Hi all, I'm trying to automate my coffee grinder.
I need to control two motors: the large AC grinder motor, and a much smaller 5V DC motor to operate the ground coffe chute.
No problem on software part, some problems on the hardware... I think I already blew a uC hooking it up to a inadeguate circuit, so, is this one ok? Any suggestions?
(not depicted: small lcd display on I2C pins)
I didn't identify any problem in your schematic that could damage the Arduino.
I think this 10K resistor in the red circle is either drawn in the wrong place or is unnecessary. (connected between +5V and Gnd).
Thanks.
Yes I drew it wrong, actually it's a standard switch with pulldown resistor configuration.
second thing, AC/DC adapter output is 5V, but you attach it to wrong pin
You won’t be able to drive the relays with that transistor circuit - the relay needs to be between the collector and 5v .
Why the diode in the power supply output. ? -you can’t really afford to loose 0.6 volts.
The 10k base resistors are a bit high , 1k would be better ; but you should calculate !
If the power supply is 5v ; connect to the 5v pin , not vin.
It's on VCC pin, isn't that right?
In the first iteration (the one that possibly blew the uC, ehm) the chute motor drew too much current on startup and Arduino shut down briefly, crashing the program, so I added the cap.
I got the suggestion to insert a diode too, to avoid the motor draining the capacitor should it briefly stall.
I know I am losing some .7 V, I might compensate cranking up the output voltage from the regulator.
Use schotky diode to reduce voltage drop.
Also: use pnp transistors (and inverse logic) or move relays as @hammy suggested.
The relays may very well lead to a voltage drop. 470 uF is not that much of a buffer. But all depends on current drawn by relays plus current drawn by motor compared to current output of 5V source...
10k should stay, but switch should be moved to 5V to pin/resistor lead...
Your schematic shows the power supply connected to Vin, not VCC (the +5V pin).
Arduino Nano Every has VCC pin? Did you mean 5V?
I find it risky to connect the external power supply to the 5V pin.
I was referring to the 5V pin as Vcc, there is no labeling on the board as such.
Vin is the input to the voltage regulator, so generally not where you would want to connect a regulated 5V power supply (which in this case is closer to 4.3V because of the diode).
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