OpenBCM V1.08 (Linux)

Packet Radio Mailbox

PI8DRE

[Drenthe]

 Login: GUEST





  
G8MNY  > TECHNI   22.11.21 09:20l 128 Lines 5077 Bytes #999 (0) @ WW
BID : 53758_GB7CIP
Read: GUEST
Subj: Odd Resistance Finder
Path: PI8DRE<PI8CDR<DB0RES<ON0AR<GB7CIP
Sent: 211122/0806Z @:GB7CIP.#32.GBR.EURO #:53758 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

By G8MNY                                       (Updated Nov 07)
Resistors normally come in 2 ranges, E12 has 12 resistors evenly spaced per
decade about 20% to the adjacent value, & E24 has 24 & includes the E12 series
giving value at about 10% apart. As tolerances improve there are also E24 &
E48 values available!

E12  1.0   1.2   1.5   1.8   2.2   2.7   3.3   3.9   4.7   5.6   6.8   8.2
E24   + 1.1 + 1.3 + 1.6 + 2.0 + 2.4 + 3.0 + 3.6 + 4.3 + 5.1 + 6.2 + 7.5 + 9.1

Here is a useful list of 128 values obtained with two E12 resistors.

Multiply or Divide by 10s for the range needed.

   Wanted    How                 Wanted    How
E12 1000                          3400   6k8//6k8, 1k2+2k2
    1020   1k2//6k8               3590   5k6//10k
    1031   1k5//3k3           E24 3600   1k8+1k8
    1047   1k2//8k2               3700   1k+2k7, 1k5+2k2
    1071   1k2//10k               3717   6k8//8k2
    1080   1k8//2k7           E12 3900   1k2+2k7
    1083   1k5//3k9               4000   1k8+2k2
E24 1100   2k2//2k2, 1k+100       4048   6k8//10k
    1137   1k5//4k7               4100   8k2//8k2
    1165   1k8//3k3               4200   1k5+2k7
    1182   1k5//5k6           E24 4300   1k+3k3
E12 1200                          4400   2k2+2k2
    1212   2k2//2k7               4500   1k2+3k3
    1229   1k5//6k8               4505   8k2//10k
    1232   1k8//3k3           E12 4700
    1269   1k5//8k2               4800   1k6+3k3
E24 1300                          4900   1k+3k9, 2k2+2k7
    1301   1k8//4k7               5000   10k//10k
    1304   1k5//10k           E24 5100   1k2+3k9, 1k8+3k3
    1320   2k2//3k3               5400   1k5+3k9, 2k7+2k7
    1350   2k7//2k7               5455   10k//12k
    1362   1k8//5k6               5500   2k2+3k3
    1406   2k2//3k9           E12 5600
    1423   1k8//6k8               5700   1k+4k7, 1k8+3k9
    1476   1k8//8k2               5900   1k2+4k7
    1485   2k7//3k3               6000   12k//12k, 10k//15k, 2k7+3k
    1497   2k2//4k7               6100   2k2+3k9
E12 1500                      E24 6200   1k5+4k7
    1525   1k8//10k               6429   10k//18k
    1580   2k2//5k6               6500   1k8+4k7
    1596   2k7//3k9               6600   1k+5k6, 2k7+3k9, 3k3+3k3
E24 1600                          6667   12k//15k
    1650   3k3//3k3           E12 6800   1k2+5k6
    1662   2k2//6k8               6875   10k//22k
    1715   2k7//4k7               6900   2k2+4k7
    1735   2k2//8k2               7100   1k5+5k6
    1788   3k3//3k9               7200   18k//12k, 3k3+3k9
E12 1800                          7297   10k//27k
    1803   2k2//10k               7400   1k8+5k6, 2k7+4k7
    1822   2k7//5k6           E24 7500   15k//15k
    1933   2k7//6k8               7674   10k//33k
    1939   3k3//4k7               7765   12k//22k
    1950   3k9//3k9               7800   1k+6k8, 2k2+5k6, 3k9+3k9
E24 2000   1k+1k                  7959   10k//39k
    2031   2k7//8k2               8000   1k2+6k8, 3k3+4k7
    2071   3k3//5k6               8182   15k//18k
    2126   2k7//10k           E12 8200
    2131   3k9//4k7               8246   10k//47k
E12 2200   1k+1k2                 8300   1k5+6k8, 2k7+5k6
    2222   3k3//6k8               8308   12k//27k
    2299   3k9//5k6               8485   10k//56k
    2350   4k7//4k7               8600   1k8+5k6, 3k9+4k7
    2353   3k3//8k2               8718   10k//68k
E24 2400   2k2+2k2                8800   12k//33k
    2479   3k9//6k8               8900   3k3+5k6
    2481   3k3//10k               8913   10k//82k
    2500   1k+1k5                 8919   15k//22k
    2555   4k7//5k6               9000   18k//18k
E12 2700   1k2+1k5            E24 9100
    2779   4k7//6k8               9091   10k//100k
    2800   5k6//5k6, 1k+1k8       9176   12k//39k
    2806   3k9//10k               9200   1k+8k2
    2988   4k7//8k2               9400   1k2+8k2, 4k7+4k7
E24 3000   1k2+1k8, 1k5+1k5       9500   2k7+6k8, 3k9+5k6
    3071   5k6//6k8               9559   12k//47k
    3197   4k7//10k               9643   15k//27k
    3200   1k+2k2                 9700   1k5+8k2
E12 3300   1k5+1k8                9882   12k//56k
    3328   5k6//8k2               9900   18k//22k

  // = in parallel,   + = in series

Series combinations are better for high voltage.
Similar values spread the power dissipation more evenly.

So now you can replace that experimental preset value with 2 fixed value Rs.
------------------------------------------------------------------------------
From Jim VK7JH

     R1 x R2
 R = -------
     R1 + R2

The formular can be written as:

 1     1     1
--- = --- + ---
 R     R1    R2

Re-aranging gives:

 1     1     1
--- = --- - ---
 R2    R     R1

Putting it in the form that you started with:

         R x R1
R2  =  ----------
         R1 - R

R is the value you want & R1 is something higher in value.

There are tables that give the combination of prefered values to
save the calculations. I think I saw a TECH buletin....


Why Don't U send an interesting bul?

73 De John, G8MNY @ GB7CIP


Read previous mail | Read next mail


 05.12.2021 22:49:43lGo back Go up