
N42M13.0-13.3 KGs>11.4 KOe>14 KOe40-42 MGOe
N45M13.3-13.7 KGs>11.4 KOe>14 KOe42-45 MGOe
N48M13.6-14.2 KGs>11.4 KOe>14 KOe45-48 MGOe
N50M14.1-14.5 KGs>11.4 KOe>14 KOe48-50 MGOe
N33H11.4-11.7 KGs>10.3 KOe>17 KOe31-33 MGOe
N35H11.7-12.1 KGs>10.8 KOe>17 KOe33-35 MGOe
N38H12.2-12.6 KGs>11.4 KOe>17 KOe36-38 MGOe
N40H12.6-12.9 KGs>11.4 KOe>17 KOe38-40 MGOe
N42H13.0-13.3 KGs>11.4 KOe>17 KOe40-42 MGOe
N45H13.3-13.7 KGs>11.4 KOe>17 KOe42-45 MGOe
N48H13.6-14.2 KGs>11.4 KOe>16 KOe45-48 MGOe
N30SH10.8-11.2 KGs>10.1 KOe>20 KOe28-30 MGOe
N33SH11.4-11.7 KGs>10.3 KOe>20 KOe31-33 MGOe
N35SH11.7-12.1 KGs>10.8 KOe>20 KOe33-35 MGOe
N38SH12.2-12.6 KGs>11.4 KOe>20 KOe36-38 MGOe
N40SH12.6-12.9 KGs>11.4 KOe>20 KOe38-40 MGOe
N42SH13.0-13.3 KGs>11.4 KOe>20 KOe40-42 MGOe
N45SH13.3-13.7 KGs>11.4 KOe>19 KOe43-45 MGOe
N28UH10.4-10.8 KGs>9.8 KOe>25 KOe26-28 MGOe
N30UH10.8-11.2 KGs>10.1 KOe>25 KOe28-30 MGOe
N33UH11.4-11.7 KGs>10.3 KOe>25 KOe31-33 MGOe
N35UH11.7-12.1 KGs>10.8 KOe>25 KOe33-35 MGOe
N38UH12.2-12.6 KGs>11.4 KOe>25 KOe36-38 MGOe
N40UH12.6-12.9 KGs>11.4 KOe>25 KOe38-40 MGOe
N28EH10.4-10.8 KGs>9.8 KOe>30 KOe26-28 MGOe
N30EH10.8-11.2 KGs>10.1 KOe>30 KOe28-30 MGOe
N33EH11.4-11.7 KGs>10.3 KOe>30 KOe31-33 MGOe
N35EH11.7-12.1 KGs>10.8 KOe>30 KOe33-35 MGOe
N38EH12.2-12.6 KGs>10.8 KOe>30 KOe36-38 MGOe
 
Thermal Characteristics
Neodymium Material TypeThermal Expansion Coeff.Maximum Operating TempCurie TempThermal Conductivity
%/¡ÆC¡ÆC (¡ÆF)¡ÆC (¡ÆF)kcal/m-h-¡ÆC
N-0.12176¡ÆF (80¡ÆC)590¡ÆF (310¡ÆC)7.7
NM-0.12212¡ÆF (100¡ÆC)644¡ÆF (340¡ÆC)7.7
NH-0.11248¡ÆF (120¡ÆC)644¡ÆF (340¡ÆC)7.7
NSH-0.10302¡ÆF (150¡ÆC)644¡ÆF (340¡ÆC)7.7
NUH-0.10356¡ÆF (180¡ÆC)662¡ÆF (350¡ÆC)7.7
NEH-0.10392¡ÆF (200¡ÆC)662¡ÆF (350¡ÆC)7.7
The Thermal Characteristics listed above are values commonly associated with each magnet's grade or material. Actual performance in your application may vary with other factors, including the shape of the magnet, the Permeance Coefficient or load line, and how it is used in a circuit.

