Continuation of "TOKO Inductors Needed for EM Theremin"

Posted: 12/19/2007 11:08:03 AM
jluciani

From: Massachusetts

Joined: 8/18/2007

The problem with wood is the thickness. Check
the maximum panel thickness for the pots, switches and jacks. If the wood is too thick you would have to do counterbores for the panel components.

You could get try getting a thin plywood. If
you are going to paint the project look at
Baltic Birch for stained cabinet get a hardwood plywood.

Another option is lexan or acrylic.

(* jcl *)
Posted: 12/19/2007 11:24:10 AM
therem13

Joined: 9/25/2007

I think that some hardwood planed down to 1/8" should work with all the components.
Posted: 12/19/2007 1:24:23 PM
jluciani

From: Massachusetts

Joined: 8/18/2007

It could. I think you would be better off with
a hardwood plywood.

(* jcl *)
Posted: 12/19/2007 2:23:01 PM
therem13

Joined: 9/25/2007

On the schematic, the lines representing wires often cross. Are they to be electrically connected at all intersections, or just where there is a black dot where the wires cross?
Posted: 12/19/2007 2:27:51 PM
jluciani

From: Massachusetts

Joined: 8/18/2007

The dots represent connections. The crossed wires
are not connected.

(* jcl *)
Posted: 12/19/2007 2:35:28 PM
therem13

Joined: 9/25/2007

I think I'm finally understanding that all of the places with the earth ground symbol should all be connected to a common earth ground -now, it sounds painfully obvious, but there is some confusion ;)...

So, in the Hotrodding article, it's said that the Theremin needs to be connected to earth ground. In the DIY EM Theremin article, that is never stated, and I think that that schematic doesnt include any true earth grounds. Does this mean that the earth ground symbols in the DIY EM Theremin article refer to chassis grounds? If the EM Theremin does need to be connected to earth ground, should I just attach the earth ground symbols to earth ground (instead of chassis ground which was perhaps the meaning of the earth ground symbol in the DIY EM Theremin article)? I assume that if I interpret these symbols as a connection to a common earth ground, I don't need to worry about a chassis ground...??

Are the -12V and +12V symbols at the end of some of the wires in the schematic similar to the ground symbols in the sense that they all connect to -12V and +12V, respectively?

Thanks,
Dan
Posted: 12/21/2007 8:58:32 PM
therem13

Joined: 9/25/2007

I think my internet has been malfunctioning, so I'm not sure if this was posted when I intended to post it (there may be a duplicate). Here it is:

I think I'm finally understanding that all of the places with the earth ground symbol should all be connected to a common earth ground. -Now, it sounds painfully obvious, but there is some confusion ;)...

So, in the Hotrodding article, it's said that the Theremin needs to be connected to earth ground. In the DIY EM Theremin article, that is never stated, and I think that that schematic doesnt include any true earth grounds. Does this mean that the earth ground symbols in the DIY EM Theremin article refer to chassis grounds? If the EM Theremin does need to be connected to earth ground, should I just attach the earth ground symbols to earth ground (instead of chassis ground which was perhaps the meaning of the earth ground symbol in the DIY EM Theremin article)? I assume that if I interpret these symbols as a connection to a common earth ground, I don't need to worry about a chassis ground...??

Are the -12V and +12V symbols at the end of some of the wires in the schematic similar to the ground symbols in the sense that they all connect to -12V and +12V, respectively?

Thanks,
Dan
Posted: 1/17/2008 5:59:08 PM
therem13

Joined: 9/25/2007

I've talked a little with an electrical engineer, and he said that If I use the Theremin with an amplifier that would ground it adequately, and if I had another ground that could create a ground loop and create hum. Is he correct about this? I'm not sure if I'd always use the Theremin with and amp, so it would be nice to have the other ground, but I don't want that to be a problem for when I use an amp.

Thanks,
Dan
Posted: 1/17/2008 7:16:47 PM
Thierry

From: Colmar, France

Joined: 12/31/2007

He is right about the hum risk when double-grounding.

That's why I suggest to drill an additional hole in your theremin housing, in order to add a switch which will permit you to interrupt this one grounding in case you have problems when connecting to the amp.

(Sorry for this bad English, I'd prefer explaining all that in French or German...)
Posted: 1/17/2008 7:20:49 PM
jluciani

From: Massachusetts

Joined: 8/18/2007

It is possible that the ground loop could
produce noise or hum. Since the connection from
signal ground to earth ground is a single wire
it easy enough to change.

(* jcl *)

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