City #32 04 октября 1999

Железо

Iron - Scheme of the light pen for ZX Spectrum.

   *********** ************ PLANET SHELEZYAKA



                  Light pen
(C) V. Kazakov


  Present to you the diagram light pen,
taken me from a book published by "Inforkomom in
1994 "Personal Computer <ZX-SPECTRUM>. Peripherals with their 
own hands." 

  For the manufacture of light pen you ponadabyatsya
K155LP8 chip, 2 resistors 10 k, 2 resistor
470 kOhm, 1000 pF capacitor and transistor in KT3102E
metal casing.

  Thus, the circuit of the light pen:

+5 V

                        o o o

         DD1.1
IORQ / 2 R1 R2 R3 * R4

       1 LP8 3 10k 10k 470k 470k

      1

       oEZ



           DD1.2
RD / 5

         1 LP8 6

        4 o

         oEZ


A6 9

            1 LP8 8

          10 o

            oEZ C1

                       DD1.3 1000

D1 o o
K155LP8 12

                  1 LP8 11

               1913 b_ / k

                 oEZ VT1 e

                                 KT3102E

                   DD1.4
D0



  Itself shemka collected and connected to a computer is 
elementary, so these processes, I shall not dwell, and more 
details about the manufacture of the "pen". 

  For him, used the body from the pen, pens
etc., of such size that inside the near
inlet could accommodate a light sensitive element, as which can 
be used, for example, in our scheme, the transistor VT1 KT3102E 
to cut down the lid. Pen connected to the circuit with a 
flexible wire length of 1 - 1,5 m.


  To test the efficiency of the light pen and
adjust its sensitivity can recommend a small program in BASIC:


  10 PRINT BRIGHT 1; AT 10,16; ""

  20 IF SIN ((PI / 2) * IN63) = 0 THEN BEEP .05, RND

     * 50: BORDER RND * 7

  30 GO TO 20


  After starting the program in the middle of the screen will 
show the familiarity of high brightness. Put a light pen in 
front of a bright familiarity. When properly work schemes you 
hear the "music", accompanied by changing the color border. 
Sensitivity should be adjusted so that the "music" stopped at 
removing the "feather" from the screen, ie, no false positives. 
Sensitivity is adjustable by selecting resistor R3 in the range 
0.3 - 3.3 MW. Also, it depends strongly on h21e transistor.


  To complete the work with the light pen is a special program 
- graphics editor LP48K, you can order our editorial staff.


  Other "branded" software that uses a light pen, I have not 
yet met ...