I decided it was time to make some kind of replacement for the bulky Amiga 500 RF modulator. This little thing has a nice composite output and a S-VIDEO output for great video quality. Unfortunately, the female DB-23 connectors are hard to find, so I wont be making many of these.
I figured the AD724 would do nicely.
A little about the AD724:
The AD724 is a low cost RGB to NTSC/PAL Encoder that converts red, green and blue color component signals into their corresponding luminance (baseband amplitude) and chrominance (subcarrier amplitude and phase) signals in accordance with either NTSC or PAL standards. These two outputs are also combined to provide composite video output. All three outputs can simultaneously drive 75 Ω, reverse-terminated cables. All logical inputs are TTL, 3V and 5V CMOS compatible.
I do have several PCBs and parts available, but since the DB-23 connectors are not easily available, I will only post the PCB for sale.
Parts list: (position, value, size)
C1 100n 0805
C2 100n 0805
C3 100n 0805
C7 15p 0805*
C8 100n 0805
Q1 X-tal 4.433619 MHz for PAL, 3.579545MHz for NTSC
R1 75 0805
R2 75 0805
R3 75 0805
R4 75 0805
R5 75 0805
R6 75 0805
U1 AD724 SOIC16W
VIDEO TOBU3 TOBU3
DSUB 23 Female
*Only one of these to be used, eighter one 15pF at C7, or one adjustable one at C10
The PCB is default PAL (pin 1 low), but you can pull pin 1 on the AD724 high to select NTSC. (PAL is low and NTSC is high)
This PCB has not been tested in NTSC mode.
This project PCB can be purchased on ebay: https://www.ebay.com/usr/kirsti_73
or from Sellmyretro.com