Aquarius

Background

When I got back into the Aquarius in the Summer of 2019, I got a bare bones Aquarius that didn't even have the switch box or cable plug for RF output. I had to hack together a BNC cable with an RCA cable to even see the output to make sure the machine worked. It was frustrating, so I began researching the raw VID (composite) signal coming off of the video chip (TEA1002) of the Aquarius. I hooked a standard composite cable up to it but found the signal was too weak to be useful. I then found a video showing one user's success at adding an inexpensive video op-amplifier, and set about trying to find a similar chip in a more manageable PDIP-8 package that most users could more easily solder. I settled on the AD812ANZ Video Amplifier chip. Included in the chip's documentation was a sample single-supply (+5v) circuit, so I assembled the parts, bread-boarded it, and hooked it up. It worked on the first try. I then found the SND lead and discovered that it didn't need to be amplified, so I passed it straight through to the right and left audio out. After that success, I went through two PCB prototypes and settled on a design that fit within the stock RF modulator's form factor.

Purchasing

The Aquarius Composite Video Adapter Board is available from PCBWay at the link below:

https://www.pcbway.com/project/shareproject/Aquarius_Computer_Composite_AV_Adapter.html

In addition, you'll need to get the components necessary to build the board, listed in the BOM (Bill of Materials) below. Note that there are both US and UK/EU tabs for the BOM.

Development Details

While I would LOVE to claim to be an electronics genius (not even close!), I relied on the support of friends and colleagues in developing this board. First, the composite amp circuit is taken DIRECTLY from the spec sheet of the AD812 video amp chip used to boost the signal. I wanted this board to be DIY, so I focused on THROUGH-HOLE components. And the circuit I used is identical to the one on page 16 of this PDF (Figure 53. Biasing for Single Supply Operation)...

The only real "magic" I performed was in taking detailed measurements of what the size and shape of the PCB would be so that it could be a drop-in replacement for the stock RF modulator. I also figured out a way to use a more standard 1/8"/3mm AV cable, and make sure that it centers itself in the TV port on the back of the Aquarius. But truth be told, anyone with a bit of electronics hobbyist experience could have done this as well.