Anthony Roggenbuck

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On the left hand side of the breadboard is a five volt regulated power supply. On the right hand side, a 555 timer IC was used to generate a oscillating output causing a LED and or a buzzer to pulse on and off.

 

 

 

 

 

                   

 

 

 

 

This is the five volt regulated power supply that I soldiered to a universal PCB. I have been built several other power sources: 12 V regulated, and 1.5-28 volt adjustable power supplies.

 

 

 

 

 

 

Shown here is a pulse width modulator circuit. This circuit is used as a DC motor speed control. A 555 timer was again used to produce a oscillating pulse, but in this case it produces a much higher frequency output which can be adjusted by the potentiometer. A 555 timer can only source about 200 mA of current, which is not enough to power much of a motor. Therefore the signal from the timer is sent into a TIP 32 transistor which acts basically as a high speed relay in this case. The motor is then hooked up across the transistor and is turned on and off very rapidly and by adjusting the pulse width the average voltage the motor receives in turn determines the speed it turns.

 

 

 

 

 

 

 

 

 

 

 

 

In this circuit the transistor potentiometer combination is used to control the volume of the buzzer.

 

 

 

 

 

 

 

 

 

Here is another form of a DC motor speed control. Rather than using a pulse width to vary the speed, a potentiometer is used to directly vary the voltage. A small FET transistor is used as a trigger; when the potentiometer is turned all the way down the transistor kicks out and the motor turns off.

 

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Copyright 2007 Anthony Roggenbuck