Energy consumption meter - Page 1
Forum section: electronics / beginners

author: banksofitaly
author_rank: Newbie
timestamp: July 18, 2018, 09:38:32 pm
content: Hello.I'm a complete newbie to electronics, but I've been studying by myself and trying to see if I could design my own energy consumption meter. The idea is simple; the electrical service panel in the house has an LED indicator that blinks 10,000 times for every kWh of electrical energy consumed (once per 0,1 Wh). My circuit consists of a photoresistor that feeds an op amp negative input. The output of the op amp goes into a Schmitt trigger that has a potentiometer for calibrating the comparison voltage (V_COMP) based on ambient lightning, the LED brightness and such. When the LED indicator on the panel lights up, the resistance of the photoresistor goes down, V_IN goes down below V_COMP and V_OUT goes up (ideally to V+? but with VCC of 9 V I'v measured V_OUT at about 7.7 V).The output of the op amp also goes to an onboard LED indicator (which blinks every time a blink on in the service panel has been detected) and through a 5 V voltage regulator to an Arduino Nano, which counts the blinking frequency and displays the current electricity consumption on an LCD. The idea is to later add a portable display unit that receives the consumption information from the main unit wirelessly (probably RF?), but I'm not that far yet.I've tested this circuit on a breadboard and it seems to work fine, so I wanted to make a prototype PCB for a proper field test. But before having the PCB manufactured I wanted to see if anyone could have a look at my design and point out all the horrible mistakes and stupid decisions I've made when it comes to the circuit diagram or the PCB.Thank you in advance.

author: JS
author_rank: Frequent Contributor
timestamp: July 19, 2018, 12:13:13 am
content: I don't think the electric company will be thrilled for you to putting something on there, you should probably get a device to measure again and go from there.Here is a link for one, like $7 and do work nice. A bit more if you want to see power factor and frequency.https://www.aliexpress.com/item/1pc-New-1pc-AC-80-260V-LCD-Digital-20A-Volt-Watt-Power-Meter-Ammeter-Voltmeter/32663481093.html?spm=2114.search0604.3.69.6db355feaWOXJo&ws_ab_test=searchweb0_0,searchweb201602_3_10152_10065_10151_10344_10068_10342_10547_10343_10340_10059_10341_10548_10696_100031_5723415_10084_10083_10103_10618_10307_10624_10623_10622_10621_10620,searchweb201603_13,ppcSwitch_5&algo_expid=a514fb75-3614-4b87-bbad-698345367936-13&algo_pvid=a514fb75-3614-4b87-bbad-698345367936&transAbTest=ae803_1&priceBeautifyAB=0Maybe you can hack something in to get the wireless connection, or search a bit more and find one it already does, or at least has a serial output.JS

author: banksofitaly
author_rank: Newbie
timestamp: July 19, 2018, 07:13:47 am
content: Thanks for your reply.I wouldn't think the electric company should have a problem with it, since the only thing I'm adding to the electric panel is a photoresistor that's attached to the end of a cable. The rest of the device can stay on a shelf. There's also nothing physically connected to the electrical system of the house (except an AC adapter, of course, to power the device).There are already commercial products that do essentially the same thing available (that's how I got the idea), but I wanted to see if I could make one by myself.