Electrical Increasing current in an intercom circuit

  • Thread starter mpulis
  • Start date
4
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Summary
I have an intercom circuit with a pre-purchased lock. The intercom is rated at 1.2Amps while the lock needs 2Amps. How can I make them compatible?
Hi,

I have purchased an electric lock some months ago. Now I purchased an intercom system which is rated at 1.2Amps. The cabling is rated at 1Amp. The lock is working sporadically. I guess it is because of the current.

Is it possible that I boost the current received? Maybe through a relay? So basically power the lock with a 12V 2Amps DC transformer and use a 2Amp+ (AWG 18) cable while I send the power signal from the intercom to a relay switch?

Or it would be best to use a diode of sorts to increase the current?

As you might realise, I am quite a newbie in electronics, so please do spell out things for me, even at the risk of belittling me :)

Thanks beforehand

PS: My model is the 520
 

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jrmichler

Science Advisor
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You need a relay fed by a separate power supply. A relay is a good idea even if the lock had the same rated current as the intercom. Just make sure that the power to the lock is correct for the lock. If the lock needs 12 volts, it gets 12 volts. If the lock needs AC (or DC), it needs AC (or DC). There is a huge difference between AC and DC when powering relay coils and locks.

No belittling implied. You recognized the problem and solution, and just needed some reassurance from somebody with more experience.

A diode will not increase the current.
 
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Thanks for your reply and reassurance!

This is how I intend to wire everything.

The DC adapter for the relay and lock is actually a 30A adapter with 10A buffer over the 80% capacity so it can spare the extra 2A.

Much appreciated

IMG-20190925-WA0000.jpeg
 
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Tom.G

Science Advisor
2,782
1,567
That means that the -ve from the power adapter goes straight to the lock right?
Right!

You stated that the lock operation is intermittent. In my experience of living and working in several buildings with electric door latches (locks), the usual cause of intermittency is wear or misalignment of the lock and/or the latch on the door.

The mating surfaces either get rough or have a groove worn in them so the lock can not release. The quick fix has been to replace the one with the obvious wear. This of course allows the remaining rough one to grind down the new piece, soon triggering another service call. If wear becomes a problem, replace both pieces!

Another problem, that depends on the lock/latch details, is weather stripping may apply enough opening force to the door that the lock cannot retract. Remount the lock so the weather stripping in not compressed so much.

Have Fun!
Tom

irrelevant recollection:
One building I lived in had a lock that worked fine in fair weather. After a rain it would not release. One time the manager was coming in as I was leaving... well trying to come in anyhow, it had rained the previous day. She complained about the lock and I said "That's an easy fix"... Here try it now.

When she asked what I did, I mentioned the rain and explained that most people have excess oil on their face next to their nose. I rubbed my finger next to my nose and transferred a little lubrication to the lock. She was still sputtering as I walked away.
 
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Thanks Tom.

But this is a brand new lock so one would hope there is no wear and tear already ;)

When I tried it with a 30A power adapter, it opened without any issue so it really seems to be an issue with current. Hence why the relay should fix the issue.

Thanks both for your help!
 

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