The LEDs (and 1.2k resistors) were placed after the diodes; 1 to show the circuit had power and the other to show there was power supplied from the sensor etc. It all worked perfectly at home,

When connected to the controller were both LEDs ON when the sensor was not activated?

 

I'm not clear as to which circuit you have built. (The second circuit in post #3 or the one in post #14.)
If it was the one in post #14 then add a pullup resistor (Say 10K ohms.) from the left hand end of resistor R1 to +24 volts. Also remove the +24 volts connection the the NC contact on the relay. (Alternativly you could remove the relay an just connect the input of the controller to the junction of Q2 and Q3.

Les.

 

I think this is the circuit in question with the added diodes and LEDs.
I don't remember all the exact component values though. Will need confirmation from Sdsaibot.

 

Hi, sghioto. I think with the circuit in post #23 just adding a 1K2 resistor between the lefthand end of D1 and +24V should make it work.
Les.

 

True if the sensor output is truly open when not activated. D1 would need to removed as well.

 

What is missing to adequately describe how the circuit works is to lose that ground symbol and add the connections to the 24 volts common and the sensor common. And possibly the controller common if it is separate from the 24 volts source.

AND I certainly hope that the 24 volts is DC!

 

Hello,

Thanks for the info sghioto and LesJones.

I am very pleased to say the suggested changes worked like a charm!! I installed the circuit yesterday when at my parent's place, and the sensors will only activate if they are triggered for approx. a second. You can walk through them and the gates don't open (which is fantastic), but a car driving through them will make them open!! Perfect!!!

Using A/CAD I have tried to draw the final circuit diagram, hope I have got it correct... As I didn't want to take up more of anyone's time, with further questions, I have added in a couple of extra items myself, which surprisingly seem to also work!! They include:
- a switch to select the time the sensors need to be triggered for, before activating. This is achieved by having 2 alternate capacitors in the circuit, and a SPDT switch.
- an external switch, which, when pressed, will open the gates. Basically just a rocker switch, mounted on the outside of the gates.

The reasoning for the additional items is due to the fact my parents are in their late 70s, and I want to make sure they are kept in the safest environment possible. That is, to make sure the gates don't continually open (allowing anyone driving past to enter the property), as well as providing a way for emergency services to enter the property if needed (the external switch can only be accessed by way of a key, which all the emergency services have).

Although they may not be the best way of integrating the items, I am pretty happy they all seem to work!! hahahaha.

Once again I would like to thank everyone for their assistance, as it is something which definitely could not have been achieved without other's expertise!! You should be proud of yourselves, for you have taken the time to help a person you don't even know. As my Father would say, "you are a gentleman and a scholar".

 

Great, glad it's working. Those mods look fine to me.
Good job on that.
Thanks for getting back to us as well.
We don't see that very often on the Forum.

 

OK, that is a GOOD drawing!
But it is not clear that the emergency switch is in the correct location, since it appears to disconnect the sensor signal.
And the timer scheme looks a whole lot like what I was suggesting, but it uses less power, so that is an improvement.

 

When the emergency switch is open the 2N3904 will not conduct so it's collector will be pulled high by the 1M resistor. When the capacitor has charged to a high enough voltage for the mosfet to conduct the mosfet drain will go low causing the gate to open. One point though, if the wire between the switch and the 1M resistor is long it could pick up electrical noise and cause the gate to close again. If you do see this happening I suggest adding a resitor between the left hand end of the 1M resistor (Say 10K to 100K ) and ground so that the base of the 2N3904 is not floating when the switch is open.
I agree with MisterBill2 that it is a nice shematic.

Les.