![]() When these outputs are given to stepper motor coils through ULN2003A chip the stepper motor will start rotating. Likewise outputs C and D are of frequency F/4 and F/8. Similar to that 2 nd and 6 th outputs of counter are given as inputs to 2 nd OR gate so its output at B will be F/2. Because 1 st and 5 th output are given to 1 st or gate inputs, its final output at A is of frequency F shown as second waveform. When it is applied to decade counter it generates 10 pulse trains of frequencies F, F/2, F/4, F/8 likewise. IC555 generates pulses at frequency F shown as 1 st waveform. 2: Image showing Circuit Operations in Waveform The circuit operation can be explained better with the help of following waveforms.įig. ULN2003A has darlington pairs inside which drives the stepper motor coils. The outputs or all 4 OR gates are given to inputs of ULN2003A. ![]() 5 th output is again given to second input of 1 st OR gate and likewise remaining 6 th, 7 th and 8 th outputs are given to rest of gates. Like as shown in figure, 1 st output is given to one input of 1 st OR gate, 2 nd output is given to one input of 2 nd OR gate and likewise 3 rd output and 4 th output to 3 rd and 4 th OR gate respectively. Out of these 10 outputs, 8 outputs are given as inputs to 4 OR gates of 74LS32 that they will generate only 4 outputs with F, F/2, F/4, and F/8. If input frequency is F the counter will generate 10 outputs with F, F/2, F/4, F/8 …. Output of IC555 is connected to clock input of counter CD4017. ( the frequency variation is very low because the RPM variation is multiplied by 60 so RPM variation will be 120 to 180) The values are selected such that output frequency varies from 2 Hz to 3 Hz. Pot R3 is used to vary frequency of output pulses. Its RC timing components are R1, R2, R3 and C1. Current Driver ULN2003 – Used to amplify output current of OR gates to drive stepper motor coils ![]() OR Gate 74LS32 – It is used to generate 4 pulse trains of frequencies f/2, f/4, f/8 and f/16Ĥ. Decade Counter CD4017 – Used to divide the frequency of pulses generated by IC555 and generate different frequency pulse trains like f/2, f/4, f/8 … etcģ. IC555 – Used to generate sequence of pulses with variable frequencyĢ. 1: Prototype of Simple Stepper Motor Driver using 555 Timer IC Circuit on BreadboardĪs shown in the circuit diagram the circuit is implemented using following chipsġ. That is why the name given simple stepper motor driver.įig. ![]() It drives stepper motor using simple, easily available and commonly used components and ICs like IC555, decade counter, OR gate, current driver chip etc. It does not use any micro controller (or micro processor) or any programmable digital device also it does not require any software program to generate sequence of pulses. The circuit presented here rotates stepper motor and varies its RPM (speed). ![]()
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