[sdiy] Discrete OTA

[Tom Wiltshire]

On 3 Apr 2014, at 23:18, David G Dixon <dixon at mail.ubc.ca> wrote:
>> 
>> I can see good reasons for something potted being better - 
>> more robust, better protection from the environment, more 
>> thermally stable and consistent, etc. What are the advantages 
>> of "no potting" beyond "repairability" (which should be a 
>> once in twenty years thing if it's done right).
> 
> Why would potting make something more robust?  I don't know -- potting just
> pisses me off, I guess.

I agree with Tom's point that doing the potting is a manual ball-ache. But potting definitely makes things more robust. I used to work for a company making data logger products which were regularly to be found measuring water depth in sewers and other such unsavoury locations. Potting the electronics was essential to ensure even a half-way reasonable chance of survival. Obviously synth circuits don't have the same environmental demands placed on them, but "potting has its uses" is all I'm trying to say.

As to repair, yes, potting makes it much harder, but you wouldn't believe some of the stuff we fixed after having rinsed the (ahem) crud off it and dug the potting out with a sharpened screwdriver! Now, *that* was a manual ball-ache!

I now see Neil's post has just arrived, and my points are repeats of his - so +1 what Neil said.

T.