Originally Posted by Krow
Ultra, is there anyway you could let me know what the current draw at 15V would be?
Or if at all possible make a graph of Voltage vs Current which would help several people out at once.
Don't you think ultrasonic has enough on his plate at the moment ?
He doesn't do this full-time you know he has to works as well....
Well you got the right chart from Heibei.IT but....those charts of theirs are very rough and not the easiest to understand.
Using other charts I did get between 9amps and 10amps so you were right if I needed the figure to choose a supply I would use 9.5 or safer still 10.
You also need to remember that charts are not that accurate BUT are great for ballpark figures and after all since no TEC specs are set in concrete and will vary during operation it is quite a good thing thay aren't too accurate....that's why 9 times out of 10 I wont bother getting a calculator out to work out TEC specs.
For anyone that wants a input power chart for the 300w's.
try using customthermoelectrics instead.
Go to http://www.customthermoelectric.com/...W_spec_sht.pdf
Sorry guys initially I linked to the wrong spec sheet!!
The TEC is pretty much the same it has the same number of couples and the reference temp for the chart is 27ÂºC what is different is the current. The number of couples determines the voltage so as the they are the same the voltage is the same, the current however is determined by the physical size of the couples so it is possible the customthermo unit might have slightly beefier couples. If we change the vertical axis slightly to bring it more in line with the Heibei chart we have a chart we can use.
So instead of starting the axis at 5v change the 5v to 4v and the 10v to 8v etc then the customthermo chart is very close to the heibei one.
Then you have to remember that initial Dt varies with voltage, unfortunately that variation is non linear.
For the sake of a ballpark figure at 75% power you will probably be looking at an initial Dt of 45-50ÂºC down to about 15ÂºC at 20% power the spanner in the works is that when running, the load on the coldside will sway the Dt one way or the other.
Of course once you have the correct (sic
) current so long as you can predict fairly accurately the likely Dt you can use the Q chart to get a rough
idea of cooling capacity at your chosen operating point. N.B. you must use the correct Dt curve.
Like I said you can only work out ballpark figures.... you wont actually know
till you run the thing.
I just thought I might mention because changing the voltages the way i said Skews the graph it will for obvious reasons only be valid for undervolting (which is what I am most interested in.) over say...20v just use the customthermo graph in it's normal form it wont be far enough off to notice. This particular method just happens to work with these units copying it for other spec sheets may not work.Edited by zipdogso - 4/30/10 at 5:39pm