hFE not enuff ?

[squarewave]

hi everyone !

could you please kindly suggest a very simple circuit that i could assemble to measure the necessary parameters of 2sc5200N/ 2sa1943N for the purposes of matching devices?

i have some on order and id like to sort / match them

while in circuit in this amp, the target is a bias voltage 20mV across the 0.3 ohm emitter resistor for a current of 67mA


*i have a hfe tester on my multimeter but i understand that is not enough to provide any "useful/practical" info

much thx

 

[Duke58]

If you buy several from the same lot number, they will be closely matched with respect to hFE.

Matching Vbe is more like what you are asking? Regardless, use this to match Vbe and beta:

 

[PRR]

These are Power transistors.

You need decent Vce to get out of anomalous readings at low voltage. However high Vce will make HEAT in the junction and if not accounted will confuse the results.

I'd wire a jig to force your 67mA no matter what the Vbe is. 15V is enough to swamp variations of Vbe. 15V is also a starter compromise between the 50V these will run at and the different conditions of a very low voltage; a +/-15V supply is common thing on a good test bench. Those big packages will stand the 1 Watt for days, but will get HOT. You will see Vbe drop as they heat up. I am wondering if you need a heatsink and a clamp.

Read the meter and write the number on tag or bag.

Reverse everything for your PNP.

220r 2W is an acceptable part for "213r".

 

[thimios]

Agree, small signal transistors matching devices can't be used for power transistors matching.
You need to simulate real working conditions.