Physical and Mechanical Characteristics
Density
7.4-7.5 g/cm3
Compression Strength
110 kg/mm2
Bending Strength
25 kg/mm2
Vickers Hardness (Hv)
560-600
Tensile Strength
7.5kg/mm2
Young's Modulus
1.7 x 104 kg/mm2
Recoil Permeability
1.05 ¥ìrec
Electrical Resistance (R)
160 ¥ì-ohm-cm
Heat Capacity350-500 J/(kg.¡ÆC)
Thermal Expansion Coefficient (0 to 100¡ÆC)
parallel to magnetization direction
5.2 x 10-6 /¡ÆC
Thermal Expansion Coefficient (0 to 100¡ÆC)
perpendicular to magnetization direction
-0.8 x 10-6 /¡ÆC


Plating Characteristics
Plating TypeOverall ThicknessSalt Spray TestPressure Cooker Test
NiCuNi (Nickel Copper Nickel)15-21 ¥ìm24 hours48 hours
NiCu + Black Nickel15-21 ¥ìm24 hours48 hours
NiCuNi + Epoxy20-28 ¥ìm48 hours72 hours
NiCuNi + Gold16-23 ¥ìm36 hours72 hours
NiCuNi + Silver16-23 ¥ìm24 hours48 hours
Zinc7-15 ¥ìm12 hours24 hours
Each individual layer of Nickel and Copper are 5-7 ¥ìm thick. The Gold and Silver plating layers are 1-2 ¥ìm thick.
Test results shown to allow comparison between plating options. Performance in your application under your specific test conditions may vary. Salt Spray testing conducted with a 5% NaCl solution, at 35¡ÆC. Pressure Cooker Test (PCT) conducted at 2 atm, 120¡ÆC at 100% RH.

Measurement Systems
Unitcgs SystemSI SystemEnglish System
Length (L)centimeter (cm)meter (m)inch (in)
Flux (©ª)MaxwellWeber (Wb)Maxwell
Flux Density (B)Gauss (G)Tesla (T)lines/in2
Magnetizing Force (H)Oersted (Oe)Ampere turns/m (At/m)Ampere turns/in (At/in)
Magnetomotive Force (mmf or F)Gilbert (Gb)Ampere turn (At)Ampere turn (At)

Conversion Between Systems
cgs System to SI system
1 Oe = 79.62 At/m
10,000 G = 1 T
1 Gb = 0.79577 At
1 Maxwell = 1 Line = 10-8 Wb
1 G = 0.155 lines/in2

Thursday, October 30, 2014

Maxima code based on equation 10 from "Calculation of the Magnetic Field Created by a Thick Coil"

/* 
####### Maxima package file (hthickcoil.mac) #######

This code is based on equation 10 from "Calculation of the Magnetic Field Created by a Thick Coil". DOI:10.1163/156939310791958653. 

Note: Equ. 10 has two errors. These are fixed in the code.
Errata:
1) In Hz(r,z) plus sign is replaced by minus sign.
2) In EtaZ term z[j] is replaced with z[k].
---------------------------------------------------------
Save this code in hthickcoil.mac file,then copy the file in one of the folders returned by 'file_search_maxima' command. Then execute load("hthickcoil.mac")$ 
For automatic load of Hring function one can put this line into maxima-init.mac file: setup_autoload("hthickcoil.mac",Hring)$ 

Usage: Hring(r,z,r1,r2,z1,z2,current).

r and z are cylindrical coordinates of point where you seek the H field.
r1 - inner radius, r2 - outer radius, z1 - lower position, z2 - upper position.

Output is in form of vektor: [HR, Hz, H].

For using built-in elliptic integrals in MAXIMA, see comments FIX1 and FIX2.
Maxima 5.31.2 version has issue with elliptic_ec function of negative argument.
*/

ellipticK(m):=block(

[qtemp1:0.0,qtemp2:0.0],qtemp1:float(qtemp1),
[qtemp1,qtemp2,qtemp2,qtemp2]:quad_qags(1/sqrt(1-m*sin(x)^2),x,0,%pi/2),
return (qtemp1)

)$

ellipticE(m):=block(

[qtemp1:0.0,qtemp2:0.0],qtemp1:float(qtemp1),
[qtemp1,qtemp2,qtemp2,qtemp2]:quad_qags(sqrt(1-m*sin(x)^2),x,0,%pi/2),
return (qtemp1)

