[TriEmbed] Coffee roaster sanity check

Craig Cook cncook001 at yahoo.com
Thu Jan 9 20:08:26 CST 2020


I appreciate everyone's advice. I think I added to the confusion of what I am playing with.

Here is a summary of what I think I need.

Two main parts. 
1. Heater coil run from 120 VAC.
2. Fan that by default is run from 20 VAC but seems to be a DC motor, a bridge rectifier is being used for the conversion.

The heater coil control is using 113 VAC and has 11.2 ohms. I believe that means there are 10 amps involved.

I plan to use one of these:

Solid State Relay Module 3-32V DC Input 24-380VAC SSR-25DA 25A 

It has screw terminal connections.

It will be connected to a digital line on the Arduino to control it using PWM.

I believe we have agreement this is a good approach for the heater coil.


For the Fan I was basing my ideas off this: 
https://itp.nyu.edu/physcomp/labs/motors-and-transistors/using-a-transistor-to-control-high-current-loads-with-an-arduino/

It seems to control a 12 VDC motor using a FQP30N06L 60V LOGIC N-Channel MOSFET


The fan I am using seems to be running from 20 VAC with a bridge rectifier.

Plan A

Use an external 19 VDC, 2A power supply with a FQP30N06L to do PWM to control fan speed. Based on my understanding of the nyu tutorial, I think that should work. The onboard 20 VAC supply will not be used.

Plan B

Use the built in 20 VAC supply with something else to do PWM control for fan speed.

I believe the consensus for Plan B is to use an AC Solid-State relay.

Given that I know 20 VAC and 58.3 ohms are involved with the inner coil, I believe that means there is 0.34305 amps involved.

If I want to use the existing AC line, I could use one of these to control it https://www.digikey.com/product-detail/en/ixys-integrated-circuits-division/CPC1706Y/CPC1706Y-ND/3077519 (along with resistors to drop the ardunio digital control into the 1.2 VDC range)


For both Plan A and B I was planning to leave the bridge rectifier in place.

The latest kicad, pdf and photos live here: https://drive.google.com/drive/folders/141Y2Q9tdyt8iiL_LouNO4CarcEIShBtb

Is my understanding correct?

If both Plan A and B will work, is there a reason to pick one to start with?

Should I scrap the idea of using FQP30N06L and use the CPC1706Y instead?

Thanks

Craig




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