Having problem with wireless transmitter!

speed23947

New Member
I'm building a wireless IR sensor for a alarm to let me know when granny's on the loose at night. I wanted to use a 4 channel push button remote and receiver that i hadWIN_20141021_001648.JPG.
I hooked the receiver to a 8 pin picaxe and coded the alarm side. Thats working great, if you push the button on the remote the receiver sets the alarm perfect. the issue im having is with the transmitter side. Im useing a RHH HC-SR501 Adjust IR Pyroelectric Infrared PIR Motion Sensor.View attachment 17292 Thats working great to. the issue is the IR has a +3.3v output pin. I cant figure out how trigger one button on the remote with the 3.3v output of the IR. even if i added a picaxe on the transmitter side to use the 3.3v and switch something else. that's still wont help. I added the schematic of the transmitter chip and the buttons look like there in a resistor bridge of some sort. really not sure how to trigger it. All i need is a 1 sec pulse from the IR the set off the alarm. anyone have any thoughts?
 

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geoff07

Senior Member
If you can intercept the button connections on the remote then you can use e.g. a reed relay or maybe an opto-isolator to trigger the remote. If you can do that then you can control the relay or opto-isolator using a picaxe (or even perhaps a transistor) triggered by the 3.3v signal. But I didn't quite understand your comment 'that's still wont help' so may have misunderstood.
 

SAborn

Senior Member
I fail to see the problem here, as the picaxe should trigger a high input signal from anything above 2.5 volts, or simply do a ADC reading of the input and look for a value higher than the static reading from the IR sensor.

As long as your sensor and the picaxe has a common ground (V-) then the circuit should work.

Are you sure the sensor is rated to 3.3v as all the ones i have used are 5v rated.
 

speed23947

New Member
There is no picaxe on the transmitter side. Just the infrared and the transmitter. I'm trying to get the switched leg of the IR (when tripped) to turn on one of the buttons on the transmitter . Just as long as the IR is tripped.
That's long enough to set the alarm(receiver side). My issue i'm having, if you look at the datasheet of the transmitter, is that it looks like there using a resistor bridge to pull down the switches. I'm not sure how to deal with that.
A reed relay could short the switch as if is was getting pushed but the output of the IR is only 3.3v and very little current. not enough to run a coil. I was hoping not to have to add another picaxe on the transmitter
side but i dont see how with out one.
 

hippy

Technical Support
Staff member
My issue i'm having, if you look at the datasheet of the transmitter, is that it looks like there using a resistor bridge to pull down the switches. I'm not sure how to deal with that.
The component on the far right of the circuit, though not immediately clear, is the battery with +Ve at the top. The diodes simply allow the battery voltage to power the transmitter and chip when any button is pushed. The vertical resistors allow the chip to determine which button was pushed and, I would guess, the horizontal resistors simply keep those inputs not pushed at 0V.

If the PIR output goes high it may be possible to take that to the left side of one of the buttons to effect the same as having pressed a button and completed the circuit. Remove the battery to the transmitter if you do that. Success will greatly depend on if the PIR can supply enough current to power the transmitter and transmitter chip.

It's not clear how you are powering your PIR or the transmitter module so an explanation in that respect may help.
 

sghioto

Senior Member
Could add a transistor switch as shown on this edited version of the schematic. Connect the collector of Q1 to the diode side of the switch you prefer. The 3.3 volt IR output should be able to power this arrangement.

Steve G
 

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