Steve,
this is a sensorless controller design, which means that you don't need a hall sensor on the coil. This allows to separate the two heat sources coil and driver. Also throttle control is better than on the A1442 and I believe my controller has a better efficiency. But not for Dan's motors since they don't run with my controller Seems like the timing is not covering high inductance motors. Just a question of adaptation...

Chris

Hi Chris,

I tested several of Dan's motors that he set me and they all ran with your controller. I am now wondering if it has something to do with the transmitter. I could not get your controller to work with my DX-8 transmitter, but it worked with my converted Plantraco Hip Hop transmitter. Maybe it is has something to do with the throttle settings. I know that you tested the controllers before you sent them out.

Joe.

Really? that is interesting. Maybe Dan can make a shot of the servo signal with his usb scope.

Chris

ChrisT

I presume your controller responds to plain vanilla servo pulses
(1 to 2 mec wide, every 22 msec or so)..

SteveH

ChrisT,


Also check out the TI DRV8835 dual hbridge, maybe that can drive a couple of your
servos.. Sort of like a better version of the a3901..

Pololu electronics has a test breakout board for these for 6 bucks..

http://www.pololu.com/catalog/product/2135

SteveH

Chris, the new capacitor arrived yesterday!

DRV8837 is running

Chris

Kool..hope it works out for you..

Check out the Drv8851. Ldo plus hbridge
Not available yet but looks worth tinkering with

I got my drv8835 test board from polulu today..
it seems to work aok as well..

SteveH

All

I know you guys are working on high
Rpm motors for the jet .. but i am interested
in this stuff to try to build motors for a nano size
Helicopter.. i know shagrug is the guru here on the
Motors and i was wondering if he or anyone else could
Speak about how to go about
designing the motors for that application..

More or less turns.. bigger or smaller wire...bigger or smaller magnet..etc..
Those are questions i wish somebody could try to address to steer me in the right
direction


SteveH

All..

Happy New Year to everybody!!!!



ChrisT,

When is the optimum time to turn on the hbridge to
maximize the amount of torque applied to the magnet?
I would think it would be closet when the poles of the radially polarized magnet
are not othrogonal to the motor windings electromagnetic field..

Is what you are trying to do is measure the measure the back emf
to determine the rotor position so you know when to apply the current
to the motor? and use pwm to control the speed?

I am kinda new to this brushless motor stuff..

SteveH

Happy new year too to everybody!

I think I found something on the controller. While developing the new rx, I figured that if the rx goes crazy during motor start, the pulse width of the motor control can increase severely, most likely due to the fact that there are multiple edges on the rx line triggering the ppm read sequence by the pin change interrupt. This way, switching off the coil in time is delayed and supply voltage is dropping enough to reset the atmel while the coil is drawing the current. I am now making a start routine that is only triggered by the ppm signal, but during startup, the ppm signal is ignored until I am in sync mode. This mode disturbes the radio signal much less (not at all for me). So the performance of the actual controller code is dependent on the behavior of the rx during disturbance and this might explain the different experience you guys had with the c3blc1. Seems like it is time for a c3blc2 with the new bridge

Chris

P.S.: Just to get it straight: I caused the multiple edges by switching off the tx and running a start routine that wouldn't read throttle from the ppm signal. Still a high frequency on the ppm line, which you get without a radio signal, did increase the pulse width.

Servo installed and working. ..

Sweet!!!

fan design

first 3D shot