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DIY Thermal LPM for under $50

ARG

ARG

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4.7k will work as a replacement for the 5k resistor. You may want to get a multi-turn pot for that 10k pot.
 





Kalmito

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THX!

I have LM358N
I have to connect 6 and 7 pins in GND or not, because here is
not connected:

easylpm.PNG


And here is connected:

34058d1313332594-diy-thermal-lpm-under-50-mmeasylpm1.jpg




ARG said:
4.7k will work as a replacement for the 5k resistor. You may want to get a multi-turn pot for that 10k pot.
Click to expand...
 
Zeebit

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You could leave it unconnected. Pins 5 and 6 are the inputs of the second opamp. You could also ground them to ensure nothing comes out the other end.
 
Kalmito

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but I dont need second opamp , right !?


Zeebit said:
You could leave it unconnected. Pins 5 and 6 are the inputs of the second opamp. You could also ground them to ensure nothing comes out the other end.
Click to expand...
 
ARG

ARG

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Tie the inverting to the negative supply, and the non inverting to the positive to supply to reduce noise, or tie non-inverting to common an tie inverting to the output.
 
Last edited:
H

honeyx

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Zeebit said:
You could leave it unconnected. Pins 5 and 6 are the inputs of the second opamp. You could also ground them to ensure nothing comes out the other end.
Click to expand...

Leaving the secound opAmp unconnected or grounding it will cause noise under both circumstates. There is a proper way to terminate unused OpAmps.

1957Fig01.gif
 
Last edited:
Kalmito

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I dont understand this....

this will be good ? :
5767-lpmampv2.png




honeyx said:
Leaving the secound opAmp unconnected or grounding it will cause noise under both circumstates. There is a proper way to terminate unused OpAmps.

1957Fig01.gif
Click to expand...
 
H

honeyx

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Where is the problem? The first OpAmp should be conneced like in the pic you quoted but the secound terminated like on the pic I attached.
 
Kalmito

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In this picture please write me OpAmp (ic2 lm358)
Used pins... because here is dont writed :

1957Fig01.gif



honeyx said:
Where is the problem? The first OpAmp should be conneced like in the pic you quoted but the secound terminated like on the pic I attached.
Click to expand...
 
Last edited:
ARG

ARG

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honeyx said:
Leaving the secound opAmp unconnected or grounding it will cause noise under both circumstates. There is a proper way to terminate unused OpAmps.

1957Fig01.gif
Click to expand...

That is the best option, but it's not entirely necessary for this.
 
Kalmito

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Everyone else says, now what I do? Please have someone draw a shematik that is functional... :undecided: I'm clueless...
 
Last edited:
ARG

ARG

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Kalmito said:
Everyone else says, now what I do? Please have someone draw a shematik that is functional... :undecided: I'm clueless...
Click to expand...

Connect the unused OPAmp like honeyx says, only a couple extra resistors.
 
Kalmito

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kVZo3i.png


5,6 pins connected to GND witk 1K ,1K resistor... ( green ) , 7pin not used!
Will be good ?
 
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