Electronics > Projects, Designs, and Technical Stuff
Temperature Comparator
seanhaz:
Hey,
Im an Electrical Engineering student and still in my first year of study so im still pretty new to everything.
I want to build a circuit that compares the temperature of two temperature sensors and gives a variable PWM output to a motor to adjust the speed and also for it to run off solar powered with a small battery backup.
i have attached my circuit diagram i have created, Im using two LM35 temperature sensors giving signals into a ATtiny85 microcontroller in which i will write my program that will give a variable PWM signal depending of the temperature difference of the two sensors.
is there anything you suggest i should change? or anything im missing?
any advice is very welcomed.
Andreas:
--- Quote from: seanhaz on October 03, 2013, 07:43:00 am ---is there anything you suggest i should change? or anything im missing?
any advice is very welcomed.
--- End quote ---
I would place a additional 100nF directly at the ATTiny at the power pins.
The motor return line should go directly to the battery and not across the ATTiny + sensor lines.
How long are the sensor lines? Eventually you will need further decoupling capacitors for the sensors + input low pass filtering for the ADC-inputs.
With best regards
Andreas
dannyf:
1. you need a logic level mosfet;
2. gate resistors too big.
3. solar panel shorted by the battery.
...
this is soething a 555 + two ptc/ntc sensors could do
seanhaz:
--- Quote from: Andreas on October 03, 2013, 07:55:27 am ---I would place a additional 100nF directly at the ATTiny at the power pins.
The motor return line should go directly to the battery and not across the ATTiny + sensor lines.
How long are the sensor lines? Eventually you will need further decoupling capacitors for the sensors + input low pass filtering for the ADC-inputs.
With best regards
Andreas
--- End quote ---
thanks for the reply,
is the extra 100nF cap at the ATtiny to give it a more stable voltage?
and routeing the motor directly to the battery due to interference?
the sensor lines will be 2-3meters
seanhaz:
--- Quote from: dannyf on October 03, 2013, 08:22:02 am ---1. you need a logic level mosfet;
2. gate resistors too big.
3. solar panel shorted by the battery.
...
this is soething a 555 + two ptc/ntc sensors could do
--- End quote ---
thanks for your reply,
I thought the FQP30N06L was a logic level mosfet?
what size resistors do you recommend?
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