Electronic speed control systems for miniature direct current motors
US4008426A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 20, 1975 |
| Grant date | Feb 15, 1977 |
| Priority date | — |
| Expiry date | Nov 20, 1995 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S388/902
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A miniature DC motor is connected to a DC source through a PNP type driving transistor. The back electromotive force of the motor which is proportional to the speed is applied to the base electrode of an NPN type control transistor through a variable resistor and the output of the control transistor is applied to the base electrode of the driving transistor through an NPN type amplifier transistor. A capacitor is connected between the base and emitter electrodes of the control transistor for smoothing the voltage applied to the base electrode of the control transistor. The sensitivity of the speed control system can be improved by connecting a Zener diode in the input circuit to the control transistor. Further the effect of the variation in the ambient temperature can be compensated for by using a thermister.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.