- This is my first ZZ mod and my first time thinking seriously about learning SMD.
- I wanted more power for my ZZ, and I have seen lots of good mods. Since I want to keep reverse, I decided to monkey with the H-bridge. I decided to take a look at the circuit board and try out this mod,
http://tinyrc.com/forums/showthread....threadid=1736. The resistors to be bypassed were not connected to what I expected. They seem to be going to the gate of the mosfets. After i checked the voltage levels, I suspect that the transistors are not mosfets but are NPN and PNP transistors instead. There is a voltage doubler on the board (which can be used for other mods!) but I doubt this is for operation of mosfets.
- I couldn't find a schematic of the H-bridge so I have included my best guess as to the SMDs. R20 and R21 go to the low side transistor's bases and R16 and R19 go to the high side transistor's bases. R17 and R18 are pullup resistors (For stability?).
- Now for the mod: I highly suggest that the four driving resistors be lowered. I have gone ahead and shorted out R16,R19,R20 adn R21. Originally I could pull 80mA through the circuit. With the mod, I can now pull 150mA! The best part is I am only pulling 166mA from the battery. So I get over 4 minute run times and my ZZ can now run on carpet with red-red. Yaaaa! I also tried to give more power to the steering coils but their resistance is so high that I could only pull an extra 13mA. So I might change the magnet to a higher quality one instead.
- Here is another thought to those that really wan't a challenge. Use N channel and P channel mosfets that opperate at 3 volts; install another battery for the voltage to run it and you will then have a propper H-bridge.
- Anyway, my car runs better than ever. If anybody else experiments with changing the resistors or adding more transistors (you still can't get around the 0.2 voltage drop, I dont think) then please let let us know the results.