Stepper Motor

M1 is a stepper taken from an old disk drive. There are five pins, i.e., common, coil 1, 2, 3 and 4. Resistance measured between common pin and each coil is about 75 Ohms. Driving current for each coil is then needed about 60mA at +5V supply. A darlington transistor array, ULN2003 is used to increase driving capacity of the 2051 chip. Each output provides 500mA max at 50V. P1.4 to P1.7, four output pins are connected to the input of the ULN2003 as shown in the circuit. Four 4.7k resistors help the 2051 to provide more sourcing current from the +5V supply. The serial port is optional for your exercises. Many have provided useful technical, and application of using stepper, see the links below...

The 74AC240 stepper driver works by alternately enabling each half of the buffer. Only one half can be enabled at a time. Let`s assume that the top half of the driver is enabled. U1A & U1B along with R8, C1, and the input protection resistor R7 form a square wave oscillator. The outputs of U1A & U1B directly drive one coil of a bipolar stepper motor...

When I build up this card, the 74*86 IC is "socketed," both to protect the IC during soldering, and to allow for experimentation with IC subfamily. Similarly, the timing resistors and timing capacitors are plugged into individual sockets to allow for tinkering with circuit timing (i.e., motor rotation speed)...

You can, though, use this circuit to drive any bipolar or unipolar (via bipolar drive) stepper motor. In the Solarbotics diagram, the Yellow and Blue leads are the end contacts of one motor winding, and the Red and White leads are the end contacts of the other motor winding. In the case of the unipolar motor that Solarbotics sold, an additional two Green leads were the two windings` center taps, and left unconnected...

One of my student has made a disgraceful robot that used two stepper motors and with a simple IR sensor. Yes, above picture is what I`m talking. Without battery carrying, a little bit torque of the stepper and misalignment of driving shaft, makes it crawling not walking, but first demo, showed quite impressive to me. He said he wrote a couple of program lines using C, his robot can track the black tape. I feel delighted his intention and endeavor. I thought, " he borrowed me DS5000, expensive one, a soft uController with internal bootloader, why shouldn`t try with our learning board C-52 Evaluation Board instead"...

So he always stays on course, Jared designed a mechatronic device that simulates perfect steering in an automobile. The small-scale, single-wheel model determines the speed of wheel rotation from the magnitude of the curve it`s traveling. It works by setting the initial speed of a PIC-controlled dc motor, then uses a manual-input turn radius to vary the speed of the motor and advance a PIC-controlled stepper motor one visible step (7.5 deg) in the specified direction...

As you can see this is a fairly complex formula, but with a little bit of work and some math it is possible to compute with the Stamp. Figure 1 shows the non-linear relationship of pressure vs. altitude. As you can see on the graph as pressure decreases, altitude increases, but the higher the altitude gets the less pressure changes. In other words the higher the altitude gets the stepper the slope of the curve gets. That is what gives the curve its non-linearity...

This is a voltage controller oscillator that was designed as a wide range oscillator to generate clock pulses for a stepper motor drive system. It does however have some interesting features. The original application used a stepper motor for its ability to operate over a very wide speed range, so this oscillator is also designed for a very wide frequency range...

This is an image Schematic. No Description available...

Typical stepper-motor control circuits use either logic gates and flip-flops or shift registers to generate the proper sequences of binary codes that produce bidirectional stepper-motor movement. A conventional stepper-motor-control circuit uses a square-wave generator, a sequence generator, or a shift register and current translators to control one stepper motor apart from the logic circuit necessary for producing a known and valid binary code at start-up...