Friday, March 13, 2015

Mains Voltage Monitor

i need a circuit design to detect generator voltage and display with LED for certain value of voltage. for example red LED"s for voltage under 180 V, green LED for 180-220V and Yellow LED for voltage above 240 V. i would like be glad if you would like to help me design it!

mail from KB

I have some designs that may do that easily. Have a look at them. We could modify them to suit your needs.

First the 230V has to be brought down to say 2.3V with a transformer or attenuator. Then we have to measure it with LED bar graphs, choose color of LED as required. If the measurement unit is a sealed plastic box then it can be transformer less.

Look at these first. Mains Stabilizer Circuit, In DMM Circuits see ....analog and 3-1/2 digital display for +/- 199.9mV. in LM3914 you can light up a bar graph or a single LED to show the Level.

in Water Level Sensors see Fluid or Water Level Sensor using reed relays - circuit example

DPM based on ICL7107 see AC voltmeter digital, 7107, pdf After you looked at all the circuits, Tell me how i can help you.

DPM based on ICL7107


i have seen almost all the source you show me. i got more explanation and also more confusion...!
well, actually all i need is not too complicated but maybe its tricky for me. i got the idea about using voltage comparator via voltage divider, not using transformer like you said. it is more reliable and easier, isn"t? but again i got little bit trouble to design it!

is it easy for you anantha? i hope you will give me best solution for it! if you dont have mind i will wait for your design as comparison, but not in hurry! Ok, thank you for your kind attention!

mail from KB

I will make a circuit for you as soon as possible. Do you need just 3 LEDs or more. do you have experience in using 230V supply safely as it can give shock. give me more details if possible.


Again thank you very much for your attention on my question. actually it will be better to have 9 LEDS for 3 kinds. i have some experiences in installing 220/230 V but not expert, dont worry about that i will try as safe as possible.

i would like to install picohydro for my garden with power about 300 watt using induction generator. it will be expensive and not comparable to use complete controller as well. so i wondering to have voltage indication to estimate voltage condition, or even you have experiences with picohydro or minimum requirement for it (controlling, safety) like overvoltage protection, etc. again i will be glad for it....!
i will wait for your answers.

mail from KB

Can you please explain in brief what is picohydro and how induction generator is used. I have attached a circuit, It is not tested, It might do the job. You must have basic knowledge in building, testing and troubleshooting circuits.

After a study of the circuit you can tell me more clearly your needs.


Ok, induction machine can also used as generator if you at least:

1. Drive motor faster than synchronous speed (slip = negatif)
2. There is reactive power from outside (capacitor/Grid)
I think you know it! in my case i used 3 phase induction motor with 1 phase output only (C2C connection),its more reliable and much better than 3 phase output for small power! its easy to build! any way, thank you for your design...!i will try to study it before i build.

mail from KB

The circuits you asked for with some explanation has been published here.

Mains Voltage monitor using LM3914

Simple Mains Voltage monitor