Optima Plus 2 & Relay

[james.wilson]

you need a t-relay, there is only a few m/A available on that output and as lawandorder says its a logic output not a power output.

[lawandorder]

you need a t-relay, there is only a few m/A available on that output and as lawandorder says its a logic output not a power output.

I agree, if you are concerned at this voltage drop and and frankly I wouldn't be unless it's significantly affecting the output voltage at the aux output I would use a transitorised relay.

They generally have 3 inputs (12v, 0v and trigger), connect the + & - across aux and the trigger to the set output.

A standard, non transistorised relay will usually have a coil resistance of approximately 185 ohms (which is why I asked what yours read). The maximum current this could draw from a 13.5 volt output is less than 8 ma.

I don't have a manual for an Optima 2 Plus but the set output on other Optima panels will source 50 ma.

I agree, if you are concerned at this voltage drop and and frankly I wouldn't be unless it's significantly affecting the output voltage at the aux output I would use a transitorised relay.

They generally have 3 inputs (12v, 0v and trigger), connect the + & - across aux and the trigger to the set output.

A standard, non transistorised relay will usually have a coil resistance of approximately 185 ohms (which is why I asked what yours read). The maximum current this could draw from a 13.5 volt output is less than 80 ma.

I don't have a manual for an Optima 2 Plus but the set output on other Optima panels will sink 50 ma.

[Rulland]

I make that 73mA!

13.5/185 = 0.0729, 0.0729x1000 = 73

OHHHHhhh man you spotted it!, This is the sort.

http://www.tk-consultants.co.uk/JHLRT.html

[lawandorder]

I make that 73mA!

13.5/185 = 0.0729, 0.0729x1000 = 73

Yes, which is less than 80ma! lol

I was being deliberately "approximate" because we don't actually know what the output voltage is (though I guess it is about 13.5 volts).

To the OP, the 12 volt version of this relay http://www.maplin.co.uk/Module.aspx?ModuleNo=37494 has a coil resistance of 720 ohms so it would only draw 18.75 ma which is well within the rating of the output.

Much simpler than adding a power supply (which I don't think would work anyway)

[Amps]

As it turned out i didn't need to use the output afterall as the customer changed their requirements all's well that ends well and thanks for the help.

[Guest RJBsec]

As it turned out i didn't need to use the output afterall as the customer changed their requirements all's well that ends well and thanks for the help.

[Rulland]

Makes a change for people to say thanks-you'd be suprised how many get probs sorted etc and forget common courtesy! -Your welcome.

[Guest old-hand]

Much simpler than adding a power supply (which I don't think would work anyway)

Why not?

We fit additional PSU`s all the time to stop things being dragged down.

[lawandorder]

Why not?

We fit additional PSU`s all the time to stop things being dragged down.

Yes but where? I'm not being deliberately argumentative but consider the the following problem, you have a dual-tec which is several hundred metres from the control unit, the length and hence resistance of the cable is causing voltage drop at the detector.

If you fit an additional PSU adjacent to the panel the problem won't go away, the voltage drop will be identical, only by putting the PSU closer to the detector will the problem be solved.

Now, in the OP's case, the voltage drop is being caused by the resistor (onboard the PCB) coupled with the load of the ralay.

The only way an additional power supply could prevent this voltage drop is by wiring in parallel with the + supply and the latch output, obviously this would result in the latched output being at permanently - potential which means the realy would be permantly energised.

[Guest old-hand]

Yes but where? I'm not being deliberately argumentative but consider the the following problem, you have a dual-tec which is several hundred metres from the control unit, the length and hence resistance of the cable is causing voltage drop at the detector.Not the problem here

If you fit an additional PSU adjacent to the panel the problem won't go away, the voltage drop will be identical, only by putting the PSU closer to the detector will the problem be solved.

Again not the problem

Now, in the OP's case, the voltage drop is being caused by the resistor (onboard the PCB) coupled with the load of the ralay.

The answer being?

The only way an additional power supply could prevent this voltage drop is by wiring in parallel with the + supply and the latch output, obviously this would result in the latched output being at permanently - potential which means the realy would be permantly energised.

You need to go back to basics, and look at a circuit with relays, isolated from source.