Hi folks
I have bought a 12VDC car horn for an alarm system.I have used a 12VDC transformer +full wave rectifier to reduce/convert the 220VAC to 12VDC.
When i turn the system on,the alarm is almost inaudible.The 60db horn cannot be heard 2 meters away .But when i flick the - ,+ wires gently at their contacts,it blares loudly.But when i solder the same -and+wires firmly in place it is almost inaudible.
Why?
Hi the amps of the car horn is not stated.The output of the transformer is 2000mA.Output is DC not AC.I have a filter capacitor which is working.
I am using what is popularily called flexible cabble in local palance.Could that be a cause?Or i should try a much thinner wire?
I'm quite sure gerty is correct. When you momentarily make a connection by flicking the wire, the horn sounds loudly since the capacitor is supplying the high current the horn requires but can only supply it for a short time before it is discharged.
If you don't know how much current the horn requires, hook it up to a car battery with a multimeter in series set to measure current.
According to wikipaedia https://en.wikipedia.org/wiki/Vehicle_horn , most automobile horns use between 5-6Amps of current which is way above my transformer's capability.
I am considering may be using a motor cycle horn which consumes 1-2Amps.
THANKS
Does the alarm tone need to be a steady one? If not just use a piezo siren, which can be very loud indeed. some are over 110dB at 12v and only 100mA or so, well within spec of your transformer.