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JochiSt / OpenFlowMeter

Measuring Flow
GNU General Public License v3.0
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Heat dissipation in the PNP transistors #8

Closed JochiSt closed 1 year ago

JochiSt commented 2 years ago

When having a look at the thermal image (sorry for the bad quality) one can observe two hot spots, which are the PNP transistors of the current source. For the first prototype they are SOT23 - quite small and running at a DAC of 768 for a longer time causes them to raise their temperature. 20220311212826

For the next prototype a through hole transistor or a larger package including some cooling area might be a good choice.

JochiSt commented 2 years ago

Replacing the BC856 with a BC558 might be a good choice, the BC558 can withstand 100mA continuos collector current. This should reduce the device temperature further.

JochiSt commented 1 year ago

Replaced the BC856 with BC556 in #10