[This file contains information about building an Autofire Circuit ... and adding it to the Vectrex ... This circuit is already present in Atari configuration QuickShot & Quickshot2 joysticks. By building Jay Tilton's Digital to Analog adapter, this joystick and its Autofire circuit will work with the Vectrex ... This file was originally written by Marco Antonio of Lima, Peru and is updated by Rob Mitchell 11-OCT-99] You will need a 9-pin female and a 9-pin male connector, an LM 555 timer IC, two resistors (R1=R2=10K), two capacitors (C=100 nF, C1=0,42 nF), a two-position switch and some wire. Since you will need also an appropiate casing, I would recommend you to use a 9-pin null modem adapter (e.g., Radio Shack #26-264), which will provide you already with the casing, wiring and DB9 connectors. First, build the following autofire circuit in the smallest possible area (less than 0.5"x0.5"): ["Very Cramped!" --- Rob] +5V (Vectrex Pin 7 same as Atari Pin 7) | | /----------+ | | Z /--+ R1 Z .__|__|__. | | 8 4 | +----7 | | | 3--(Vectrex Pin 4 or Atari Pin 6) Z | LM 555 | R2 Z /-6 5----\ | | | | | +--+-2 | = C1 | |___1____| | | | | \---||---+---------/ C | | GND (Vectrex Pin 8 same as Atari pin 8) Frequency f=1.44/[(R1+2*R2)*C] or the inverse .... Time: T=0.694*(R1+2*R2)*C typical values: C1=0.42 nF R1=10 K R2=10 K C=100 nF (These are the values I selected.) If you are using the null modem adapter, skip this paragraph and continue with the next. If you aren't and are building the adapter with separate parts, then just connect each pin from the 9-pin female to the same pin on the male connector. Now you've just built what the adapter looks like on the inside. Now, if you are using the null modem adapter: just open the casing and accomodate the circuit inside. Make sure that all pins on the male are connected to the same pin # on the female (i.e., pin #1 to pin #1, pin #2 to pin #2, etc.) and not cross-connected. Now for both: Connect the +5V line to pin #7 (either on the male or the female connector, it's the same). Similarly, connect the GND line to pin #8. Cut the wire from pin #6 just in the middle. Now, proceed to make the following connections on the switch: / A / B o o o to | | | from male --/ | \-- fire | circuit | to female [Vectrex pin 4 or Atari pin 6] Now, make the appropiate holes in the casing for the switch. Fix the switch in place and close the casing. Now the portable autofire is ready for use. Just connect the portable autofire between the joystick port on the computer and the joystick's plug. With the switch in the A position, you will simply bypass the autofire circuit (autofire disconnected); when it is in the B position, the autofire is connected and the joystick's fire button is disabled. The advantage of this design is that you can connect the portable autofire to any joystick you want, without having to make any permanant modification to it. [Alternatively, you can add a switch that selects between Off, Pin 4 (Vectrex) and Pin 6 (Atari). That way you can use this circuit with other video game consoles. Or you can build it into a housing with Jay Tilton's Digital To Analog circuit Marco Antonio Checa Funcke Botoneros 270 Lima 33 Peru jtkirk@urp.edu.pe Craig Lisowski clisowsk@mcs.kent.edu Rob Mitchell acCIS on the fly!