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Tested motors

The Spectral Micro drives three-phase brushless motors with a phase resistance of about 2 to 24 Ω: the calibration routine's default voltages are made for that range. The motors below have been run on it. Calibration measures each motor's resistance, inductance and pole pairs, so nothing has to be looked up before the first run.

Motor Kind Where
BGM8108 BGM8108 gimbal motor, 8108 class AliExpress
GM8112 GM8112 gimbal motor, 8112 class AliExpress
GM7008H GM7008H gimbal motor, 7008 class AliExpress
GM6008H GM6008H gimbal motor, 6008 class AliExpress
GBM5208 GBM5208 gimbal motor, 5208 class AliExpress
GM5208 GM5208 gimbal motor, 5208 class AliExpress
GBM5010 GBM5010 gimbal motor, 5010 class AliExpress
GB4114 GB4114 gimbal motor, 4114 class AliExpress
2804 2804 gimbal motor, 2804 class AliExpress
2804 (RCTimer) 2804 (RCTimer) gimbal motor, 2804 class AliExpress
2804 100KV 2804 100KV gimbal motor, 2804 class, 100 KV AliExpress
42BLS40-24-01 42BLS40-24-01 NEMA 17-format brushless motor, 24 V, 26 W, 1.8 A, 219 g Stepperonline

Before the first test, set the current limit for the motor with #Ilim: calibration leaves it at 1600 mA. The factory default of 1000 mA suits the gimbal motors above; a motor rated for more can go up to the driver's 2800 mA. See Current limit and loop tuning.

Choosing a motor

A lower phase resistance and inductance give a higher speed at a given supply voltage; the velocity constant KV that calibration finds tells how fast the motor can turn: roughly 0.8 × Vbus × KV revolutions per minute. A high pole-pair count (the large gimbal motors have 11 to 14) gives smooth torque at low speed and limits the top speed through the driver's maximum electrical frequency. Motors with visibly uneven windings, a resistance that differs between the phases or an uneven back-EMF calibrate badly and run rough.

Drone motors

Motors with a phase resistance well under 1 Ω draw a destructive current at the calibration routine's default voltages. The Spectral Micro is not made for them.

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