OK Steve, sometimes I'm a bit 'thick" when it comes to electronics. I have zero experience with H-bridges and MOSFETs in general. Are you saying that this will do the job?
http://130.94.182.150/servo.jpg Seems vastly overpowered for my app, but I'll give it a go. I assume that the ".2" beside the capacitor is .2 micro farads. I also wonder about substitutions for the MOSFETs. If I used smaller MOSFETs, would it all still work? What about 2 N-channel and 2 P-channel, rather than 2 and 4? And what of voltage, is this not an issue? Seems kind of important to me. And why build a 38 amp H-bridge, then call out "three good gearmotors for steering servos" none of which draws more than 750 mA, like these guys have done? Seems like a bit of overkill. Paul H. ----- Original Message ----- From: "Steve Tyng" <steve...@gmail.com> To: "R/C Tank Combat" <rctankcombat@googlegroups.com> Sent: Saturday, February 28, 2009 11:15 AM Subject: [TANKS] Re: High Power Servo Hack > > Paul, > > The Pololu board would not work to "amplify" the current capability of > a standard r/c servo. The Pololu board is a bit to intelligent in > that it has it's own processing capability and determines motor speed > and direction via separate PWM and direction signals. Though the > Pololu board has an h-bridge the board itself is not controlled like a > typical h-bridge circuit. It is meant to be controlled be a > microprocessor and not as something as crude as a hacked hobby servo. > > The hack we are discussing replaces the internal and very basic h- > bridge circuit of the servo with an external higher capacity circuit. > This h-bridge circuit requires a PWM speed signal on one of either two > inputs unlike the Pololu board which has only one input for the PWM > speed signal and a second to determine direction. > > Simple h-bridge boards a few and far between. The Tecel was one, > RobotPower simple h-bridge is the only other commercial h-bridge that > I can recall offhand. Most servo hacks off this type I've read about > usually involves making a custom h-bridge board, which actually isn't > very difficult to do. Here's a link for one such project. > > http://130.94.182.150/mowers.htm (scroll down to "CONVERTING STANDARD > R/C SERVOS INTO MONSTER SERVOS") > > > Steve Tyng > > > > > --~--~---------~--~----~------------~-------~--~----~ You are currently subscribed to the "R/C Tank Combat" group. To post a message, send email to rctankcombat@googlegroups.com To unsubscribe, send email to rctankcombat-unsubscr...@googlegroups.com Visit the group at http://groups.google.com/group/rctankcombat -~----------~----~----~----~------~----~------~--~---
