2 x temperature probes that can read up to 100deg C (and their interfaces if needed)
1 x buck converter up to 12Vdc at 2 Amps.
I will use the temp probes to measure the temperature in a box and I want to heat the box slightly above room temperature with a car tail lamp. I am doing it now with a variable voltage power supply (Lab Supply) and @ 5 V and 1.7Amps is pretty good but I need better temperature control.
Can I buy an off the shelf 0 - xx Vdc (roughly 0.x to 12 ) voltage controller that can run maybe 2Amps that can be controlled by the Arduino?
And have you seen cheap temp probes that can interface with the Arduino?
100 C is boiling water temperature.
if you are heating to room temperature, why the extra range ?
an RTD is nearly linear over a much smaller range
there are a lot of chips LM34 that offer high accuracy
but, you did not state how accurate you need to be at any point.
some fruit in cold storage starts to rot at a temperature change of about 1/3 degree F
a VERY hard value to read and harder to hold.
the majority of fruit rots when the temperature swings 2 deg F.
when you get strawberries, they may have been picked last year and held in cold for the last 11 months.
a simple wall wart and an FET would do the trick for power.
you can pulse the FET on and off to generate heat you need
I was concerned many of the other 'pot' controlled supplies would require a fair bit of modification to work on 0 - 5Vdc set points as the pot is typically in the feedback loop.
Dave_vo:
I have some thermocouples coming from Ebay. I chose 100 deg C as many are rated for that.
Link?
Dave_vo:
As for the power supply I want the arduino to control the voltage.
I'm afraid you don't know how heater control works.
Arduino doesn't control the VOLTAGE to the heater, it controls the POWER.
By switching the heater on/off. Very fast if you use PWM.
If you use a car lamp as heater, just run it straight of 12volt. No buck converter.
Let the Arduino switch the heater/light on/off very fast with a mosfet.
An analogWrite of ~100 will turn the power on ~40% of the time.
40% on, 60% off, ~500 times per second.
The lightbulb will glow as if it was connected to a 5volt source.
Leo..
Before I make a circuit to do that I was hoping there might be an existing solution like a buck converter or remotely controlled power supply, off the shelf.
Wawa:
Let the Arduino switch the heater/light on/off very fast with a mosfet.
An analogWrite of ~100 will turn the power on ~40% of the time.
40% on, 60% off, ~500 times per second.
The lightbulb will glow as if it was connected to a 5volt source.
Leo..
I was thinking about this...
if the existing lamp is close to the needed power, then if he duty cycles it once per minute for 6 seconds, off, he will get about 90% of the total heat.
or every 15 seconds for 1.5 seconds off.
much experimenting to do
It will be a lot harder to interface a buck supply with the Arduino.
You don't need a big circuit.
Just use a logic mosfet, a 220ohm resistor between an Arduino PWM pin and gate (to protect the pin), and a 10k resistor from Arduino pin to ground (to protect the mosfet during bootup).
Supply positive goes to lightbulb, supply negative to fet source, other pin from lightbulb to fet drain.
Source (supply negative) also connects to Arduino ground.
Test with e.g. the "fade" example in the IDE.
Leo..