User Manual

Version 1.0 - May 26, 2011
6
The internal voltage regulator of the Wasp is a National Semi LM2940IMP-5.0 regulator. This
is a linear type regulator and generates significant heat when the difference between the
battery voltage and the 5.0V regulated output voltage is large. If the voltage regulator gets
too hot it will shut off to prevent damage. This disables the Wasp since the internal CPU uses
the output of the regulator. The Wasp has been tested up to 21V input without overloading
the regulator. For battery voltage above 21V it is recommended to use an external 5V supply
connected through the RC cable (receiver battery or BEC) and clip the 5V disable loop on the
Wasp.
5. Warnings
The following warnings should be heeded when using the Wasp to avoid failure of the device:
1. Bench type power supplies do not tolerate regenerative current i.e. current flowing
back into the power supply. Often their voltage will increase until the extra power is
dissipated. If the Wasp is operated at 24V with a power supply of this type it is
possible to exceed the maximum rating of the device and destroy the power chips.
When using a bench supply it is recommended that you operate at a lower voltage
Adding a battery in parallel with the output of the bench supply will provide a buffer
which can absorb the extra energy and avoid this type of failure.
2. Sensible driving of the load will increase the life of both the electronics and the motor.
Do not repeatedly switch instantly from full forward to full reverse. If possible reduce
the applied load voltage gradually. This allows the inductive energy in the circuit to
dissipate without the inductive voltage “kick” that often occurs on abrupt interruption of
the load current. When using a bench supply even switching from full speed to full
stop may cause an inductive kick that can damage the device if the operating voltage
is close to the upper limit.
3. Monitor the device temperatures. The power chips will protect themselves against
overloads but repeated operation until the over temperature or current protection
circuits are activated will shorten the life of the device. Add a fan to speed the cooling
and increase current capacity. During development and testing the devices should not
exceed 100C (painful to the touch) or they may exceed the operating temperature
limits during extended use.
4. In general short thick wires are your friends when using any electronic speed control.
Thin, frayed or poorly soldered wires will provide a poor connection to the load and
cause less than 100% performance and reduce reliability. Good polarized connectors
and a properly rated power switch will also help with good reliability and performance.
6. Dimensions and Mounting