September 22, 2012
I was able to remove the chip from the RC car receiver board, but I didn't have the dexterity and soldering skills to solder leads into the tiny board to use the ready made h-bridge. My next step was to try and build my own h-bridge, but that isn't working out very well.
I tried to follow this design for an h-bridge. First, I built the whole circuit and tested it out. The motor didn't even hiccup. Next, I tried testing one section at a time. I started out with the PNP. I am using a 2n4403. Here is the Multisim schematic with simulation results for PNP circuit as well as a picture of the actual circuit on my breadboard.
PNP Schematic with Simulation Results
Real PNP Circuit
Once again, the motor didn't move. After pulling my hair out for a while and reading my electronics textbook I gave it a rest and moved onto the NPN. I am using a 2n2222a. Here is the Multisim schematic with simulation results for NPN circuit as well as a picture of the actual circuit on my breadboard.
NPN Schematic with Simulation Results
Real NPN Circuit
The single NPN transistor circuit worked great. The motor was running like it was connected straight to the power source. So, I decided to use only NPN transistors and see if that would work. I made half the bridge to test it out. Again, here is simulation and real.
NPN Double Switch Schematic with Simulation Results
NPN Double Switch Real Circuit
The NPN double switch didn't work. I know I am doing something wrong. I just don't know what it is. I ordered this h-bridge in case I can't figure this out and also because it seems that it would take up much less space compared to the components I would be using to make my own. I also have my eye on the kit that OddBot mentioned. If anyone has some advice I would really appreciate it.
EDIT 9/22/2012: Well I got the half bridge to work using the design mentioned in the beggining. Expanding to a full h-bridge now to see how that works.
EDIT 9/22/2012 again: Yeah, the whole problem was my BJT's. Some of them are broken. Full h-bridge according to the design mentioned above is working now. Next step, obstacle detection.