Sensor Used to Light up an LED

Thread Starter

jeff77789

Joined Feb 22, 2013
18
So you guys have to pardon my ignorance since i am new here...and new to general electronics as well but hopefully what i will say will make sense once you get to the end of it

Basically, I have this sensor that takes a reading. This reading is a voltage and it can range from 0 mV to 2490.2 mV. This reading is going to be transferred wirelessly over 20ft to a receiver in which it interprets the data and acts as a switch to turn an LED on or off. The threshold voltage for this is going to be 1171.9 mV. When the voltage drops below 1171.9 mV, the light needs to turn on. (In the image, i wrote 2 volts but it is actually 1172 mV)

The sensor/transmitter unit is powered by 14v DC and the receiver/LED unit is powered by 9v DC. There is actually 2 sensor units and 1 receiver unit. I plan on using RF links with different frequencies for the 2 Tx/Rx pairs to transfer data.




What I circled in black is what I am having an issue with. I need components that will encode the analog output into something that the rf link can send (i also think that the AN output needs to be grounded but i am not sure about that)

on the receiver side, i need something that can interpret the signal being transferred over, set a threshold of <1172 mV, and then act as a switch for the LED



bonus:
it would be nice if the LED's would start flashing if the voltage was <586 mV
it would also be nice if the voltage threshold could be variable by a potentiometer

^those would be nice, but i guess that's out of my knowledge to implement

thanks in advance everybody!
 

MrChips

Joined Oct 2, 2009
30,824
What are you using as the transmitter and the receiver?
What you are asking for is easily done with a microcontroller.
Is this option open to you?
Do you know how to program and apply a microcontroller?
 

Thread Starter

jeff77789

Joined Feb 22, 2013
18
What are you using as the transmitter and the receiver?
What you are asking for is easily done with a microcontroller.
Is this option open to you?
Do you know how to program and apply a microcontroller?
I plan on using a simple RF transmitter/receiver pair with two different frequencies:
https://www.sparkfun.com/products/10532
https://www.sparkfun.com/products/10534

The option is open to me. the only thing preventing me from going that route is how to program and apply a microcontroller and how that will go along with the rest of the circuit
 

MrChips

Joined Oct 2, 2009
30,824
In order to use that transmitter/receiver pair to send digitally encoded information you will definitely need a pair of microcontrollers.

You do not need to use two frequencies. Neither do you need two transmitter/receiver pairs. One will do.

Have you used microcontrollers before?
 

Thread Starter

jeff77789

Joined Feb 22, 2013
18
In order to use that transmitter/receiver pair to send digitally encoded information you will definitely need a pair of microcontrollers.

You do not need to use two frequencies. Neither do you need two transmitter/receiver pairs. One will do.

Have you used microcontrollers before?
no i have never used microcontrollers before

i wrote X2 because I am actually going to be using 2 sensor units. therefore i will be sending information from 2 places to receive at one place. i said i needed 2 pairs at different frequencies so that these will not interfere with each other



now, the sensor actually also has a "Tx" output in which it outputs:
delivers
asynchronous serial with an RS232 format, except voltages are 0-Vcc.
The output is an ASCII capital “R”, followed by three ASCII character
digits representing the range in inches up to a maximum of 255,
followed by a carriage return (ASCII 13). The baud rate is 9600, 8
bits, no parity, with one stop bit. Although the voltage of 0-Vcc is
outside the RS232 standard, most RS232 devices have sufficient
margin to read 0-Vcc serial data. If standard voltage level RS232 is
desired, invert, and connect an RS232 converter such as a MAX232.
When BW pin is held high the TX output sends a single pulse, suitable
for low noise chaining. (no serial data).
[this is an ultrasonic sensor]

can this be connected directly to the RF transmitter?
i think i would still need a microcontroller on the other end
 
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