For brakes I pretty much used what's available from the bikes that I had on hand. For the time being, I have one rear brake which is a centerpull (using a cable as a saddle between the two pads), using the same hardware that was originally on the rear triangle. The left rear wheel has the brake, the right rear wheel gets the pedal power.
The front brake was a centerpull cantilever, using a cable as a saddle between the two pads, which are set on hinges. Since I turned the stem around, I had no place to hold the brake cable vertical (one the bike, it was a hole in the center of the stem), so I discarded the centerpull setup. Instead, one of my (salvage) bikes had direct pull (V-brake) cantelever brakes, so I used that. Even with the correct hand levers (should be for a V-pull brake) I am not happy with that brake. I'll leave it for now.
Garage sales on Saturday, June 5, 2010, netted me a new inner tube, and a bike frame with a better bell, and nice looking sidepull brakes (like on some fancier bikes). Total cost $2.10. In a while I'll look into making the change.
Dual Rear Brakes. I would like dual rear brakes. In face, a mechanical engineer friend suggested forget about the front brakes, and have brakes on the two rear wheels. I'm strongly thinking of doing this. Unlike a bicycle, the trike has its centre of gravity (me, for the most part) low and far back. So in braking, the rider is not pivoted forward over the front wheel, at which time there is little weight on the back wheel, and thus little stopping power from the rear wheel. With a trike (especially this one) the most weight is over the back wheels.
So in fact a dual rear brake system might be the best.
I did hear of a device called a dual-pull brake lever. It enables a bicycle rider to control the front and rear brake with a single lever. We could use it to control the two rear brakes with one lever, and control the front brake separately with the other brake lever. Perhaps I could rig something up... But later.
Here are some pictures. (I finished the trike!)
In the picture below, the wheel closest to us has the brake. The cable runs over a pulley (originally on this bike) and down to the saddle which pulls the cable that swings the pads onto the rims. Sorry that it's hard to see.
(early June, 2010)