TK-II-STEREO Fully Integrated PS/2 Keyboard and Stereo Sound Board​

​Combining some of the most popular Pokey related upgrades for the Atari 8-Bit computer system into a single compact main board, with two choices of satellite connector interface boards.

It Piggy-Backs the existing Pokey chip providing an extra socket for a 2nd Pokey chip to be added thus creating the right channel sound output (4 extra voices), and integrates the Transkey-II PS/2 keyboard adapter to allow virtually any PS/2 keyboard or numeric keypad to be utilized in tandem with the stock Atari keyboard (supports two simultaneous PS/2 devices).

​And for all of the Ultimate 1Meg owners, you'll be glad to know that the stereo/mono U1MB electronic switching has already been built-in, ready to be controlled without any additional hardware required. ​
Un-Assembled Printed Circuit Boards are available from OSH Park, and can be ordered by using the green order buttons. Assembled versions are sometimes available on a limited basis from ​Bits of the Past website (contact owner).
TK-II-STEREO-MAIN_schema.pdf
File Size: 61 kb
File Type: pdf
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Internal Amp Hookup.pdf
File Size: 28 kb
File Type: pdf
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TK-II-STEREO_pcb.zip
File Size: 229 kb
File Type: zip
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TK-II-STEREO MAIN BOARD
Assembly Parts List

 R1,R2         470K
R3                4.7K
R4                1K
RN1,RN2   100K x 3 isolated resistor network
RN3            1K x 5 bussed resistor network
C1-C6         .1uf (axial)
C7,C8         10uf (radial)
D1,D2         1N914 (or 1N4148)
Q1-Q3         PN2222 (or PN2222A)
U1,U2          C012294 (POKEY)
U3                CD74HCT4066E
U4                PIC16F1847-I/P

Piggy-Back Header
(install prior to 40 pin sockets)
40 position Single Row Male Pin Break-Away Interconnect

XEGS Specific Vertical Headers
(Clearance for Cartridge Guide)
J1               MOLEX  10-89-7102 (Ribbon Cable)
J2               MOLEX  22-11-2082
J3               MOLEX  22-11-2042

Other XL/XE Systems Right Angle Headers
J1               MOLEX  90122-0765 (Ribbon Cable)
J2               MOLEX  22-12-2084
​J3               MOLEX  22-12-2044

Note: After assembly and before installing the Pokey chips, program the on-board PIC chip  via the J2 header using an ICSP programmer, prior to installation in the Atari (Get TK-II Firmware​).
Still supports dual PS/2 keyboards with Splitter Cord
(StarTech P/N: KYC1MF)
For more information on the TK-II-STEREO and connector interface boards --- including their development history and detailed installation photos go to the AtariAge Forum TK-II-STEREO Topic.
INTFC-S_schema.pdf
File Size: 15 kb
File Type: pdf
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INTFC_schema.pdf
File Size: 18 kb
File Type: pdf
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TK-II-STEREO INTERFACE
Assembly Parts List

MAIN-to-INTFC Header (mates w/Ribbon Cable)
Vertical Header          MOLEX  10-89-7102
Right Angle Header   MOLEX  90122-0765
Internal Audio Header (optional)
​Vertical Header          MOLEX  22-11-2052
​Right Angle Header   MOLEX  22-12-2052
3.5 mm External Audio Jack
              SwitchCraft   502-35RAPC4BVN4
PS/2 Ports
6-Pin Mini-Din             CUI  490-MD-60SM
4-40 Mounting Hardware 
​Right Angle Bracket   Keystone 621

Note: Use whichever style (vertical or right angle) header that best suits your installation requirements.

Either Molex or Dupont style connector housings and terminals can be used for board connections. Also it is permissible to substitute break-away pin headers for all of the Molex specified headers, if presently specified latching headers are not needed or desired. ​

Audio Output Specifications

The line level output from both sound channels was designed to meet the consumer audio -10 dBV standard  (0.316 V RMS / 0.447 V Peak).
It is a high impedance output not suitable for directly driving speaker loads, thereby requiring external amplification.

This standard was chosen because quite frankly the levels produced across the Atari 8-Bit series computers was inconsistent, ranging from quite low to very high. So not having an 'Atari' standard to go by, it was decided to use the consumer audio standard instead --- since this board will likely be plugged into present day consumer audio equipment (amplified speakers, Hi-Fi gear, LCD monitors).

Stereo Audio Connection

The TK-II-STEREO interface board's 3.5 mm stereo line output jack, although the same as used on many of the consumer headphones in use now days, can not directly drive this type of load. So some sort of amplification is required.

The audio input on many computer LCD monitors already makes use of the 3.5 mm stereo connector, but sometimes in the cheaper variety this is simply wired direct to internal speakers. So it is important to determine if the monitor's speakers are indeed amplified.