How to TEST this beast?

[Guest Kasamiko]

Hi,
Sorry for this DUMB question..but I mean it..
How can I test this thing DTA124E, efficiently using an ordinary VOM.. ???
I supposed there must be areading between Base and Emitter since in the diagram, BASE and EMITTER is connected with series resistors about 22k each..


rhonn  ;) ;)

343-21799-0-DTA114ERLRA.pdf

[prateeksikka]

IN MY OPINION THE CONVENTIONAL CONTINUITY CHECK IS DIFFICULT HERE
MAY BE IF YOU HAVE EXTRA STOCK!!!!!TRY  CAN GO FOR IT OUT APPLYING SOMEWHAT HIGHER VOLTAGE B/W BASE AND EMMITER.OR U CAN MEASURE THE DEVICE GAIN BY CONNECTING SUPPLY AND A few VOLT SIGNAL(mV SIGNAL WILL I GUESS BE INSUFFICIENT TO TURN IT ON)
PRATEEK

[audioguru]

Hi Rhonn,
Does your multimeter have a "diode test" function where it measures the DC voltage across its probes when it supplies a low regulated current from a few volts? Or just an ordinary ohmmeter with at least a 1.5V voltage? Then you can measure if the transistor works, something like what Prateek said:
1) Positive probe to C, negative to E. With the input open the transistor should not conduct. Connect the input to E and it still should not conduct. Connect the input to C and it should conduct much more than only 44K ohms.
2) Negative probe to C, positive to E. It should not conduct if you connect its input to either probe but you will measure 44K ohms with it connected to C.  ;D 

[prateeksikka]

hi audioguru!
i think that is where his misery lies,even if his meter has a diode switch or even if it has resistance switch,i think multimeter battery will not be strong enough to circulate ample current through 44k resiatance!! an external source may be required
prateek

[audioguru]

Hi Prateek,
If the ohmmeter has a 1.5V battery and the transistor's base requires 0.5V to conduct a bit as shown, then the top resistor will have a current of 45.4uA and the base will have a current of 27.4uA. With its shown current gain of only about 20 at this low current, its collector current will be about 426uA. It will be similar to a 3.5K resistor, much lower than its 44K series'd resistors.

My DVM uses 0.4V for resistance measurement but 4V for diode test. So it couldn't test this or any other transistor's conduction on its resistance measuring function. But if this transistor is good it will measure about 1.0V on its diode test.   

[Guest Kasamiko]

My VOM has a diode tester..when measuring diodes and transistor I usually got about 0.5 to 0.6 volts for good junction but with part I can't get a good reading.  :o
I tried reading the the BASE and Emitter with Ohmmeter and I got an accurate 22k Ohms reading but BASE to COLLECTOR is nothing..
Maybe a simple circuit that this thing will function as SWITCH might help.., ;D

rhonn  ;) ;)

[MP]

Quite frankly Rhonn,
If I had a doubt, I would just replace it. They are about 8 cents each in qty (large qty), but On-Semi will send out as many as 25 free samples for just the postage. You can't buy many labor hours for this amount of money. Best to put your labor elsewhere.
Just my 2 cents  ;)


MP

[Guest Kasamiko]

Quite frankly Rhonn,
If I had a doubt, I would just replace it. They are about 8 cents each in qty (large qty), but On-Semi will send out as many as 25 free samples for just the postage. You can't buy many labor hours for this amount of money. Best to put your labor elsewhere.
Just my 2 cents