HOw to use IC555 as ADC by control pin 5

[hbaocr]

hello,
can any body tell me how to use IC555 as ADC by controling voltage in put on pin 5 of IC 555.
And the relation between voltage on pin 5 and the pulse output
thank

 

[IanP]

You can try to configure 555 as voltage-to-frequency(time) converter ..
The voltage can be fed through pin 5 (ac only), but here is much better concept:
**broken link removed**

Regards,
IanP

 

[osores_r]

you can use the 555 like a outpout PWM on de pin 3, Where this is output you can controller by the pin 5 this is a comparator with two level of de voltage

 

[smiles]

If there is an voltage on pin 5, it seems approximate to triangle signals, you can compare it to with another signal via OPAMP

 

[hbaocr]

thank
but I want to know exacily the relation between volage on pin 5 and pulses out put on pin 3.
and what the equation of it is

 

[A.Anand Srinivasan]

the voltage at pin5 determines when the output at pin3 is supposed to switch back(transition).....

 

[hbaocr]

thank A.Anand Srinivasan
If u don't mind plZ tell me more detail about the voltage at pin5 determines when the output at pin3 is supposed to switch back
Which level voltage on pin 5 to switch pulse at pin 3

 

[IanP]

The output (pin3) goes HIGH when the voltage at pins 2 and 6 is below 1/2V(pin5) and jumps back to LOW when the voltage at pins 2 and 6 reaches V(pin5) .. see internal diagram of the 555 timer - there is 2-resistor ladder between pin5 and GND ..

Increasing the input voltage at pin 5 decreases the output oscillation frequency while decreasing the input voltage increases the output oscillation frequency ..

Regards,
IanP

 

[A.Anand Srinivasan]

given below is the block diagram of the 555 IC in that you can see that the upper comparators input is given from pin 5 and hence when that voltage is exceeded by the voltage at the pin 6 the comparator switches off the Flip Flop and hence the pulse width is directly proportional to the voltage at pin 5....

 

[hbaocr]

thank for your helping! I have search on internet! and I Find a result that:
voltage on pin 5 = 26150/pulse + 2.5

plz explain it to me. Why does we have that result

 

[A.Anand Srinivasan]

can you please post the link that you found this result in... because i'm confused about this result... i would like to go through what it is all about....

 

[hbaocr]

hi, here that link

**broken link removed**
plz tel me more the reason why that result is voltage on pin 5 = 26150/pulse + 2.5

 

[A.Anand Srinivasan]

actually in that circuit it is assumed that the voltage at pin2 is 2.5V due to the capacitor and the output is 2092 pulses when a input of 15V(pin5) is given...
so 15-2.5V=1/2092 pulses(time period)
so when the difference between pin2 and pin5 is x volts(input) the output would be (2092*(15-2.5))/pulses) volts and adding the 2.5V offset due to the capacitor we get 26150/pulse+2.5V...

 

[microteck]

all aplication of ic 555