bjt tip122-problem

[alain hua]

dear everyone!
i polarize tip122 with power supply 33.6V DC with a resistor 5.1k. but it not working. i measure the voltage, one side of resistor 5.1k connect to power supply is 33.6v and the other of resistor conenct to pin Base of tip122 still OV! anyone have knowledge about this, teach me, plz!thank all.

 

[MikeMl]

Post a diagram of how you have it wired up. What is the emitter connected to? What is the collector connected to?

 

[alain hua]

dear Mr.Mike this is my circuit diagram, thanks for helping!

 

[ronsimpson]

Where did you get this circuit?
What do you want it to do?

 

[alain hua]

i get it from electronic balance, Mr. Ron!so...!

 

[ronsimpson]

I have used this IC many times and I don't know what you want to do.

 

[alain hua]

OH!i have problem with tip122, it not working. like i wrote at the first time!

 

[ronsimpson]

I very much understand that it is not working.
Please explain what it should be doing when it is working.
The circuit you drew (I think it should do nothing). It is doing what I think it should do.

example: Put a car tire on the ground. Add the rudder from a boat. Tape your cell phone to the tire. Add the door handle of a house. Then in post #3 say 'it is connected to something (3525A)'. But I am not going to say what it is connected to. "IT IS NOT WORKING" I know it is not working! These things all work when used correctly. These things usually do not work when used in a strange way.

If I knew that you want.....car, boat or house??? Maybe you are making a small pile of parts. In that case the parts are working just fine.

What is the 3525 doing? (probably a switching power supply) Maybe not.
I do not know what "not working means". I do not know what "working" means. I do understand you have 33.6 volts and you don't like 0 volts. What voltage do you like? (12.98)?

 

[audioguru]

You have the secondary winding of your transformer shorting the +33.6V to ground.

 

[alec_t]

Wired as shown the TIP122 will just behave rather like a diode. I doubt that's the intention.

 

[4pyros]

Maybe the collector should be tied to 33.6 volts and the top of your transformer to the base resister only.

 

[alain hua]

if tip122 is "on" it will provide the power supply for ic 3525A, and ic 3525A operate, control Irf631. but when i provide the power supply 33.9V for tip122 by R=6.8k, tip122 still silent, the voltage = 0v, the current = 0v. i mean if tip122 is "on" the voltage between pin Base and pin Emiiter of tip122 must be 0.6v. im trying to find out the mistake of this part!because this is the power supply block of the big circuit. the big circuit is control the lcd & the keypad like the picture i attached.thank all!

 

[ronsimpson]

I don't see how you can have 33 volts D. C. across the transformer.
Have you removed the transistor and checked to see if it is OK. Perhaps the B-E is internally shorted.
Do you have a ohm meter. Many new meters have a diode test mode. The B-E should look like a diode. (also the B-C)

 

[audioguru]

I corrected your circuit but because its input is AC from a transformer then it swings negative which is bad and swings positive.

 

[4pyros]

Do you have a load on the transistor for your testing?

 

[alain hua]

yeah! in the original circuit the bjt is D1293M, it was burn, i cant find D1293M at my location then i replace it by Tip122.
i checked tip122 diode between B-E, still good. i attach here datasheet of D1293M & TIP122. Plz! remind me if have any problem when i choose tip122 to replace d1293m.
do you think the transformer have problem? i have another big ciruit provide the power supply 33.9v to the diode brigde then from diode brigde go to the transformer, i think maybe the isolation transformer is protect to.!
thank!

 

[alain hua]

Mr.Audioguru!by your mean, 33v dc from transformer will connect direct to Base of tip122.collector and base of tip122, are connect to transformer.
sory, but maybe the voltage too hight!?will tip122 destroy?

 

[audioguru]

Nobody makes a "D1293M" but maybe you have a Japanese 2SD1293M? It is an ordinary NPN transistor not a darlington transistor.

Your schematic and your description of the circuit makes no sense.

 

[audioguru]

Mr.Audioguru!by your mean, 33v dc from transformer will connect direct to Base of tip122.collector and base of tip122, are connect to transformer.
sory, but maybe the voltage too hight!?will tip122 destroy?

The output of a transformer IS NOT DC! Instead it is AC. Maybe your transformer output is rectified by a rectifier bridge then has a filter capacitor? Then it can produce +33.6VDC.
Your schematic was completely WRONG. The transistor was doing almost NOTHING.

 

[alain hua]

thank for your advice Mr.Audioguru! about Bjt, that is i my mistake!i will find another bjt accordingly.
And about transformer, it is PULSE TRANSFORMER have 12pinout, with 4 pin group. i measure the resistor between the pin in the group, it equal 0.6ohm. i think it should be deference about resistor.?
thank