26 replies to this topic

[Deerslyr]

Just got my stir plate finished yesterday. Had some problems with some connections. I get a nice vortex in water like the ones in your pics. I've got some stuff coming up which is preventing me from brewing until November at the earliest... possibly longer. Will just have to wait and see. I just transfered my lager yesterday. Was nice and clear.

[shmgeggie]

Edit: I like Dan Jeska's design a lot. It deals with 2 shortcomings of most home-built units: 1. Isolating the magnets from the fan with a PVC spacer.. and 2. A variable power supply driving the fan.

I have a dumb question to ask about the schematic. At the bottom, just under the 2K ohm potentiometer, there's a symbol for a ground. Is that just a reference to show how to orient the pot or is there an actual ground connection that you make there? All you have is +/- from the power-supply, so the ground symbol is confusing me (I am not an electronics expert, by any stretch of the imagination).

[Cliff Claven]

I believe the ground is a misprint.Try this from zymont's posting at the previous board.My link

[jimdkc]

No... not a misprint... Grounding the common side of your power supply circuit is not uncommon in electronics. It references your power supply to ground. If your stirplate is in a metal chassis, you would want to ground that too. If your stirplate is in an electrically insulated case (plastic, wood, etc.) it probably doesn't matter as much. Jim

Edited by jimdkc, 11 November 2010 - 02:19 PM.

[zymot]

The ground symbol is used more as a circuit common.You can bring the power supply minus, the minus lead of the capacitor, the lead on the potentiometer and the fan minus all to a single convenient point.IMHO, I would not ground the 12 VDC circuit. If you can isolate the positive and the negative, you will be better off.A word of warning. The metal tab on the LM317T is "hot." The regulator output is on the tab. When you mount the regulator, keep in mind anything that touches that tab, like a mounting screw will have the output on it. Do what you can to isolate the tab.12 VDC is not a safety issue, but it can be a problem if you short the output to something.When I built my stir plates, I sprung for the extra $.89 and put a heatsink on the regulator.

[shmgeggie]

It may not be able to electrocute you but 12V DC can get hot enough to start a fire, so it's still plenty dangerous. Thanks for the help.

[jimdkc]

If you're powering your plate with a wall wart type power supply, you probably don't even have a ground to connect! As zymot said... it pretty much means "common".Jim