# AC to DC

Discussion in 'The Projects Forum' started by fengyun, Jan 17, 2014.

1. ### fengyun Thread Starter New Member

Oct 2, 2013
2
0
Hi everyone, I am trying to monitor the current output of the 230v socket outlet using current sensor and a Monitoring system and its equipped with transmitter (4-20mA).
Once it reach over 20mA it will indicate as overload.

The voltage across the 500ohms resistor (parallel with the current transformer) is 0.449vac at 1A. and 2.245vac at 5A.

how do i convert AC voltage to output DC 1-5v? I wan 1-5vdc because of the transmitter.

I tried the circuit showed in the link but it doesn't work for me. The circuit they used is 0-50A and output is 3vdc, the diode i used is IN4007. I do not understand the calculation of the circuit.

https://forum.sparkfun.com/viewtopic.php?f=14&t=28775&start=15#p129154

Transformer im using: http://www.mouser.com/catalog/specsheets/CST-1005.pdf

Thank you!

2. ### MikeML AAC Fanatic!

Oct 2, 2009
5,451
1,070
Replace the 1n4007 power rectifier with a small-signal high-speed switching diode 1N4148 (or 1N914).

Do you have the negative supply voltage for the opamp?

3. ### fengyun Thread Starter New Member

Oct 2, 2013
2
0
Thanks for pointing out the negative 5v, now i supplied supplied the op amp with -5v and changed the diode to 1N914 ( i do not have IN4148)

now the multimeter shows the output of the op amp is 3vdc but its not stable, the osilloscope shows there is saturation

how do i calculate such that i can have 1-5vdc at the output?

4. ### MaxHeadRoom Expert

Jul 18, 2013
12,887
3,521
Remember you can decrease the turns ratio by adding a turn or more on the input side, take the conductor through twice or more.
Max.