i need to measure ac voltage any idea??

Status
Not open for further replies.
D

Deexith Hasan

Advanced Member level 4
Joined
Oct 24, 2014
Messages
111
Helped
4
Reputation
8
Reaction score
3
Trophy points
18
Visit site
Activity points
740
i need o\p 210-240 v ac if greater than or lesser than this value i have to turn off relay???

i used 220-12v transformer & rectifier & voltage divider to give 2.5 volt for 230v ac but relay should be turn on if adc value is between 2.4 to 2.6 ie(210-240) diff is +-0.5 which is difficult & inaccurate...

i need some other idea to measure ac & disp in lcd
 

First of all, how did you subtract 2.4 from 2.6 and get +/- .5? Secondly, if 230V gives 2.5V, then 210->2.3V not 2.4. Maybe your whole problem can be traced to arithmetic.

You've got a 300mV differential, this is well within the capabilities of even a simple 8-bit ADC to resolve. If you've got enough filtering, I don't see where your problem is.
 
You can subtract some volts by putting a zener diode inline (or led's, diodes). This gives you an expanded scale at the output.

Relays usually open a few volts below the voltage where they close.
 

using transformer input is 220 o\p 12 volt rms. bridge drop is 1.4v [full wave rectifier] so o\p is 10.6 volt...
how to find the filter capacitor needed ?

10.6 volt rms after filtering i should get 10.6*sq.root (2)=14.9 volt but getting 8.98v.....in proteus. y???
 

Deexith Hasan said:
using transformer input is 220 o\p 12 volt rms. bridge drop is 1.4v [full wave rectifier] so o\p is 10.6 volt...
how to find the filter capacitor needed ?
Click to expand...
Depends entirely on:
1) How much ripple you can tolerate
2) Load

If you've got no load, you can use a very small cap.
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…