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Kiln Conversion Updraft Downdraft Chimney?


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#141 High Bridge Pottery

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    Joel Edmondson

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Posted 04 May 2017 - 03:38 PM

The data sheet says continuous current of 0.8 amps for the transistor, the one there is 0.1 and I bought a new one that does 0.45 amps. 
 
I am not exactly sure what I am talking about. It looks like it should be happy with 0.8 amps. http://uk.rs-online....istors/6254966/
 

Depending on the fan that transistor might need a heatsink?


One physical test is worth a thousand expert opinions.

 

gallery_23281_871_611.png gallery_23281_871_239.png gallery_23281_871_701.jpg

 
 


#142 Joe_L

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Posted 05 May 2017 - 05:37 AM

Even if its ok for current capacity you still need to watch the power dissipation (voltage drop across the transistor at each speed setting x current at that setting), needs to be less than Maximum Power Dissipation (0.625W in this case). Also watch the temperature, put your finger on it and see its not getting hot at various speed settings.  I'm not suggesting you have a problem, just something to watch out for if failure mid-firing would be a nuisance.



#143 High Bridge Pottery

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    Joel Edmondson

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Posted 05 May 2017 - 07:35 AM

Ok, seems like I might be 3x over at low speed settings  :wacko: 1.8w and it is getting hot, full speed it doesn't get hot and seems to be 0.4w. Confused me at first why low speed made more heat but the transistor is having to get rid of more right?

 

Even if its ok for current capacity you still need to watch the power dissipation (voltage drop across the transistor at each speed setting x current at that setting), needs to be less than Maximum Power Dissipation (0.625W in this case). Also watch the temperature, put your finger on it and see its not getting hot at various speed settings.  I'm not suggesting you have a problem, just something to watch out for if failure mid-firing would be a nuisance.


One physical test is worth a thousand expert opinions.

 

gallery_23281_871_611.png gallery_23281_871_239.png gallery_23281_871_701.jpg

 
 


#144 Joe_L

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Posted 05 May 2017 - 10:25 AM

Effectively, yes.

 

Try something like one of these (not sure what outlet you've got near you, Maplin might have something similar)

http://uk.rs-online....istors/6562037/

http://uk.rs-online....istors/7740711/

 

Spot the hole for a bolt to attach to a heatsink if it gets too hot.






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