This is the second post in a five part series on the updates made to my beer stand for the Jan 3rd brew. Here are links to the previous post:
Control Panel
The control panel itself has been mostly complete for months and has been waiting for me to find away to attach it to the stand, and decide upon how to best wire it to the stand. I will discuss all of these below, but first let me describe whats on the panel.
In the upper right is a power indicator LED and lighted toggle switch. The power indicator lights up when the stand has been given power. To turn the panel on the lighted toggle switch is pressed, at which time it will light up indicating power flow. Next, from top to bottom we have the water control row, HLT control row, and the mash/pump control row. The water control row currently only consists of a momentary switch that will toggle the water flow on and off. Eventually I envision there may be more of these for other valves, as well as a LED indicating when flow is occurring. The second row is for controlling the HLT heat. The toggle switch on the left determines how heat is applied. When the toggle is up, heat is applied only when the temperature controller to the right is triggered, otherwise it's off. When the toggle is down the gas is on. When the toggle is in the center position the gas is off. The LED to the right of the row indicates when the gas is on. The third row, which is used to control the mash heat and pump works the same way the second row did. The primary difference being that it controls whether the pump is on or off. This will be used to regulate the mash temperature by stopping the pump (and HERMS) when the mash is overheating and starting it when it is under heated.
Mount
I spent a decent amount of time trying to decide how to mount the panel to the stand in a way that was flexible and non-intrusive. I originally planned on a fixed location for the panel but really couldn't decide on the best way to do it. At some point I decided that the right side of the stand was the best out of way place even though this put it the furthest from all of the components. I began to draw up plans for a fixed mount when it dawned on me that maybe the panel could be mounted using a movable LCD stand with a desk mount. After some research I settled on a cheap LCD arm (Ergotron 45-174-300) that was simple but still somewhat flexible. I was able to get this from Amazon for only $66.
|
|
|
|
|
The second piece to the puzzle was mounting the panel to the LCD stand. I struggled with this for a while, trying to come up with a solution. Luckily I was able to find a standard VESA mount quick release designed for use with LCDs that is very durable and easy to use. The one that I got is made by HP, model number EM870AA. I purchased it from buy.com for $29.99, so all in all not a bad deal. You can see from the fourth picture above that to unlock the release you slide a metal tab to the right or left and the panel will slide out (picture 3 above). To secure the quick release mount I cut a piece of plywood up square that consumed around 75% of the back of the panel. I then positioned the quick release on the plywood, marked the holes, and drilled the holes into the plywood. I took a larger drill bit and took out 1/8 inch of wood around each drilled hole for the bolts to sit. The bolts could then go through the holes and sit flush with the back of the plywood. The holes with the bolt heads were then epoxied in place and the whole piece of plywood was epoxied to the back of the panel. After that it was just a matter of lining up the mount to the bolts and securing it with lock nuts.
In order to mount the arm to the stand I had to cut a notch out of the
side (picture 2 above), but this was easy enough to do. The clamp holds
very tightly and is more than enough to hold the arm and panel.
Wiring
Most of the changes to the panel occurred in the wiring. I originally had setup the panel to use a romex connector. If you look at the left picture below you can see it, it's a white thing in the middle left, thats the female connector. The romex connectors were just to flimsy and hard to deal with, so I went with using DC power plugs (size M from radio shack). These plugs are fairly tough, have decent holding power, and should be able to handle the 24 v current the stands components draw. I have one plug in the back for each main component of the system: HLT probe, mash probe, float switch, gas solenoid, and water solenoid. To mount these plugs I was originally using a small piece of aluminum, but quickly realized that by doing this all the connectors ran together. I narrowly caught this before shorting the whole panel. To fix the problem I replaced the panel with 1/8 inch Plexiglass. In addition to the DC plugs, I added another computer style IEC power plug for the pump. This line feeds back into the pump so that the panel can appropriately control it.
The internal wiring of the panel is a little more complex. At some point I may post on the specifics, but for now let me just give you the overview. The panel takes 120 v power in from one of the AC plugs on the back. This is used to power the LEDs, temperature controllers, pump, and a 24 volt transformer. The transformer is used to power the gas solenoid and water solenoid. In addition there are two relays inside. The left most relay is a 2-step sequencing relay which when triggered holds its state. When its triggered again it swaps state. This relay is used for the water solenoid so that the momentary switch can turn the water on and off. The float switch also ties into this relay to prevent overfill. The second relay is for activating the gas solenoid, which requires 24 volts. This is needed because 120 volts is used to power the temperature controller and LED. When the heat component gets triggered, either by the toggle switch or controller, the 120 volts is sent to the relay coil, which triggers the release of 24 volts to the gas solenoid. Thats about it really.
Next Brew Stand Update Post
Next post I will be going over the new Gas and Water components.
Experiences in Beer
Subscribe