Retro Review: Retro Review Radio Shack EC-480

Retro Review:   Retro Review Radio Shack EC-480

Quick Facts

Model:  EC-480

Company:  Radio Shack

Years:  1976-1977

Type:  Scientific 

Batteries: 2 x AA, separate AC power 

Operating Modes:  Chain

Number of Registers: 1

Display:  8 digits, 1 left character for shift and error indicator

The EC-480 comes to have a brown, thin faux-leather cover.  

Pocket Sized Scientific Calculator

The EC-480 is a no-frills, lightweight, scientific calculator: just the basics.   Most likely, this would be an on today's smartphones.  The keys are plastic and thankfully the keys are responsive.   You can hear a click when the keys are pressed.  

Every of the 20 keys has a shifted function.  A smart move is the put the ON-OFF switch instead of making it a key.  

The keyboard:

C/CE; 1/X

F; cf  (Shift; Clear Shift)

EEX; conv

÷; arc  (for arcsin, arccos, arctan)

7; sin

8; cos

9; tan

×; sto 

4; e^x

5; 10^x

6; y^x

-; rcl

1; ln

2; log

3; √

+; m+

+/-; x^2

0; π

.;  (

=; )

The angle measurement used is degrees.

The conv function toggles the screen.  When a number is big or small enough to show a exponent, the conv functions shows the mantissa.  For example:

5.5.638 E 11 

× 1.2365 E 10 

= 6.8796 E 21

(conv) 6.8796387   (6.8796387 * 10^21)

(conv) 6.8796 E 21

The one thing I do not like about the EC-480 is that sometimes the 10^x function is sometimes inaccurate due to rounding error.  For example:

10^3 returns 1000

10^4 returns 10000

10^5 returns 99999.999

10^6 returns 999999.99

10^7 returns 10000000

Try 2^x * 5^x instead.  (Possible keystrokes:  2 y^x x = sto 5 y^x x * rcl =)

No Order of Operations

The EC-480 does not follow the order of operations, instead of the chain operating system.  This may be a turn off for some people.  Just to illustrate this:

4 + 5 × 6 returns 54

4 + ( 5 × 6 ) returns 34

5 × 6 + 4 returns 34

Green Display

The display has 9 characters.  The right 8 contain numbers, with the left as an indicator.   

#.#.#.#.#.#.#.#.#.

The first decimal point indicator appears when you press the blue shift key.  

The left character is a negative sign with nothing else is when the calculator is sleeping.  I like this feature to save battery.  

Source

Flow Simulation Ltd.  "Radio Shack EC-480"  calculator.org 2022.  https://www.calculator.org/calculators/Radio_Shack_EC-480.html   Retrieved June 5, 2022

Eddie

All original content copyright, © 2011-2022.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author. 

Applications: Sharp EL-5150

Applications:  Sharp EL-5150 

Note:  spaces included for readability

Fan Laws

AER Equation:

1; f(BCDI) = B * ( C ÷ D ) Y^x ( 1 ÷ I  )

Variables:

Calculate CPM_new

B = CPM_old

1st Fan Law:

I = 1

C = RPM_new

D = RPM_old

2nd Fan Law:

I = 2

C = SP_new

D = SP_old

3rd Fan Law:

I = 3

C = BHP_new

D = BHP_old

Example 1:

Fan Law 2:

CPM_old = B = 4000 CPM

SP_new = C = 48 

SP_old = D = 36

I = 2

Result:  4618.802153

Example 2:

Fan Law 3:

CPM_old = B = 3500 CPM

BHP_new = C = 59

BHP_old = D = 52

I = 3

Result:  3650.488072

Ideal Shockley Diode Equation

I = I0 * e^((VD/(n* VT) - 1)

where VT = K * T/q

I = diode current (amps)

I0 = saturation current (amps)

VT = thermal voltage (V) - see notes below

VD = voltage across the diode (V)

n = ideality factor, in ideal situations, n = 1

Notes:  

*  The equation below assumes the ideal diode, n = 1

*  The equation uses a ratio of scientific constants:  k/q 

*  k = Boltzmann's Constant = 1.380649 * 10^-23 J/K

*  q = Charge of an Electron = 1.602176634 * 10^-19 C  (on some calculators, like the Casio fx-991EX, this constant is labeled e)

*  k/q = 8.617332385 * 10^-5 J/(K*C) = 8.617332385 * 10^-5 V/K  (volts/degrees Kelvin)

AER Equation:

1; f(IDE) = 8.617332385E-5 × E STO A, I ×(e(D ÷ A) - 1)

Calculate VT (stored in A), the I 

I = I0

D = VD

E = temperature in Kelvin

Example 1:

I = 4E-6 A 

D = 0.08 V

E = 280 K

Results:

A = 0.024128531, (I) 0.00001061

 

Example 2:

I = 4E-6 A 

D = 0.06 V

E = 300 K

Results:

A = 0.025852000, (I) 0.00003674

Dot and Cross Product of Two 3D Vectors

For the two vectors [A, B ,C] and [D, E, F]:

AER Equations:

1; f(ABCDEF) = A × D + B × E + C × F ◣

2; B × F - C × E, C × D - A × F, A × E - B × D

Example 1:

[ A, B, C ] and [ D, E, F]

[ 4.5, -2.5, -8 ] and [ 1.6, 3.9, 6 ]

Dot Product:  -50.55

Cross Product:  [ 16.2, -39.8, 21.55 ]

Example 2:

[ A, B, C ] and [ D, E, F]

[ 4, 3, 2 ] and [ 2, 7, 0 ]

Dot Product:  29

Cross Product:  [ -14, 4, 22 ]

Law of Cosines

Sides with lengths A, B, C with D as the angle opposite of A.  Equation 1 finds the length of side A, while Equation 2 finds the angle D.

AER Equations:

1; f(BCD) = √(B^2 + C^2 - 2 × B × C × COS D) STO A ◣

2; f(ABC) = cos^-1 ((B^2 + C^2 - A^2) ÷ (2 × B × C)) STO D

Example 1 - find A:

Degree Mode Set

Input:  B = 4.5, C = 3.7, D = 30°

Run 1:

Result:  2.258617731

Example 2 - find D:

Degree Mode Set

Input:  A = 40, B = 56, C = 38

Run 2:

Result:  45.5579132°

Note:  Due to the incredible amount of spam comments that get sent on this blog, which I moderate so the readers don't see them, I have decided to turn comments off.  I will review whether to turn comments back on at a later time.  My apologizes to those who leave legitimate comments.  

Eddie 

All original content copyright, © 2011-2022.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.