Re: Interconnecting Smoke Alarms, And Capacitive Coupling ?

Bob,

Some smoke detectors operate on two wire systems and some on four wire
systems. The difference between the two is that one type needs to be
powered to operate. Therefore, if you have a four wire system, two
wires are to power your smokes. Now, smoke detectors as well as burg.
detectors use wire color codes as in DC to low voltage systems which is
different than house wiring color codes. So your red wire is power and
your black is ground. That leaves the other two wires. I'm sure that
instructions came with your smokes and that you wired your smokes
correctly. So this is not the problem. What you don't know is that your
smokes operate on resistance which controls the amount of current
passing through them. The old smokes operated on a different resistance
than your new ones and when you hooked them up and powered them they
all did their stuff. What you have to do is determine the current
difference between the two smokes. If the specifications are not
written on the old smokes than you have to place one of them into the
circuit and using a multimeter measure the current through the device.
If you don't have a current reading on your meter you can place a 1 ohm
resister in series with the smoke and measure the voltage across it.
The voltage will equil the current. Make sure that you pick a resistor
that is rated for the wattage of the circuit. Then all you have to do
is determine the current difference between the two smokes.If he new
smokes pass less current than you have to add some value of resistance
in series with the smokes and if they pass more current than you have
to place some resistance in parallel with the smokes. You see the
circuit has to see some constant resistance in order for it to
determine that all is right. When smoke enters the detector the
resistance changes within the decector and more current is allowed to
pass causing the alarm to sound. The resistors you choose have to be
determined by the series, parallel resistance equations. I really hope
that I have explained clearly enough for you to understand. Please
excuse my spelling.

Paul

.

Relevant Pages

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