| RSFR may also be factory configured as "mixed" controllers when
purchased as a pair. One unit may be set up as the "right" motor and the
other unit as the "left" motor. Perfect for locomotion of 200-500 lb tank
drive robots. RSFR are compatible with most model R/C systems including PCM or FM
and plug into your receiver like a servo. They're available with Futaba J or G,
Airtronics, Deans, or JR connectors; please specify when ordering. The RDFR family
replaces our older DFRM type.
The optically isolated output is a Pulse Width Modulated full H-bridge circuits
originally designed for Permanent Magnet DC wheel chair motors. N-channel power MOSFETs
are paralleled in each H-bridge leg to achieve the specified amperage. For example: the
RSFR38 contains 48 70 Amp MOSFETs. In contrast to hobby controllers VANTEC's MOSFETs are
all properly thermally mounted flat to the metal heat dissapating case with special
insulating washers.
The driver PWModulates the bottom half of the bridge while holding the diagonal upper
bridge leg on in order to effect efficient re-circulating currents in the motor.
Sequenced electro-dynamic braking shunts the motor by modulating both top legs of the
bridge. With a command to "stop" the brake is gently ramped from 0 to 100% duty
cycle. When an R/C command that changes direction is received the brake is quickly
sequenced to first bring the motor to a halt, then the reversing PWM power is ramped up to
the commanded speed. This forced sequencing minimizes motor "plugging" and
stress on mechanical components. The implementation and timing of these functions is user
selectable.
Output current through the MOSFETransistors is compression limited above a threshhold
by PWM duty cycle limiting. There's a threshhold adjustment trimpot for each output. Some
short circuit protection is provided. |
