C64 50Hz TOD Generator
author: mbarszcz
2 layer board of 2.05 x 1.49 inches (52.0 x 37.7 mm)
Uploaded:
August 24, 2018
Shared:
August 24, 2018
Total Price:
$15.20
50Hz Time of Day CIA pulse generator for running a PAL C64 on a 60Hz power supply. Based on this schematic, but with bypass capacitors on all the chips: http://pasilassila.blogspot.com/2016/08/5060hz-tod-clock.html.
Attach 5v and ground from anywhere on the motherboard, and the 50Hz output goes either to the input pins of the CIAs (pin 19) or to the schmitt trigger (U23 pin 1). Be sure to lift the appropriate traces supplying the 60Hz pulse from the AC input.
BOM:
(3) 100nF Decoupling Capacitors
(1) SG-531P 4.096 MHz Oscillator
(1) 74HCT4060 14 Stage Counter (4.096 MHz / 8192 = 500Hz)
(1) 74HC4017 Decade Counter (500Hz / 10 = 50Hz)
(2) 0.1" pin headers for test points (if desired)
Note, a 60Hz output can be generated instead by substituting the 4.096 MHz Oscillator for a 4.9152Mhz Oscillator (also SG-531P).
Schematic:
50Hz Time of Day CIA pulse generator for running a PAL C64 on a 60Hz power supply. Based on this schematic, but with bypass capacitors on all the chips: http://pasilassila.blogspot.com/2016/08/5060hz-tod-clock.html.
Attach 5v and ground from anywhere on the motherboard, and the 50Hz output goes either to the input pins of the CIAs (pin 19) or to the schmitt trigger (U23 pin 1). Be sure to lift the appropriate traces supplying the 60Hz pulse from the AC input.
BOM:
(3) 100nF Decoupling Capacitors
(1) SG-531P 4.096 MHz Oscillator
(1) 74HCT4060 14 Stage Counter (4.096 MHz / 8192 = 500Hz)
(1) 74HC4017 Decade Counter (500Hz / 10 = 50Hz)
(2) 0.1" pin headers for test points (if desired)
Note, a 60Hz output can be generated instead by substituting the 4.096 MHz Oscillator for a 4.9152Mhz Oscillator (also SG-531P).
Schematic:
