Nc Reed Relay Not Triggering Alarm When Opening

[hpotter]

The circuit dgm you posted explains well, how to control the relay with a transistor. I was thinking you might of been using a power xistor and assumed you are using the same power source for the two relays the contacts of one controlling the other. hense the leakage thoughts.

Still struggling to get my head round what youre attempting to achieve tbo.

Hair of the dog, me thinks

Are they open yet?

[luggsey]

Don't forget there is a "signal" of some sort on the wireless door switch, it may be sensitive to external influences with wires connected externally or the signal may be very small and capacitance in your cables holding it back as it were?

The signal designed to go through a tiny reed switch may need to be lifted in the door switch, the signal is kept as low as possible to save battery life in the unit. Try the relay right next to the wireless switch with very short leads.

[wbrells]

The circuit dgm you posted explains well, how to control the relay with a transistor. I was thinking you might of been using a power xistor and assumed you are using the same power source for the two relays the contacts of one controlling the other. hense the leakage thoughts.

Still struggling to get my head round what youre attempting to achieve tbo.

I'm currently using the circuit with the 555 chip rather than the one with the transistor. The basic idea is to have a smoke sensor activate an external relay so that I can: (1) Trigger the SkyLink alarm console and/or (2) Trigger an X-10 Powerflash unit which I'll use to sound remote sirens.

Hair of the dog, me thinks

Are they open yet?

[lawandorder]

Ha got it now, sorry OP I was confusing your objectives with an entirely seperate thread!

I have looked at the circuit diagram and to be honest it should work.

If you study the diagram the contacts of the relay (RLY 3) are electrically isolated from the power supply and that is just how it should be. I suspect that there is some leakage between the coil of the relay and it's contacts in your case (perhaps a splash of solder), check for continuity between the contacts and the coil connections.

Are you using the "power cube" to power the radio transmitter and the relay circuit?

Something is causing a current path between the transmitter and the relay circuit so I can only assume that there is leakage somewhere.

[wbrells]

Ha got it now, sorry OP I was confusing your objectives with an entirely seperate thread!

I have looked at the circuit diagram and to be honest it should work.

If you study the diagram the contacts of the relay (RLY 3) are electrically isolated from the power supply and that is just how it should be. I suspect that there is some leakage between the coil of the relay and it's contacts in your case (perhaps a splash of solder), check for continuity between the contacts and the coil connections.

Are you using the "power cube" to power the radio transmitter and the relay circuit?

Something is causing a current path between the transmitter and the relay circuit so I can only assume that there is leakage somewhere.

After much "head scratching" I'm beginning to believe that there may be enough capacitive coupling between the relay contacts and the relay coil to detune the transmitter in the wireless door sensor. In other words, the door sensor may, indeed, be triggering but at a slightly incorrect frequency that is not being recognized by the SkyLink alarm console. I realize that reed relays with electrostatic shielding are available to drastically reduce this coupling problem, but unfortunately it doesn't seem very easy or inexpensive to get one of these "non standard" units... Can you suggest any EXTERNAL circuitry that might reduce this coupling problem? If not, do you know of any small, relatively available 5-or-12 volt NON-REED relays which operate on 50ma or less?

BTW, when the reed switch in the door sensor is closed, the current through it is approximately 3 microamperes. When opened via my external relay the current - as expected - drops to zero. Again, this suggests to me that some sort of unwanted capacitive coupling is the problem!

To answer your other question, the wireless door sensor unit is powered via a small CR2032 battery.

[luggsey]

You can easily check that by using a RF frequency probe, a scanner or a near field signal monitor.

In the UK security devices use spread spectrum which is not easily detected but the one you have may be a fixed frequency.

You can always fit a low signal transistor in the wireless switch to overcome this?

[lawandorder]

After much "head scratching" I'm beginning to believe that there may be enough capacitive coupling between the relay contacts and the relay coil to detune the transmitter in the wireless door sensor. In other words, the door sensor may, indeed, be triggering but at a slightly incorrect frequency that is not being recognized by the SkyLink alarm console. I realize that reed relays with electrostatic shielding are available to drastically reduce this coupling problem, but unfortunately it doesn't seem very easy or inexpensive to get one of these "non standard" units... Can you suggest any EXTERNAL circuitry that might reduce this coupling problem? If not, do you know of any small, relatively available 5-or-12 volt NON-REED relays which operate on 50ma or less?

BTW, when the reed switch in the door sensor is closed, the current through it is approximately 3 microamperes. When opened via my external relay the current - as expected - drops to zero. Again, this suggests to me that some sort of unwanted capacitive coupling is the problem!

To answer your other question, the wireless door sensor unit is powered via a small CR2032 battery.

It is possible that your problem is being caused by unwanted coupling, either inductive or capacitive but I would imagine that a likely source of any problems is the power supply you are using. (the power cube).

Dc current cannot be induced and neither can it be coupled capacitively but if there is low level AC on the power supply which in fariness is very likely in a low cost power supply this could be the problem.

The 555 timer you are using can be configured as an astable which would cause an AC current to flow but this is not the case in the circuit diagram you have shown so the only source of AC can really only come from the power supply.

Try powering your relay circuit from a battery as a temporary measure.

[wbrells]

It is possible that your problem is being caused by unwanted coupling, either inductive or capacitive but I would imagine that a likely source of any problems is the power supply you are using. (the power cube).

Dc current cannot be induced and neither can it be coupled capacitively but if there is low level AC on the power supply which in fariness is very likely in a low cost power supply this could be the problem.

The 555 timer you are using can be configured as an astable which would cause an AC current to flow but this is not the case in the circuit diagram you have shown so the only source of AC can really only come from the power supply.

Try powering your relay circuit from a battery as a temporary measure.

Well, I tried powering my circuit with a battery & with the power "cube" totally disconnected. Unfortunately the door sensor still does not trigger the alarm console when the external relay is energized to open the NC contracts. In other words, the problem is exactly the same! I'm going to look for a different (non-reed) relay and see if that works any better... I'll keep you posted!

[luggsey]

Well, I tried powering my circuit with a battery & with the power "cube" totally disconnected. Unfortunately the door sensor still does not trigger the alarm console when the external relay is energized to open the NC contracts. In other words, the problem is exactly the same! I'm going to look for a different (non-reed) relay and see if that works any better... I'll keep you posted!

So stick a switching transistor in the door switch?

[Alarm Co]

is it the same as a scantronic radio door contact

you can hard wire a read switch to it but you have to move jumper

on board to enable operation

??