PoWEr
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Magnetic stirrer with heating, own temperature sensor
So long story short my old magnetic stirrer broke and I've got a new one, SH-2. My issue is that it doesn't have a built-in temperature display so I
have no idea what temperature Im setting to. While I could refund the one I have and buy one that has it, in parameters they can't go higher than
100C. So what I came up with is either to just experiment with a beaker of water and thermometr and mark certain points on the valve (Im 100% sure it
will have some point of error and probably not work well for other liquids) or buy a temperature sensor (I found PT100, which are apparently very good
and they're cheap) and an external temperature display (the ones I found for some reason cost as much as the magnetic stirrer). Any other ideas that
could be better?
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bnull
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You can build a circuit to convert the reading of the sensor to a value directly proportional (meaning 1 mV = 1 °C, or something similar with ohms
and degrees Celsius). The only other thing you'd need would be a voltmeter, which is a good thing to have by its own merits anyway.
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MrDoctor
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get a PID controller instead and just use that. it has the added benefit of, if you install a port for a second sensor and a bypass switch, you can
use two thermocouples, and essentially choose sometimes to regulate by solution temperature, or oil bath temp, etc, rather than plate temp which is
useful when lots of heat is lost by gas/reflux so plate temp has to be considerably more than solution temp. a type K thermocouple will happily read
up to 500C or more, just be mindful that wire insulation burns, and the thermocouple should probably be protected from oxygen at very least.
if you arent familiar with PIDs, they arent simple limit switches, they adjust duty cycle (you can/may need to tune this tho, note heating mostly just
uses P and a little I, no D is needed) such as that they would heat up quickly then back off as they reach their target, and works to maintain it
rather than oscillate around it.
Also you might not be able to switch based on, and read, the temp from the same thermistor otherwise, youd need two.
Have a look at TM902C, they are great to have, and dirt cheap too.
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PoWEr
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Quote: Originally posted by bnull  | | You can build a circuit to convert the reading of the sensor to a value directly proportional (meaning 1 mV = 1 °C, or something similar with ohms
and degrees Celsius). The only other thing you'd need would be a voltmeter, which is a good thing to have by its own merits anyway.
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Sorry, I forgot to add in the main post my problem with sensor. How do I use it in distillation setups? I won't be able to put sensor inside the flask
or else gas will leak.
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Axt
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W2022 AC110/220V Precise Temperature Control 1500W Smart Digital LED Display Thermostat Microcomputer Temperature Controller
https://www.aliexpress.com/item/1005009561285975.html?spm=a2...
This isn't really what you are looking for, (well it'd work, but it will keep switching your stirrer on and off). Rather it just fits the topic title.
I bought one to maintain a temp of a sand bath inside a vacuum drying chamber.
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MrDoctor
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| Quote: Originally posted by PoWEr | | Quote: Originally posted by bnull | | You can build a circuit to convert the reading of the sensor to a value directly proportional (meaning 1 mV = 1 °C, or something similar with ohms
and degrees Celsius). The only other thing you'd need would be a voltmeter, which is a good thing to have by its own merits anyway.
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Sorry, I forgot to add in the main post my problem with sensor. How do I use it in distillation setups? I won't be able to put sensor inside the flask
or else gas will leak. |
get some glass tubing, i forget the best size, basically whatever your thermometer ports inner diameter is. you melt one end shut. now you have a
perfectly airtight glass thermo-well that can be submerged anywhere either through a side-arm, or in the distillation head.
type-K thermocouples are literally just a blob on the end of some wire so they fit effortlessly inside. this is my go-to since it works under vacuum.
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