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Electronics => Beginners => Topic started by: user1235423643 on August 12, 2016, 04:32:01 pm

Title: fan thermo switch east simple - temp control
Post by: user1235423643 on August 12, 2016, 04:32:01 pm
hello, can anyone help find some info on how to make a temp control switch

i want to turn on a cooling fan when temp is at X or over. simple and cheap to build.

some extra factors if possible
* speed control (high the temp faster the speed)
* temp range adjustment (pot)

thanks
Title: Re: fan thermo switch east simple - temp control
Post by: Seekonk on August 12, 2016, 05:20:50 pm
I buy these digital 12V ones on ebay for a little over 4# shipped nice features like relay out, display, delay, diff, heating or cooling and even correct the temp.  Blame Jimmy Carter if you can't read C.
Title: Re: fan thermo switch east simple - temp control
Post by: Ice-Tea on August 12, 2016, 05:32:03 pm
Airpax for on/off. Up to 48V or thereabout.
Title: Re: fan thermo switch east simple - temp control
Post by: user1235423643 on August 13, 2016, 07:33:18 am
umm like to shared a link or something?
Title: Re: fan thermo switch east simple - temp control
Post by: Ice-Tea on August 13, 2016, 07:41:42 am
No problem!

http://lmgtfy.com/?q=Airpax (http://lmgtfy.com/?q=Airpax)
Title: Re: fan thermo switch east simple - temp control
Post by: user1235423643 on August 13, 2016, 02:19:14 pm
your link doesn't work. if you dont have a valid reply dont bother please.
Title: Re: fan thermo switch east simple - temp control
Post by: Ice-Tea on August 13, 2016, 04:37:51 pm
Holy crap, dude. Google it. First hit.
Title: Re: fan thermo switch east simple - temp control
Post by: ZeTeX on August 13, 2016, 08:25:45 pm
https://www.eevblog.com/forum/projects/'active'-dc-fan-controller/msg896072/#msg896072 (https://www.eevblog.com/forum/projects/'active'-dc-fan-controller/msg896072/#msg896072)
Title: Re: fan thermo switch east simple - temp control
Post by: user1235423643 on August 14, 2016, 09:22:58 am
thanks ZeTeX,   

@ice-tea dont bother with your useless comments.
Title: Re: fan thermo switch east simple - temp control
Post by: user1235423643 on August 14, 2016, 09:25:41 am
looking for something more simple

like a transistor and a variable output controlled by the base resistor
Title: Re: fan thermo switch east simple - temp control
Post by: Refrigerator on August 14, 2016, 10:14:13 am
I made a thread about a circuit that i came up with, which uses a diode as a temp sensor, even the P-N junction on a transistor can be used.
Here's the schematic:
https://gyazo.com/a938d6d9342c326f5a9762de5edf3482 (https://gyazo.com/a938d6d9342c326f5a9762de5edf3482)
The full thread:
https://www.eevblog.com/forum/projects/i-came-up-with-this-temp-controlled-fan-circuit/msg691717/#msg691717 (https://www.eevblog.com/forum/projects/i-came-up-with-this-temp-controlled-fan-circuit/msg691717/#msg691717)
I hope it's what you're looking for.
Title: Re: fan thermo switch east simple - temp control
Post by: user1235423643 on August 24, 2016, 05:03:06 pm
more simple.

one transistor and a theoristor on the base to vary the voltage?

 
Title: Re: fan thermo switch east simple - temp control
Post by: ZeTeX on August 24, 2016, 06:43:57 pm
more simple.

one transistor and a theoristor on the base to vary the voltage?
You mean mosfet and get the right voltage to operate it in it linear mode?
I bet just finding and the price of the right mosfet will be more expensive then LM317.
Title: Re: fan thermo switch east simple - temp control
Post by: user1235423643 on August 29, 2016, 05:35:48 pm
hello, thats might have been an idea but

i have a 20-30v output or a 8-6v input boost conv i can tap the power from

using a thermister and a LM317 would give me a voltage drop overhead and a output that will vary on the input.

if my boost conv. is variable then it will effect the lm317

i want to drive a 12v fan 5-12v in speed. so it wouldnt work well i dont think?
Title: Re: fan thermo switch east simple - temp control
Post by: ZeTeX on August 29, 2016, 09:02:41 pm
hello, thats might have been an idea but

i have a 20-30v output or a 8-6v input boost conv i can tap the power from

using a thermister and a LM317 would give me a voltage drop overhead and a output that will vary on the input.

if my boost conv. is variable then it will effect the lm317

i want to drive a 12v fan 5-12v in speed. so it wouldnt work well i dont think?
You have a fairly simple problem that you are trying to over - complicate,
How do you want to connect the thermistor to the LM317?
and if you have LM317 and a thermistor just use the schematic I showed you before.
Title: Re: fan thermo switch east simple - temp control
Post by: user1235423643 on September 03, 2016, 02:44:19 pm
will still give me the same problem