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Electronic Door Srikes
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FearNoIdea View Drop Down
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    Posted: 18 April 2006 at 6:38am
Ok, that clarifies it for me. Thanks. I like the idea of the box you are using for your RFID access.  Having a usb and molex port would make the unit look very nice, and self-contained.  I lack the ability to give up a pc for my door.  The reason I am using the standalone power source is due to the distance from my pc to my door.  I have to run cat5e across my house and into the Keyspan to connect the reader to my pc.  
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KyleB View Drop Down
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Well I might have more actual wires but its the same number of lines going to the box :). Instead of your power supply I've got power coming from the PC.

It started out as the easy way to power the device. I've got a test power supply that I use for various projects. Seeing as this has 5 and 12VDC I got the 8-16VAC/3-6VDC lock (I like options). I also have a PC that I'm going to put by my office door to monitor the lock so I figured this would be the easy way to power and control it. Once I started working on this I thought of making a more generic RFID box.  This box would contain the Phidgets board, have a USB port for control, pc molex power input and a power output connector that I could hook devices up to. I might throw on a switch to change between 5VDC and 12VDC output.  So this would give me a neat little hobby box to test RFID devices with. I could power up any 5-12VDC devices that I connect, etc...

 

k.
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amal View Drop Down
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Joined: 22 November 2005
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Originally posted by KyleB KyleB wrote:

The PC's 5VDC can supply 20-30amps and the lock "draws" 900mA? So the PC power supply is plenty for supporting power for the lock?


That's correct. 900mA is 0.9 amps. The PC power supply is capable of supplying 20-30 amps, so as long as no other devices are drawing (using) all available current, you should have enough to power your strike.

Originally posted by KyleB KyleB wrote:

Was there a specific rating on the diode to solder across the relay coil? I found a 200V 1A silicon diode at RadioShack. I've got no clue if its overkill or not enough...


You don't really need much of a diode, you can use a simple switching diode. The one you have is a little overkill, but it should work just fine.
Amal ;)
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FearNoIdea View Drop Down
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KyleB -
   I guess I am a little unclear here.  You are using a USB port to power and communicate with your phidgets reader then using one of your PC's free molex connections to power your lock via a relay triggered by your reader?  Is this correct?  If so, why are you doing this?  With my project I am trying to minimize the amount of wires, this seems like excess.

My electric strike is a Lee Electric: Mortise Electric Strike reversible
My power supply is a RadioShack model: 273-1773 12v 500mA power supply.
My relay is a RadioShack model: 275-240 5VDC 1A SPDT relay.

I will be using the Keyspan USB Server, currently in the mail, to serve the reader to my home network.  I am curious, is there a reason you went with the lower voltage strike? Is there a benefit you are gaining that I have overlooked?


Edited by FearNoIdea - 17 April 2006 at 8:37pm
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KyleB View Drop Down
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Sorry I wasn't clear. I don't want to run the lock off the Phidgets 5VDC just the PC power line 5VDC. 

I just want to clarify this since I'm not very familiar with some of this. The PC's 5VDC can supply 20-30amps and the lock "draws" 900mA? So the PC power supply is plenty for supporting power for the lock?

I've got a test power supply rigged up and I've wired up a relay off the Phidgets board and it works fine off the 5VDC. However I know a quick test and extended use are two entirely different things.

Another side question, was there a specific rating on the diode to solder across the relay coil? I found a 200V 1A silicon diode at RadioShack. I've got no clue if its overkill or not enough...

Thanks for the prompt reply!

k.

 
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amal View Drop Down
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Originally posted by KyleB KyleB wrote:

I picked up the smarthome 8-16VAC/3-6VDC version. Does anyone know if there are any problems powering this off of a 5VDC line from the computer? I want to wire up a box for the Phidgets board that uses the 5VDC line to power the lock.  I'm not sure about the 900mA that the lock description talks about and if this is compatible with the pc line.


I said this in an earlier post:

Originally posted by amal amal wrote:

Even though the thing is directly connected to the Phidgets, I don't suggest you do that. The current draw from the latch is too high and energizing it for longer than a second or two will result in that familiar burning smell. Even at a second or two I'm sure it severely limits the lifetime of the transistor on the Phidgets board.


The fact is, you CAN power a 900mA device from the USB port, but you should make you have no other USB devices on the entire USB bus. Typically, the max available current on a USB 1.1 or 2.0 bus is around 500mA max, but as you can see I've been able to power my strike.

As for powering your strike off the PC power supply, the +5V output typically can support between 20 and 30 amps. Not to be confused with the -5V output, which can really only supply about half an amp.

Here's a great reference for powering devices from your PC: http://www.epanorama.net/circuits/power_from_pc.html


Edited by amal - 17 April 2006 at 7:47pm
Amal ;)
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KyleB View Drop Down
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I picked up the smarthome 8-16VAC/3-6VDC version. Does anyone know if there are any problems powering this off of a 5VDC line from the computer? I want to wire up a box for the Phidgets board that uses the 5VDC line to power the lock.  I'm not sure about the 900mA that the lock description talks about and if this is compatible with the pc line.

 

Thanks,

k.
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FearNoIdea View Drop Down
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I have purchased the following electronic strike

12Vdc Electronic Strike

In all of my desk testing this unit is performing fine. I will update this post after I have installed the strike in my door frame.  I would like to note the mounting depth is significant.  One should take into consideration the depth of a strike like this when ordering.  Some fairly significant modification to my wood doorframe will be necessary to install this unit.
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amal View Drop Down
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Shoot... wrong movie. This one is the correct one (I also updated the previous post).
Amal ;)
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FearNoIdea View Drop Down
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Points: 13 		Post Options Post Options   Thanks (0) Thanks(0)   Quote FearNoIdea Quote  Post ReplyReply Direct Link To This Post Posted: 04 April 2006 at 5:01am
I like that these strikes are reversible.  I was alittle disappointed to see the shipping $10US for one of these little strikes.  For the moment I have only ordered 1 of them, for testing purposes.  I will let you guys know how it goes.

...

Hey Amal... That movie doesn't show a strike at all... It does show a nice little desk setup though. =)  I dig the monitor config.
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