I use a 10K Ohm 50W Ohmite rotary rheostat connected between the wall plug (230 VAC) and a desk fan to cool a shelf in my rack that contains an SET tube amplifier. It's not fancy, or pretty, but it's quiet and effective.
However, a lead broke and I can't figure out how to rewire it. I don't want to cause a short. I have attached a drawing in a word file that shows the 2 wires in from the plug, where I cut the wires, and the 2 wires leading to the fan. The rheostat - also shown - sits in between where I made the cut. I know I need to only wire one of the side tabs on the rheostat (that determine the direction of the control) and the center tab, but am not sure which wire(s) goes to which, or if either one of the pairs simply bypasses the rheostat.
Can someone please show how to connect the 2 brown and 2 blue wires so the rheostat controls the fan speed? It worked before.
I hope the attachment works. I Can't get it to work. CRAP. I'll try later. Must run to birthday party! Maybe someone can just PM me and I can send the attachment via email.
Thanks very much.
However, a lead broke and I can't figure out how to rewire it. I don't want to cause a short. I have attached a drawing in a word file that shows the 2 wires in from the plug, where I cut the wires, and the 2 wires leading to the fan. The rheostat - also shown - sits in between where I made the cut. I know I need to only wire one of the side tabs on the rheostat (that determine the direction of the control) and the center tab, but am not sure which wire(s) goes to which, or if either one of the pairs simply bypasses the rheostat.
Can someone please show how to connect the 2 brown and 2 blue wires so the rheostat controls the fan speed? It worked before.
I hope the attachment works. I Can't get it to work. CRAP. I'll try later. Must run to birthday party! Maybe someone can just PM me and I can send the attachment via email.
Thanks very much.
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Best to attach a jpg or png file. Not everyone wants or can open a doc. Here is how to add files including non standard such as doc.
To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it forward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that.
To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it forward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that.
If you have an Ohm meter you can figure this out. Unplug from the wall first.
The correct pair of output wires show a short at full counterclockwise, increasing to maximum resistance as you turn clockwise.
Do not attempt to measure voltage when plugged in, this is dangerous.
Otherwise you can identify this visually.
The center tab will be the variable connection, and when looking at the knob side, the "common" tab will be just clockwise of the center tab.
That is, with all three tabs at the bottom, the common tab is the left one. Use this one and the center tab.
OK. Brown in to left tab, brown out from center tab. Blue in to blue out (no connection to rheostat). Thanks much.
Like this? The blue wire is hard to see, but is wired from the source to the fan without any contact at the rheostat. I guess I could also switch the wires and maybe wire up the right tab (only) instead?
Attachments
That is wired in series with the supply. If you used the other tab (and the middle, you always use the middle as one of them) then the control would work "back to front".
Yes, I only helped him with this because he already was using the rheostat.
I've also used small autotransformers for lighting. They work great.
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