Forums

The x-Chapters: A missing topic!

Started by olaf January 26, 2020
I am just reading the first page of the "The x-Chapters"

When I read the line: "PWM for dc motors - a myth demolished" a
thought pop out of my brain:

There is something missing:

The peltier element - how to avoid PWM and ripple.
Fun with PIR sensors - what you should do and what not.

The LM741 - please dont use it anymore. :-)

Any other ideas for topics we realy need?


Olaf
On Sunday, January 26, 2020 at 6:15:06 PM UTC+11, olaf wrote:
> I am just reading the first page of the "The x-Chapters" > > When I read the line: "PWM for dc motors - a myth demolished" a > thought pop out of my brain: > > There is something missing: > > The peltier element - how to avoid PWM and ripple.
PWM doesn't always work too well with Peltier elements - the heat transferred across the junction is a more or less linear function of the current through it, but the ohmic heating in the junction is proportional to the square of the current - you can use PWM to get the current you want, but you have to filter out most of the high frequency content before it goes through the junction. It's not all that difficult. Sloman A.W., Buggs P., Molloy J., and Stewart D. &ldquo;A microcontroller-based driver to stabilise the temperature of an optical stage to 1mK in the range 4C to 38C, using a Peltier heat pump and a thermistor sensor&rdquo; Measurement Science and Technology, 7 1653-64 (1996) <snip> -- Bill Sloman, Sydney
On Sunday, 26 January 2020 07:15:06 UTC, olaf  wrote:
> I am just reading the first page of the "The x-Chapters" > > When I read the line: "PWM for dc motors - a myth demolished" a > thought pop out of my brain: > > There is something missing: > > The peltier element - how to avoid PWM and ripple. > Fun with PIR sensors - what you should do and what not. > > The LM741 - please dont use it anymore. :-) > > Any other ideas for topics we realy need? > > > Olaf
good topics are almost endless. You can only put so much in a book. NT