Problem in getting signal from RF MODULES

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laxman3018

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I AM working on a project called wireless metal detector
i have one pare of ht12e encoder and ht12d decoder and RF MODULES
when i am sending data from RF transmitter it properly sends the data to reciever...but
i want that when metal detector detects the metal one one signal shuld be send through RF transmitter so that other reciever side i recieved that signal and do something for indication like led glow...i have attached the metal detector circuit diagram i am using.....i have checked that when it detects metal 555ic pin 3 goes high and low high and low.....i tried to connect that pin with encoder but from there i am not getting any signal to reciever....how to do that help me plss..i am noob in electronics.....
 
The first transistor is a high frequency Hartley oscillator. Its output is rectified which turns on the transistor.
The turned on transistor continuously resets the 555 so the LED and the buzzer do nothing.
 
audioguru said:
The first transistor is a high frequency Hartley oscillator. Its output is rectified which turns on the transistor.
The turned on transistor continuously resets the 555 so the LED and the buzzer do nothing.
Click to expand...
yes this circuit is working..i want it to make wireless i have RF modules and encoder decoder...i want that when metal detects then i get singal like let glows on reciever side....
like image attached
 

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The schematic you posted does not light the LED and does not sound the buzzer. The LED will blink and the buzzer will beep only when something stops the high frequency oscillator.
Metal near the coil will change the frequency of the oscillator but will not stop it.

The Holtec encoder usually uses pushbuttons to send different codes. The schematic you posted does nothing and does not push a button.
Why do you want codes?
 
1) You must use a metal detector circuit that pushes a button on the HT12E encoder circuit when it detects metal.
2) The HT12E encoder sends data. Your RF transmitter should have a datasheet that shows how to make it transmit the data.
3) The datasheet for the RF receiver should show how to make it output the data it receives.
4) The datasheet of the HT12D decoder should show how to make it light an LED and sound a buzzer when it receives data.

You did not answer me. Why do you want data codes?
 
do you know how to push button on HT12E encoder by metal detector????
once i tried like this only tries to send some thing...i conected 5v to one pin of encoder and on decoder side i connected one led with resistor and when i turned on the device...there was one button given in encoder i pressed it and the led glows....and when i connected 0v to encoder and pressed the button again the led goes off..i was thinking to get some current from metal detector and give it to encoder like this...i m really blank now now what to do... how to make it work now..
 
i asked with one of my friend in college he told me about this...
Take pin 3 from
metal detector, give to base of transistor with 10k resistor. emitter
is grounded. connect RF trasmitter pin to collector. then collector
is connected to 5v with a 10k resistor.

but i didnt get this....
 

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You do not need an encoder and a decoder. They use data codes that you do not need.
You just want the metal detector to detect metal and turn on the transmitter then the receiver activates the LED and buzzer.

But you do not have a metal detector circuit that works.
 
laxman3018 said:
i have one metal detector .....its working when it detects metal.....ho do i connect rf transmetter???
Click to expand...
How can the circuit you posted work? Are you talking about a different metal detector circuit?

I explained that the oscillator always oscillates and the rectified signal turns on the transistor that turns off the 555 then nothing happens when metal is near the coil.
When metal is near the coil then the oscillator frequency changes a little but the circuit does not detect the change of frequency.
 
no no same one ....i got it what u told....no thinking what to do now...got into trouble..its my college project already name is submitted and demo is on 24th and its not working
 
The 555 is the tone generator. When pin 4 (RST) is held low there is no tone and when pin 4 is allowed to go high through the pullup resistor there is tone. So that determines when there is metal detection or not. Pin 4 High metal, pin 4 low no metal. The encoder has a /TE (Transmit Enable) so you should be able to work from there. You say it works so if the circuit works then pin 4 of the 555 OSC is the ball game point.

Measure pin 4 of the 555 and see if it does what I mentioned?

Ron
 
"i got it what u told" Very bad English. I do not know what it means.

Your project is a mess:
1) You have a metal detector circuit that does not work.
2) You have a data code encoder and decoder pair that you do not need.
3) You have an RF transmitter and receiver that you do not know how to connect.

How am I supposed to know how to make your RF transmitter and receiver work when you did not post their datasheets?
 
RF MODULE datasheet

and it means that what you have told about oscillator part of metal detector that part i have understand...
sorry for the bad english...
 

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iF i connect that pin 4 to my TE pin of encoder will it work????
 
No Ron.
The 555 uses a HUGE 100uF timing capacitor so it turns on and off at a few Hz. The buzzer makes the tone.
But the metal detector transistor continuously oscillates and holds the 555 always turned off.

A metal detector is supposed to detect the frequency change when metal gets near the coil. This circuit does not detect a frequency change.
 
laxman3018 said:
RF MODULE datasheet

and it means that what you have told about oscillator part of metal detector that part i have understand...
sorry for the bad english...
Click to expand...
Does the metal detector work or not work? Please say, "Yes it works" or "No it does not work".
The datasheet for the RF Tx and Rx shows exactly how to connect them.
 
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