On 9/12/2010 12:28 AM, RJ Kanary wrote:
<The E-15 doesn't have a stupid shunt, why does the E20 have one??> Different approach to controlling things.The early E-20 made an attempt to prevent field weakening at a inopportune time by measuring armature draw. The E-15 had time delays to try to do the same thing.The E-20 approach actually DID work,(Although I've disabled it on mine.), the way things were done on the E-15 never struck me as being worth the bother. :)
Oh, is that why they did it? I thought it was to keep the motor from melting down, but it sounds like it was there to prevent a wheelie.
On the older E12's, the concept was to use the centrifugal switch on the rear to not allow you to go into full power unless the motor was spinning. One could bypass this with "power pulse" since otherwise you could just sit there heating up the resistors instead of doing anything.
Later E12's seem to use the timing of an resistor/capacitor circuit triggering an SCR once charged to provide the delay. Which is cheaper than putting in a switch and a clutch. But if the capacitor shorts the time goes to zero.
I'll just keep out of the top speeds when starting until I replace the transistors.
C