First time to solder SMD parts, it turns out to be easier than I thought. I have a question about idss matching though.
I've measured the Idss (@12V, as I have no 10V source around) of 40 pieces of BF862, and got some matched pairs. I would like to know if it's better to use a loosely quad-matched for the 2 channels of B1, or 2 closely matched pairs.
Idss of Quad matched: 14.89,14.93,14.98,14.99mA
Idss of 2 matched pairs: 15.81,15.81 and 15.90,15.91mA
I've measured the Idss (@12V, as I have no 10V source around) of 40 pieces of BF862, and got some matched pairs. I would like to know if it's better to use a loosely quad-matched for the 2 channels of B1, or 2 closely matched pairs.
Idss of Quad matched: 14.89,14.93,14.98,14.99mA
Idss of 2 matched pairs: 15.81,15.81 and 15.90,15.91mA
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Thanks Salas, Andrew mentioned the same before. I'll probably stick a small piece of copper foil on them with thermal glue.
@18 degC room temperature and open space, running them @12V and idss for an hour, they aren't even warm. But it's probably very different in the summer, in a small case together with a shunt regulator.
@18 degC room temperature and open space, running them @12V and idss for an hour, they aren't even warm. But it's probably very different in the summer, in a small case together with a shunt regulator.
If they are not even warm then adding 30 degrees of summer heat is only going to make them warm.
150mW on a BF862 with 1mm traces and Pads from the resistor nearby heated to 25°C above ambient. Should be no problem even in a chassis.
If you have this power in a TO92 it runs hotter.
Thanks both
AULT / SL POWER / RESPIRONICS MEDICAL POWER SUPPLY
FYI, the Ault 18V 90W medical power supply model MW116 is now the SL Power MENB1090 also sold as Philips / Respironics 900-150.
FYI, the Ault 18V 90W medical power supply model MW116 is now the SL Power MENB1090 also sold as Philips / Respironics 900-150.
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All of those caps are good choices for a great price.
Thanks for the input.
There are more than a few that do not recommend paralleling many capacitors for a signal coupling duty.
I wonder if mixing lots of different dielectrics will give an average set of parameters that will pass signal cleanly?
what about trying a mix of polypropylene + polystyrene + teflon + polyphenylene sulphide.
Then one could vary the parameters by changing the relative values of each type.
BTW,
what is the objection to using multi-paralleled coupling capacitors?
I wonder if mixing lots of different dielectrics will give an average set of parameters that will pass signal cleanly?
what about trying a mix of polypropylene + polystyrene + teflon + polyphenylene sulphide.
Then one could vary the parameters by changing the relative values of each type.
BTW,
what is the objection to using multi-paralleled coupling capacitors?
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