November 2011 Archives

Umbilical'd Amplifier

| No Comments | No TrackBacks


Itsa damp design...

This circuit is based on the TDA7350A by ST, which is a robust car radio amplifier.  It supports 22 watts of bridged output, which is then sent through a 50'+ underwater umbilical, into a dive mask.  The line matching transformer is actually milspec; it was the only one which fit the bill!  The current version is hand wire-wrapped and placed within a NEMA box.  But though sealed and packed with desiccant, everything electronic is mortal in a saltwater environment.  With PCB's in stock, we'll be able to quickly produce new units.  This first revision is a bit spacious, the next one will likely have two units in the same panel space.  The panel pins will also be better utilized i.e. for the pot header.

This is what happened to the original board:

Enhanced by Zemanta

CdS Transistor Candles

| No Comments | No TrackBacks

yes, not the nicest looking circuit...

Recently Jon Britton and I participated in the Educator Extravaganza, in which we delved into the electronics at our jobs, and gave educators a peak under the hood.  One gizmo we left people with was the CdS Transistor candle, pictured above with the lamp gone all bokeh.

It's essentially one of the simplest and most educational circuits that can be made, without handtools, solder or even a breadboard.  For me, its entirely magical, and goes the distance at instilling an intuitive understanding of electronics.  According to one high school physics teacher, it even fit a state standard to explain "how transistors work."

I've attached the lesson plan with bill-o-materials and procedure (scrambled together, errors and all, half an hour prior to the event) here:  eextrava.pdf

Enhanced by Zemanta

About this Archive

This page is an archive of entries from November 2011 listed from newest to oldest.

October 2011 is the previous archive.

December 2011 is the next archive.

Find recent content on the main index or look in the archives to find all content.