LM555 as variable frequency oscillator

Thread Starter

xyz9915

Joined Feb 24, 2008
23
Hello!
I need a circuit in which the frequency of LM555 astable multivibrator can be controlled externally I mean by the help of transistor etc. So, please guide what modification may be done in the attached circuit
 

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bertus

Joined Apr 5, 2008
19,947
Hello,

Pin 5 of the 555 os called CV (control voltage).
When you put a resistor of 1K to that pin and give a voltage to the other side of the resistor, you can influence the triggerpoints of the 555.
This will result in a frequency change controlled by tha applied voltage.

Greetings,
Bertus
 
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