[TriEmbed] Coffee roaster

[Brian]

On 10/29/18 11:23 PM, Craig Cook via TriEmbed wrote:
> <background info snipped>
> 
> Actually, given I am only dealing with 110V, is there a better solid state relay choice?

One that isn't obsoleted is a good choice! :-)  But yes, I think I made 
a comment earlier that you should be able to find a suitable 120-V SSR 
with similar current rating (AC side) and trigger characteristics (DC 
side).  DigiKey's parametric search is very useful for this.

> I have some of these "IRF510N IRF510 Power MOSFET N-Channel 5.6A 100V" 

Useful things to have around!

> Can I use one for the heater coil 

No.  MOSFETs are DC devices.  A MOSFET conducts in reverse-bias (when 
the source pin is at a higher potential than the drain pin).  Using a 
MOSFET on an AC signal would only turn the load OFF for half the AC 
cycle (the load would always be ON during the reverse cycle).  Not to 
mention, of course, that the 100 V drain-source rating is too low.

> and another for the fan motor?

You can definitely use one of these MOSFETs for the fan motor.  You 
might also want to connect a flywheel diode across the motor to protect 
the MOSFET from back-emf spikes when it switches off (this is a diode 
connected in reverse-bias across the motor's terminals that provides a 
safe path for the spike of reverse current that is caused by the motor's 
magnetic field collapsing).

> I also have some of these "039N04L MOSFET"

That is a 40-V, 80-A MOSFET.  It too would be suitable for the motor 
control.

I really encourage you to get familiar with DigiKey's website.  They are 
a supplier of electronic components and present an absolute wealth of 
data on various devices.  You can almost always enter a specific part 
number into the search field and find out the specs on the component and 
get access to a data sheet with just one or two clicks.

I'd also encourage you to check out some of the books by Forrest M. Mims 
III.  He's written some really great, easy-to-understand books and 
booklets on introductory electronic concepts, mastery of which will 
equip you to answer these design questions with confidence on your own 
(not to say we are/I am not happy to help!).

Cheers,
-Brian