EZDUAL BOM Questions

[TedS]

Hi Evan,

I've started working on my EZDUAL to go with my EZDAC. I've found a
couple of things I'm unsure of on the BOM:

First, the first line item is R1A, R1B, etc., with 6 items listed.
However, the Mult Factor in the BOM only shows 4. Do I need 6 or 4 of
these?

Second, on the schematic and on the PCB drawing there are D3, D4, D5,
and D6, but these don't show up on the BOM. What are these, are they
necessary, and what part numbers should I order if I need them?

Thanks,
Ted

[ezkcdude]

Ted, thanks for pointing out the mistakes in the BOM. It should be 6,
but you can use 2 on each side, or even just one. Remember that the
resistors are in parallel, so we want a total resistance around
10-15R. If you remember circuits, you know that you must add the
resistors as follows:
1/R1+1/R2+1/R3=1/Rtotal

So, for Rtotal=10R, we would want R1,2,3=30R. If we only use two
resistors, then R1,2=20R, and for one resistor, R1=30R. Does that make
sense?

As for the diodes, those are now in there. That was an oversight. As
you will see, you can use the same diodes as for the rectification
side. Actually, you could use even lower rated ones, but you would
probably save a few pennies by buying more of one type (N4002). Let me
know if you have any more questions. Good luck. I look forward to
seeing the results.

[TedS]

Thanks for the clarification, Evan.

I do remember some basic circuits, but I have to rely on you for this
one (and the DAC)! Actually I've already got 4 of the 6 30-ohm
resistors; so two paralleled together on each side gives me 15 ohms
(the resistance of two equal resistors in parallel is 1/2 the value).
Are you saying that just having the 15 ohms there is OK for your
circuit?

[Evan Zamir]

It would be fine with what you have, especially if you're wanting to finish it ASAP. Also, you could always just add the other resistors when you get them later. No problem. I've made the ezdual using 2 resistors on each side, and it was fine.
-evan

[TedS]

Cool! Thanks!
Ted

On May 15, 6:07 pm, "Evan Zamir" <zamir.e...@gmail.com> wrote:
> It would be fine with what you have, especially if you're wanting to finish
> it ASAP. Also, you could always just add the other resistors when you get
> them later. No problem. I've made the ezdual using 2 resistors on each side,
> and it was fine.
> -evan
>

> > > seeing the results.- Hide quoted text -
>
> - Show quoted text -