- Discrete LEDs
- Dot/Bar LEDs
- Matrix LEDs
- 7-Seg LEDs
- Serial -- Software
- Serial -- Hardware
- RS-232 via the MAX3232
- I2C -- EEPROM
- I2C -- DS1307 Real Time Clock
- 1-Wire -- DS18B20, Powered, Single-Drop
- 1-Wire -- DS18B20, Powered, Multi-Drop
- 1-Wire -- DS18B20, Parasitic, Multi-Drop
- TI Link Protocol -- Calculator Demo
- Infrared Communication
- MIDI -- Output Demo
- MIDI -- Input Demo
- MIDI to Analog Synth
Motor Direction Control #1
Let's turn our attention now to the business of reversing the direction of a DC motor. The first idea that comes to mind is simply to reverse the polarity of the source driving the motor. A DPDT relay is ideal for this.
Since relays are inductive in nature, we'll include a back-biased rectifier to snub negative spikes which might harm the transistor otherwise.
Simple? You betcha. And it works. Still, it may not be the best avenue for any but the smallest motors. The problem is that the reversal occurs rather abruptly. The motor is turning at full speed when asked to shift into reverse. In the next exercise we'll see a more fluid way to deal with this.
And just so you know, All Electronics is a good source of relays, as well as DC motors.
Click to get the source code.
Click to get the schematic PDF.
Next Project: Motor Direction Control #2