12v relay to up voltage
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12v relay to up voltage
Have an old type alarm fitted (moss) which used to activate the indicators when armed and disarmed. Connections are ok and other elements of the alarm work ok. I have checked the voltage when arming and the output from the unit fluctuates around 7 - 8v but does not switch the indicators on and off, I have also tested with a bulb which does not light up when armed. If I use a 12v 30 amp relay into the system will this create the extra voltage to flash the indicators. Posting this before testing as do not want to cause any damage.
1984 Campervan 1.9DG Petrol WBX
- marlinowner
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Re: 12v relay to up voltage
Use the alarm to energise the relay which then flashes the lights?
Won't do any harm but might not work depending on what's wrong with the alarm.
Won't do any harm but might not work depending on what's wrong with the alarm.
1993 SA VW T25/T3 2.5i Microbus/homebrew camper
1981/1968 Marlin Kitcar TR6 Engine
1981/1968 Marlin Kitcar TR6 Engine
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Re: 12v relay to up voltage
Yes thanks that's what I'm hoping, hopefully the voltage from the unit will be enough to energise the relay and flash the lights.
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- bigherb
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Re: 12v relay to up voltage
You would need a 6V relays. 12V relays struggle to pull in at around 7V although they will hold in down to around 5V. If you are switching the indicators you will need two relays one to switch each side, or a single relay and wire each side through diodes.
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- Oldiebut goodie
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Re: 12v relay to up voltage
Just use a step-up converter on the output from the alarm. But if you have isolated the indicators and then tested the output with a single bulb and the bulb didn't work there will not be enough current to do anything with and you will need to repair the output of the alarm. (or replace it )
Presumably you have checked the earths for the alarm haven't gone high resistance.
Presumably you have checked the earths for the alarm haven't gone high resistance.
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- marlinowner
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Re: 12v relay to up voltage
My thinking is its dropping 5v when connected to a bulb, a relay will draw circa one tenth the current of the bulb if the bulb is e.g. 21w, so may only drop a half volt or so - so relay may work OK.
1993 SA VW T25/T3 2.5i Microbus/homebrew camper
1981/1968 Marlin Kitcar TR6 Engine
1981/1968 Marlin Kitcar TR6 Engine