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Diodes are diodes?  That is inconceivable!

No, they are diodes.

is there some way to make this uncompatible with Ultrasones?

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Did you have any luck locating a 47uf ceramic? I've been hunting and can't find one greater than 10V. :(

Old thread, sorry: Kevin, do you have a schematic for the current version of this board?

//UFN

EDIT: Oh, and some BoM-questions:

1) I assume the diodes are just standard 1N4148/1N914?

2) Is the 47uF cap supposed to be ceramic or similar since it hasn't got the same footprint as the electrolytics?

Edited by GrindingThud
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Well, it seems the 25V part is backordered at Mouser until February. I haven't done anything yet, but maybe a 47uF bipolar electrolytic will work instead? Looks like you can get at least an 8mm part into the board (and maybe 10mm at a pinch).

 

//UFN

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Yea, that's what I'll probably do for test until they come in. :)

Well, it seems the 25V part is backordered at Mouser until February. I haven't done anything yet, but maybe a 47uF bipolar electrolytic will work instead? Looks like you can get at least an 8mm part into the board (and maybe 10mm at a pinch).

 

//UFN

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  • 2 weeks later...

1. For the 100uF cap, I measured the leads at 2.5mm, and thought to use 647-UMA1E101MDD from Mouser. Is that adequate?

 

2. There are 7 short components on the board labeled "100k" left of the terminal blocks, but they don't look like normal resistor silkscreen images (2 by the in block, 3 by the out block, 1 to the right of each row of 1uF caps). Are they just resistors I'm supposed to mount at an angle so they fit?

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  • 2 weeks later...

I was going thru the schematic and the gerbers for this to do a layout including a muting switch and Molex KK connectors, which I like better than the terminal blocks. From what I am seeing in the gerbers, I had a couple of questions:

 

  • It appears that the LM339s are powered by V+/V- rather than V+/GND?
  • The LM339 has 4 comparators in it. It appears that 2 are being paralleled for each input signal?
  • The input protection diodes run from V+/V-?

Protect_input.JPG

  • There are a couple of 1uf capacitors (the yellow ones on GrindingThud's board above) that I am not sure where these go?

I attached a pdf of the Eagle schematic I have worked up so far.

 

 

Gilmore_protect3_schematic.png.pdf

Edited by Pars
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  • It appears that the LM339s are powered by V+/V- rather than V+/GND?

yes

  • The LM339 has 4 comparators in it. It appears that 2 are being paralleled for each input signal?

yes, one for the + limit, the other for the - limit and then repeated 4 times for each of the signals

  • The input protection diodes run from V+/V-?

to the inputs of the lm339, not as shown.

 

this should make it easier

 

http://gilmore.chem.northwestern.edu/protector3.jpg

Edited by kevin gilmore
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This version should incorporate all of Kevin's corrections from my previous version.

 

One further question:

 

I know on Ti Kan's protection circuit, the relay drive requirements were pulling the + rail down, though he was using a virtual ground scheme on his. A user was the one who suggested the use of the 2N7000 and a 24V rather than a 12V relay, so that both rails were involved in supplying the relay drive.

 

I notice here the you are using a 12V relay and driving it with V+ / GND. In actual use, does this present any problems?

 

 

Gilmore_protect3_schematic.png.pdf

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