RC filter for PTC/Peltier control

Using Arduino Project Guidance
1

Hi everyone,
I would appreciate your help regarding this circuit. I'm trying to PID control a Peltier (or PTC) connected to a 12V DC power supply and passing the PWM signal to the gate of an nMOSFET using an RC filter (10kOhm, 1uF). The (-) of the power supply is connected to its ground and that is connected to the ground of the Arduino. However, I'm in doubt regarding the ground. Should I connect everything to the same ground? Or else, the source to the Power supply ground and the gate (capacitor) to the Arduino ground. I have a thermocouple sensor (MAX something) that starts to take a lot of noise in when the setpoint is approached. The code is OK, I already used in the past, but I don't remember how I did the circuit.
Sorry, I'm trying to upload a scheme but there's an undefined error.

Thanks

scheme
scheme993×664 17 KB

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Please go back, figure that out, and post a complete schematic diagram. Hand drawn is preferred, with pins and connections clearly labeled.

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Your topic has been moved. Please do not post in "Uncategorized"; see the sticky topics in Uncategorized - Arduino Forum.

I'm not a hardware man but a RC filter on the gate of a MOSFET dfoes not sound healthy to me; you want to open and close them as fast as possible as far as I know.

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Sorry there was a problem uploading with Firefox. I uploaded it now. Thanks

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Thanks. What would you suggest? I'm not a circuit expert

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The grounding is basically OK, but the design is wrong, as it uses the MOSFET as a linear control element. This will likely destroy the MOSFET by overheating.

Something like this is workable, with straight PWM control. BE SURE to use a logic level MOSFET:

dc_motor_driver

1 Like
7

Thanks for the quick reply. I'm using an irlz14

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What is the Wattage of your Peltier or the voltage and max current.

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I'm testing the circuit with a 24V PTC (testing it at low voltage, 10V, 3A), that will eventually substituted by a UEPT-340-228-060C200S peltier module (18 V, 6A) 22 W combined with an H-bridge made with relays and two MOSFETs

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Be sure to buy plenty of Peltier devices.

As you have read, the device is a series of metallic diodes which all generate heat when the device is powered. That heat is normally dissipated by the Peltier effect moving that heat to the output plate for dissipation. If you turn the device off before the heat is moved, and then back on again, you just add to the internal heat and it remains in each diode until one opens up. But have fun!

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That MOSFET will be OK at 3A with a heatsink and using PWM without the RC filter.
At 6A you need to find one with a lower Rds(on)