On Mon, 22 May 2006 04:55:24 -0400, Nelson
wrote:

Sears Blower DC Motor Speed Control, PCB #7004317-00

Component has two leads, upright rectangular epoxy case about 1 cm
square, 5 mm wide with ".047J400" stamped on top. I'm guessing it's a
Diac, but I can't find it listed anywhere.

D1 is likely to be a diac.
Your little rectangular box contains a 47 nF 400 Volt capacitor.

--
Kind regards,
Gerard Bok

On Mon, 22 May 2006 09:17:11 -0400, Nelson
wrote:

On Mon, 22 May 2006 06:53:56 -0400, Gerard Bok wrote
(in article ):

On Mon, 22 May 2006 04:55:24 -0400, Nelson
wrote:

Sears Blower DC Motor Speed Control, PCB #7004317-00

Component has two leads, upright rectangular epoxy case about 1 cm
square, 5 mm wide with ".047J400" stamped on top.

What is the significance of the "J" ?

Not a clue :-)
But probably some indication of temperature range or precision.
Anyway: something you can probably ignore for a motor speed
control :-)

--
Kind regards,
Gerard Bok

J typically stands for 5% tolerance

In article , Nelson
wrote:

On Mon, 22 May 2006 06:53:56 -0400, Gerard Bok wrote
(in article ):

On Mon, 22 May 2006 04:55:24 -0400, Nelson
wrote:

Sears Blower DC Motor Speed Control, PCB #7004317-00

Component has two leads, upright rectangular epoxy case about 1 cm
square, 5 mm wide with ".047J400" stamped on top. I'm guessing it's a
Diac, but I can't find it listed anywhere.

D1 is likely to be a diac.
Your little rectangular box contains a 47 nF 400 Volt capacitor.



Makes sense. Thanks. Now that I look a D1 closely, I can see that
what I mistook for the anode band is actually the junction between the
two parts in the middle. Tiny little bugger :-)

What is the significance of the "J" ?

Nelson & Gerard-

The "J" is most likely the tolerance of the capacitor, I'm guessing 5 percent.

Your diagram came across a little distorted, but it appears that what you
call a diode is more likely the capacitor as Gerard suggested.

What you call a diac (D1) may be the full-wave equivalent used to trigger
a triac on both halves of the cycle. I don't recall what it is called,
possibly a three-layer diode or something like that. I have a home-made
version built about 30 years ago.

Fred

"Fred McKenzie" wrote in message
...
In article , Nelson
wrote:

On Mon, 22 May 2006 06:53:56 -0400, Gerard Bok wrote
(in article ):

On Mon, 22 May 2006 04:55:24 -0400, Nelson
wrote:

Sears Blower DC Motor Speed Control, PCB #7004317-00

Component has two leads, upright rectangular epoxy case about 1 cm
square, 5 mm wide with ".047J400" stamped on top. I'm guessing it's a
Diac, but I can't find it listed anywhere.

D1 is likely to be a diac.
Your little rectangular box contains a 47 nF 400 Volt capacitor.



Makes sense. Thanks. Now that I look a D1 closely, I can see that
what I mistook for the anode band is actually the junction between the
two parts in the middle. Tiny little bugger :-)

What is the significance of the "J" ?

Nelson & Gerard-

The "J" is most likely the tolerance of the capacitor, I'm guessing 5
percent.

Your diagram came across a little distorted, but it appears that what you
call a diode is more likely the capacitor as Gerard suggested.

What you call a diac (D1) may be the full-wave equivalent used to trigger
a triac on both halves of the cycle. I don't recall what it is called,
possibly a three-layer diode or something like that. I have a home-made
version built about 30 years ago.

Fred

I think there may be a diac type designated DB2 - try a search and see.