I have a very simple circuit here, which waits about 5 seconds after an input goes low, then trips a relay to control something else. I have a 27MHz micro-power transmitter link which goes active when the relay closes, but at the very instant that the relay closes, the transmitter DOES activate, but the relay drops out again within about 200ms or so, yet it is supposed to stay closed for one second.
The code is beyond basic:
high 2
wait 1
low 2
That's it, but the relay is not staying active for the 1 second.
If I disconnect the relay contacts, so that the circuit operates, but does not trip the transmitter, the circuit works perfectly, and I have my 1 second "ON" delay. The second I reconnect the relay contacts, the relay drops out too soon, which is why I am wondering how the PIC is reacting to the 27MHz signal...
Relay contacts are clean - they are not directly(via the PCB) ground-referencing or tieing high, anthing connected to it. The transmitter itself runs directly from the 12v supply, and you ground the enable line to activate the transmitter, so I have done this via the relay contacts - connect the NO and COM lines from the relay across the transmitter's GND and EN lines.
PSU is regulated 12v @ 1.25A, regulated down to 5v for the PIC via 7805, with darlington transistor arrangement driving the relay from the 12v supply. The 12v input has a 470uF filter along with 100n, and there is also a 100n right beside the PICAXE to help filter off any noise in the PSU.
27MHz transmitter draws 40mA when transmitting - including a flashing red LED, so the actual transmitt power must be flea-powered.
So, I am wondering if the PICAXE, or any other PIC does not like 27MHz or for that matter, any other frequencies.
The code is beyond basic:
high 2
wait 1
low 2
That's it, but the relay is not staying active for the 1 second.
If I disconnect the relay contacts, so that the circuit operates, but does not trip the transmitter, the circuit works perfectly, and I have my 1 second "ON" delay. The second I reconnect the relay contacts, the relay drops out too soon, which is why I am wondering how the PIC is reacting to the 27MHz signal...
Relay contacts are clean - they are not directly(via the PCB) ground-referencing or tieing high, anthing connected to it. The transmitter itself runs directly from the 12v supply, and you ground the enable line to activate the transmitter, so I have done this via the relay contacts - connect the NO and COM lines from the relay across the transmitter's GND and EN lines.
PSU is regulated 12v @ 1.25A, regulated down to 5v for the PIC via 7805, with darlington transistor arrangement driving the relay from the 12v supply. The 12v input has a 470uF filter along with 100n, and there is also a 100n right beside the PICAXE to help filter off any noise in the PSU.
27MHz transmitter draws 40mA when transmitting - including a flashing red LED, so the actual transmitt power must be flea-powered.
So, I am wondering if the PICAXE, or any other PIC does not like 27MHz or for that matter, any other frequencies.
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