Help me activate a relay from 2.4GHz receiver

[thebadtall]

Hello , I would like to use a channel of a 2.4GHz receiver , to turn on a relay.
The output signal of the receiver varies from 0.15v to 0.26v , depended on the position of the transmitter's knob.

Can I use a simple transistor to activate the relay when the signal hits 0.29v ?

Thank you

 

[chuckey]

A single transistor could be made to work but it would require very careful setting up and might not be temperature stable. Use an opamp.
Frank

 

[thebadtall]

I guess it gets complicated with opamp. Can I use it with single voltage or it needs +- power supply?
Any ideas about the gain that I need ?
I have 5- ne5532 lying around

 

[chuckey]

datasheet :- https://www.ti.com/lit/ds/symlink/ne5532.pdf It will work on a 0, +10V or more PSU. You split the PSU to give you a false 1/2 Voltage point ( 2 X 1K resistor). Now you feed this voltage into both the+ and - inputs via a 100K resistor to each. Now the opamp thinks its running on a +- supply. You feed the - input via a 100K from a .2V reference source (pot across the Vcc line). You feed your receiver into the + input via another 100k . Connect a low current relay between the Vcc and the amps output, with a diode across the coil (cathode to +Vcc).
Frank

 

[thebadtall]

Thank you. More headache tomorrow!

 

[dick_freebird]

For anything that might have, shall we say, negative
consequences to false firing you would want a higher
standard for actuation. Otherwise some other joker's
Bluetooth gizmo might leave you minus a hand.

Nobody uses CW detectors for anything safety critical.

But of course this is a simple and benign science project.
Right?

 

[thebadtall]

A friend bought a cheap rc boat. Rc doesn't work. I have a nice 6ch kit so will try to use it.
His boat got 2 motors so I just want to control each motor at 100% as I don't want to deal with speed controllers and stuff .....

I would like some reliability or the receiver wich costs as 3 boats will swim to Turkey

 

[thebadtall]

datasheet :- https://www.ti.com/lit/ds/symlink/ne5532.pdf It will work on a 0, +10V or more PSU. You split the PSU to give you a false 1/2 Voltage point ( 2 X 1K resistor). Now you feed this voltage into both the+ and - inputs via a 100K resistor to each. Now the opamp thinks its running on a +- supply. You feed the - input via a 100K from a .2V reference source (pot across the Vcc line). You feed your receiver into the + input via another 100k . Connect a low current relay between the Vcc and the amps output, with a diode across the coil (cathode to +Vcc).
Frank

thats what I understood, is it correct ?




++ I have a ULN2804. Can I use that Instead of the whole previous ?