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I am creating a printed circuit board that is utilizing a circuit from a sparkfun product: (https://www.digikey.ca/product-detail/en/sparkfun-electronics/SEN-12642/1568-1290-ND/5762440)

I have sourced all of the components on the schematic provided by sparkfun with the exception of a schottky diode. They specify part number RB751. Which I have found on digikey: https://www.rohm.com/datasheet/RB751VM-40/rb751vm-40te-17-e

However it is incredibly small, and I don't have the skills or the equipment to solder somthing this small. I would like to find a through hole substitute, or at least a larger a package for this diode. So my question is (hopefully this isn't too broad or open ended): What are the key values that are important for a diode in a circuit like this? Can anyone suggest a good substitute with a larger package? Thanks in advance!

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In general, you would just need to use a different Schottky diode with similar characteristics:

  • Reverse voltage
  • Average current
  • Maximum current
  • Recovery time

If a Schottky is being used it is generally to provide a low-drop (~0.2V) and thus lower wasted power, when it is conducting, as opposed to a silicon diode (~0.6V), and to gain a faster conduction/recovery time.

But just a quick look at the schematic shows me that the diode is non-critical, and nearly any signal diode (Schottky or silicon) that can tolerate your supply voltage would work in that circuit with an insignificant loss of headroom if silicon is used. A general rectifier diode might not work, as these are slower to react and could introduce undesired resonances in the amplifier.

I am only concerned about the diode across the amplifier, which is not in the common place you would use for a half-wave precision rectifier (it is connected at the cathode of the output diode instead of at the anode) and might be providing a small amount of undesired full-wave rectification. I attribute this to a design oversight.

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  • \$\begingroup\$ Thanks for the explanation Edgar, much appreciated! \$\endgroup\$
    – MattG
    Nov 27, 2018 at 19:52

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