Detect the voltage AC signals of electric switch through Wireless Analog to Digital Converter

Thread Starter

daisy56

Joined Mar 30, 2018
8
Hi, I am using a Linux operating system as gateway receiver which is connected with ZigBee modem, I am thinking of using Wireless Analog to Digital Converter for converting the analog signal into digital.
My question arises when I started testing these wireless sensors with electrical switches.
What I really need is to send the 16 electrical switches power status one by one to wireless sensor which will further send the data to ZigBee modem, I need some analog circuit suggestions which will help me to receive the electric signals working on 120v.
Any leads will be a great help.
 

LesJones

Joined Jan 8, 2017
2,687
If you only need to know if the switch is on or off (As opposed to the actual voltage on the switch output) then I would suggest using opto isolators. You do not say if the 120 volts is AC or DC. If it is AC you can get some opto isolators that work with AC input. (They use two reverse connected LEDs.) Unless you need to measure the voltage you do not need an analogue input. You need 16 digital inputs so the simplest way do that would be to use a 16 input multiplexor to scan the 16 channels. The multiplexor would need 4 digital outputs to select the 16 inputs and one digital input to read the state of it's output. As you want a wireless link (I am assuming you mean Wi Fi rather than something like an HC-12 tranceiver.) an ESP8266 module could be programmed to do this.

Les.
 

Thread Starter

daisy56

Joined Mar 30, 2018
8
Hi, Thanks for the reply I was using these Wireless Analog to digital converters with thermistor earlier, the company is already using IEEE standards 802.15 devices for WPAN network.
Using opto-coupler seems to be the nice idea for controlling the brightness of the light can you please suggest the sample circuit which is easy to communicate with the Wireless A/D sensor?
which send the converted signal to gateway receivers?

for much better understanding I am sharing the manual of this sensor
 

LesJones

Joined Jan 8, 2017
2,687
I'm confused with your second post. Your first post is about sensing the on/off state of 16 switches. Your second post about controlling the brightness of lights seems totally unrelated to the first. The opto isolators were suggested for isolating the electronics from the 120 volt switched circuits. Each opto isolator would give a logic level signal from the 120 volts switched by the switches that you want to sense. You could think of them as relays with 120 volt coils (You can't connect 120 volts directly to the input side of the opto isolator. It has to be via a current limiting resistor.) and the contacts switching logic level signals. The only way I can think to use the analogue input would be to have a free running scanning circuit at the sending end. As the A to D has two channels you could send the address of the switch on the first channel as a voltage. If switch 1 was being sampled you would input 1 volt into channel 1. If switch 2 was being sampled you would input 2 volt into channel 1. And so on up to 16 volts. Channel 2 would be fed with zero volts if the switch was open and for example 10 volts if the switch was closed. It should be easy to interpret this at the receiving end.

Les.
 
Last edited:

rsjsouza

Joined Apr 21, 2014
253
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