The 555 astable multivibrator can be used as a free running ramp generator. when the frequency determining network Ra and Rb in the 555 astable multivibrator is replaced by a Current mirror.
Figure shows the circuit diagram for free running ramp generator.
The current mirror starts charging capacitor C toward Vcc at a constant rate. When voltage across capacitor C equals 2/3 Vcc (Vcc-5V), comparator 1 turns transistor Q1 on, and C rapidly discharges through Q1. However, When the discharge voltage across C is approximately equal to 1/3 Vcc, comparator 2 switches the transistor Q1 off, and then capacitor C starts charging up again. Thus the charge-discharge cycle keeps repeating.
OUTPUT WAVE FORM-RAMP GENERATOR
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SINE WAVE GENERATOR CIRCUIT
Figure shows the circuit diagram for free running ramp generator.
The current mirror starts charging capacitor C toward Vcc at a constant rate. When voltage across capacitor C equals 2/3 Vcc (Vcc-5V), comparator 1 turns transistor Q1 on, and C rapidly discharges through Q1. However, When the discharge voltage across C is approximately equal to 1/3 Vcc, comparator 2 switches the transistor Q1 off, and then capacitor C starts charging up again. Thus the charge-discharge cycle keeps repeating.
OUTPUT WAVE FORM-RAMP GENERATOR
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SINE WAVE GENERATOR CIRCUIT
6 comments:
i like it
www.streampowers.blogspot.com
Thank You
i want more ideas on led pls
Hi Pravin Kumar,
You can try our Led Emergency Lamp Project. We will update the site with more circuits related to LED, shortly.
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Nice article..
Feel free to check out our interesting Android Blog
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www.streampowers.blogspot.com is realy good web site for electronic engineers
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