I failed. It was awesome.
Based on a true story...
Recently, I set out on a quest to install a new intercom. I had this ooooold Commax CDV-43K which I could have spent hours tinkering with to get it IOT-ified, OR;
I could just buy one that already has the capabilities built in, and maybe make some money back reselling it.
I did the latter, settling on a Hikvision DS-KIS313-P.
Off the bat, we get the following features out of the box:
- Remote door unlocking
- Remote monitoring
- Visitor tracking
- Relatively easy setup*
- Integration into my existing network and security systems
I say “relatively” easy setup because it’s a 4-wire intercom. A bit of marketing is involved with intercoms systems advertising “2-wire” systems being easier, which isn’t a lie - connecting 2 wires is definitely easier than 4.
What I didn’t realise here is that the more wires you work with, the more potential points of failure you have. And I needed 2 extra wires for the power supply of my elecromagnetic door log.
Installation was simple, or was it?
I didn’t have any gripes with the installation. It’s literally mounting the intercom or “door station” as they’re referred to, and the monitor, and wiring them up.
The first problem I had though, was my previous contractors that removed my intercom cut the existing cable that I could have reused from the old intercom.
No worries, I just got another cable from Builders Warehouse, and wired them together to avoid ripping out the existing wire that was mounted in the wall.
This didn’t solve a couple issues I was still experiencing though…
A crash course in electronics
Electomagnetic locks are interesting, fickle devices. Relays as well, and together in a circuit, they’re like 2 Daschunds in a ballpit.
Relays (like the one in my door station) can reduce the current flowing in a circuit. Electromagnetic door locks require current to activate. When you have a power supply that supplies just enough current and voltage for the lock to open under reasonable conditions…
…You get where I’m going with this?
Under load with my setup, my current and voltage dropped significantly. And being a persistant bugger, I got my multimeter out and spent a few evenings (to my wifes disapproval) figuring this out before getting a professional involved.
I narrowed the issue down to the following:
- There was an insufficiently connected wire in the roof, where the existing wire was cut.
Possible, though I did ensure the connections were twisted sufficiently, and was one step away from soldering those connections, but I really didn’t feel it was necessary.
- One of the wires from the powersupply wasn’t suitable.
By this, I mean it wasn’t the right AWG/gauge, which could have caused unnecesary resistance in my circuit. One thing I forgot to mention is the wire between my monitor and door station is a good 14 meters long, so any influence on resistance would affect the connection.
- The door station relay was sucking my circuit dry.
Which is frankly quite rude. The way around this was to install a separate relay, and treat the connection from the door station as a signal, which activates a secondary relay giving raw power to the lock.
So what was the solution?
I’m still waiting for the security team assessing the setup to finish, so I’ll update this as soon as they’re done!
Edit It was the powersupply. My wiring was correct, I greased the lock sufficiently, contacts were clean without corrosion…
The power supply was just on its way out.
I’m going to go get a coffee.