)$

Hring(r,z,r_1,r_2,z_1,z_2,I):=
block
(
[Hr,Hz,H,j,theta,v,a,b,fi,kappa,d,c,f,eps:10^(-15),Eta_r,Eta_z,bracket1:0,bracket2:0,qtemp1,qtemp2],

r:float(r),z:float(z),r_1:float(r_1),r_2:float(r_2),z_1:float(z_1),z_2:float(z_2),I:float(I),j:float(j),
H:float(H),Hr:float(Hr),Hz:float(Hz),v:float(v),a:float(a),b:float(b),fi:float(fi),kappa:float(kappa),d:float(d),
c:float(c),f:float(f),bracket1:float(bracket1),bracket2:float(bracket2), qtemp1:float(qtemp1),

/* FIX1: uncomment line below if elliptic_kc/ec(nagative_argument) works. */
/* local (K,E), K(m) := elliptic_kc(m),E(m):=elliptic_ec(m), */

/* FIX2: if elliptic_kc/ec(nagative_argument) does not work use line below.Otherwise if you use FIX1 above then comment line below. */
local (K,E), K(m) := ellipticK(m),E(m):=ellipticE(m),

array(r,flonum,2),array(z,flonum,2),

r[1]:r_1,r[2]:r_2,z[1]:z_1,z[2]:z_2,

j:I/((r_2-r_1)*(z_2-z_1)),
v:r*sin(theta),

for i:1 thru 2 do (
for k:1 thru 2 do (

a: r^2+r[i]^2+(z-z[k])^2, 
b:2*r*r[i],
fi:(4/3)*sqrt(a-b)/(b+eps), 
kappa: 2*b/(b-a),
d:r[i]-r*cos(theta),
c:sqrt(a-b*cos(theta)),
f:z-z[k]+eps,

Eta_r:r*cos(theta)^2*log(d+c),
Eta_z:r*cos(theta)*log(f+c)+v*atan((d*f*csc(theta)/(r*c+eps)))-z[k]+v*atan(v/f),

[qtemp1,qtemp2,qtemp2,qtemp2]:( quad_qags(Eta_r,theta,0+eps,%pi-eps) + quad_qags(Eta_r,theta,%pi+eps,2*%pi-eps) ),
bracket1: bracket1 + ((-1)^(i+k))*(qtemp1+fi*((a+b)*K(kappa)-a*E(kappa))),

[qtemp1,qtemp2,qtemp2,qtemp2]:( quad_qags(Eta_z-f*log(d+c),theta,0+eps,%pi-eps)+quad_qags(Eta_z-f*log(d+c),theta,%pi+eps,2*%pi-eps) ),
bracket2:  bracket2 + ((-1)^(i+k))*qtemp1

) /* end_for_k */
), /* end_for_i */

Hr:ev((j/(4*%pi))*bracket1,numer), Hz:ev((j/(4*%pi))*bracket2,numer),

/* OUTPUT: [HR, Hz, H] */
return ([Hr,Hz,sqrt(Hr^2+Hz^2)])
)$


Monday, October 27, 2014

Double Factorial

          n(n-2)(n-4)...3*1  ; n>0 and odd
(n!!)= n(n-2)(n-4)...4*2   ; n>0 and even
          1              ; n=-1,0 ( -1!!=0!!=1)

(2n-1)!!=(2n)!/((2^n)*n!)

(2n)!!:=(2^n)n!

Tuesday, September 30, 2014

Running Firebird database server as application

0. Download firebird from: http://sourceforge.net/projects/firebird/files/
1. Unzip  Firebird-xxxxxxx-xxxxx.zip
2. Go to bin folder.
3. Execute fbserver with "-a" switch.
--------------------------------------------------
Example for windows:

Start cmd.exe and type:
cd Path_to_firebird\bin [enter]
fbserver.exe -a [enter]

(Use Flamerobin's "Register existing database..." option to connect to a .fdb file,
and then edit and view the contest of the same.
For username | password combo try: sysdba | masterkey)