Astatic D-104 Preamp

[Axldeziak]

Here's a layout for a Astatic D-104 preamp. They were installed in desktop ham radio mics but appear to be a pretty general buffered preamp. I'm sure it could be used for alot of things.



The unit I traced this from is dated 9-75 and has 2SC828 transistors. Researching them I found earlier units had 2N2712 installed.

Some substitutions I found listed were:
BC168, BC183, BC238, BC548, BC182L, 2N3710, 2SC536, 2SC945, KT315B, BFP20
and
2N3904, (swap C+B)

A mod I found was to add more bass:
Add a 33K resistor in series with the input.
Change the 10nF capacitor to 220nF.
Change the 100nF capacitor to 4.7-6.8pF
Change the 4.7uF capacitor to 1.5pF

Here's a schematic I drew up from my mic's trace.

[Teddeeh]

Any chance of a stripboard layout??

[Axldeziak]

I added a stripboard layout to the first post. (I also corrected a small error in the vero and redrew the schematic a bit.)