Between any pair of test clips. Collector current of 2.50mA. Resistance across reverse biased base-emitter > 60k. Resistance across reverse biased base-emitter < 60k. Drain-source current of 2.50mA. Collector-Emitter voltage of 5V. Thyristor quadrant 1, Triac quadrants I and III. Subject to acceptable LCD visibility. BJT with no shunt resistors.
I have these:
139 142x2 143 144 145 146 147x4 148 149 155 156x2
All Vbes either 690mV or 700mV
Be looking to keep the quad for my 4 channels of Class A. Leo will be getting the pair of his choice. The rest are up for swaps.
I have just ordered the Peak DCA 55 to have a sort through my small stock. Just wondering, if I use it on some 'reclaimed' devices would it indicate they are in good order? I'm thinking of a few early attempted projects that didn't work so I replaced parts whether or not I suspected they were faulty and might still be fine.
The dca will indicate an unknown part if it's broken, so will certainly be useful in that respect. There might be the odd part that is faulty, but indicates OK, if it's only faulty under proper load. One fault I had years ago was a good one. A fuse was reading OK when tested by a meter, but went open under load.
Guys Just remember that these testers use a nuch higher base current than normal to permit the software to correctly identify the type of device being tested. If you check the data sheets for the ON BC549C you will notice that with a typical BC549C that VBE is 620mV at 2mA collector current. Allan found when using his tester with smaller devices like those, due to the high base current used , most of them had almost identical HFE ! When I tested them using the 10uA base current setting of my meter, there was quite a large variation in HFE ! I know which I would prefer to use for matching small signal devices . Alex
Allan found when using his tester with smaller devices like those, due to the high base current used , most of them had almost identical HFE ! When I tested them using the 10uA base current setting of my meter, there was quite a large variation in HFE !
I've not found this to be the case myself, with the devices used in the class A, or bc550c/560c, 639/640. The dca has shown a wide and disparate range of results within the range of the transistor.
I've had a batch of bc337-40 land, as they show a wide range as well, from a quick test.
One for the Poms. ("Beautiful one day, and freezing for the rest ?) ;D
Want "hotter" 2SA1930 and 2SC5171 ? Simple ! Fit a standard 25mm high heatsink (17C/W) instead of the expensive one, or the larger heatsinks. See attached chart for HFE vs. temperature. (click on to enlarge.) Alex