Stir plate build question

[fretman124]

I'm building a stir plate from the plans off a previous thread. https://www.homebrewtalk.com/showthread.php?t=8850 in the schematic for the circuit, the capacitors are shown to be installed with respect to polarity.

I have two ceramic capacitors to install and I can't seem to tell what the polarity is. They are Radio Shack. Nothing on the package nor on the item itself indicates which lead is anode and which is cathode. Any suggestions?

This is what is on the capacitor its self

104M
------- -

It is actually a solid line under the number with a microscopic space and dash. Is that little dash the idicator and if so, what? positive or negative?

 

[JoeRags]

Ceramics usually arent polarized.

 

[fretman124]

OK....thanks.

Now if I can keep the 2 year old from playing with the soldering iron.........

 

[JoeRags]

Just curious... you say you have two ceramic caps... they should be 0.1uf and 1uf... typically, the 1uf will be electrolytic. Just want to make sure you've got the right parts.

Good luck

 

[Scimmia]

Just curious... you say you have two ceramic caps... they should be 0.1uf and 1uf... typically, the 1uf will be electrolytic. Just want to make sure you've got the right parts.

Good luck

Actually, from the datasheet, the output cap should be 1uf if it's solid tant, or 25uf if you use electrolytic. Of course, this cap is optional, anyway, and the ceramic will act more like a tant than an electrolytic. I usually use whatever I have around, I think it was a salvaged 100uf electrolytic when I built my stirplate.

 

[fretman124]

interesting now that I have burnt the crap out of my fingers and put it all together.

I went off the parts list the OP posted. Nothing was said about a 1 uf cap. parts list said a 2-pack of 0.1 uf ceramic capacitors. I saw the 1 uf in the schematic but thought it was a typo or the line covered the dot.

This is the parts list I used
lm317 circuit parts
TO-220/TO-202 Aluminum Heat Sink 276-1368
10K-Ohm Linear-Taper Potentiometer 271-1715
Adjustable-Voltage Regulator LM317T 276-1778
1K Ohm 1/4-Watt Carbon Film Resistor5 Pack 271-1321
0.1µF 50V Hi-Q Ceramic Disc Capacitor Pk/2 272-135
Dual Mini Board with 213 Holes 276-148

and now that I re-read the post, I see the 1 uf cap.

Off to the parts store

 

[Scimmia]

Honestly, I probably wouldn't bother. As I said, that cap is optional anyway, and in this application, it's pretty trivial. The .1uf should be fine.

 

[fretman124]

Honestly, I probably wouldn't bother. As I said, that cap is optional anyway, and in this application, it's pretty trivial. The .1uf should be fine.

now ya tell me....

went and bought the right one.

All done with the hot metal part. Now to put it together.

Nobody around here (computer repair shops) want to give up hard drives for the magnets. Something about customer data on them, theft of info and crap like that.

I have some very strong magnets a bit bigger than a pencil in diameter and about 1.5 inches long. Think one or two of those will work?

 

[Scimmia]

now ya tell me....

went and bought the right one.

All done with the hot metal part. Now to put it together.

Nobody around here (computer repair shops) want to give up hard drives for the magnets. Something about customer data on them, theft of info and crap like that.

I have some very strong magnets a bit bigger than a pencil in diameter and about 1.5 inches long. Think one or two of those will work?

They may work, but mounting them could be an issue. Are they silver? They usually put a silverish plating on neodymium magnets. Give it a shot, and if it doesn't work, hit Hobby Lobby or something, 6 magnets for $3.