Ok, here's what I did last night. I started trying to design the new circuit and realized I would need some kind of transistors to drive the motors, so I decided to go a different, but easier route. I checked the value of the potentiometer inside of the pseudoservo and it tested at 5K ohms. Then I took apart my existing servo, and did a little testing. Inside the potentiometer was reading at 2.6K ohms, but I figured it might have another resistor in parallel, which would drop the resistance, so I desoldered it from the circuit board (after carefully diagramming it) and retested the potentiometer. It tested at 5K ohms this time. So I went ahead and put the circuitry from my existing servo inside of the pseudo servo, so now it's a real servo. I reassembled the car and tested and it worked although I do need to recalibrate the remote for the new mechanics, but this should be a very good solution. I may build that circuit for my old servo in the future anyways because it would be a neat circuit to have available.

The car I got is a Nikko Super Megatron which was manufactured under a number of other models as well. One of them was manufactured for Radioshack as the Desert Viper (I looked at a parts diagram to confirm this). I remember that particular car from when I worked there 12 years ago and it was their most expensive car and if I remember correctly, it went for about $225 at the time.

One of the main reasons I liked going with this new chassis is that it held a 7.2V batter as opposed to the 9.6V one I had in the truck. Most of the commercially available ESCs (Electronic Speed Controllers) would only go up to 7.2V, so this gives me a much wider variety of to choose from. The next things I am going to try and get are a commercial ESC and a new battery (the one I have is probably at least 15 years old and I haven't used it for that long either). Then again, I successfully used another 9.6V battery that was about just as old, but it doesn't hurt to have 2 batteries. This should give me enough parts to get a basic RC car up and running.

The next step would be to start making logic boards for the brain of the robot. I have been toying around with the idea of just buying a commercially available board with a chip of my choice as well as a bunch of support circuitry. That way I could just take care of the programming, which is the portion I am looking forward to the most (although I do love the challenge of getting things working mechanically). However, if I do end up going with my own design, I think I will start by creating a breakout board for the processor (a circuit board to which an SMT chip is soldered so that wires can be connected to each separate pin of the chip). That way I can just hook it up to a bread board and develop a much better understanding of how it need to be hooked up as well as to be programmed. In fact, I could most likely just hook up the processor on the breakout board directly to my existing programmer. I still don't feel like mucking with an ESC at the moment, but if I feel I could build a more efficient one, I may go that route after getting the initial car running.