Rate my mods? Fluid bed Phidgets rebuild - Page 2

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
randytsuch
Posts: 502
Joined: 15 years ago

#11: Post by randytsuch »

Thread on the out1100 and artisan and heater control

Artisan and Phidgets control of AC heater using SSR

Mr_Flauschig (original poster)
Posts: 18
Joined: 2 years ago

#12: Post by Mr_Flauschig (original poster) »

Just a brief update - I got my scope working, but discovered that my roaster uses a floating ground. If you try to connect it to earth ground, you blow the fuse. So I can't modify the roaster as it is, as the Phidgets/laptop connect to earth ground. If I do want to use the roaster hardware, I will have to build up a complete power supply, which I've done in the past, but don't really want to do, its really time consuming. Or I have to find a way to isolate the two ground planes from each other, which might be easier.

randytsuch
Posts: 502
Joined: 15 years ago

#13: Post by randytsuch »

Wondering where the laptop/phidgets part is earth grounded?

I expect the laptop to be floating, so does the phidgets stuff tie to earth?

And per your diagram, there are opto's between on the phidgets output end, so were do the grounds tie together?

Seems like you should be able to disconnect them.

Randy

Mr_Flauschig (original poster)
Posts: 18
Joined: 2 years ago

#14: Post by Mr_Flauschig (original poster) »

Ah, all good questions.

The laptop power supply brick is three prong to the wall, and the DC power from the brick to the laptop appears to not reference the earth ground of the brick. That being said, one still shouldn't expose the world to a floating ground, at least in general.

About the optoisolator, you are very correct, looking back at the schematic, I should be able to connect the Phidget output to the optoisolator input without having to reference any ground. I didn't think it through completely, as I've been probing the roaster elsewhere. Very good point. Now to get a new fuse :D