TIP 127 Power transistor

[bushygs]

I ma using TIP 127 to switch on and off the power load based on the input voltage, i.e. when the voltage is above 10.50v then the power is supplied through TIP127, when it drops below the said volt the TIP switch off. Emitter is connected to input volt base is connected to a Resistor & Zener combination 10.50v and collector to out put. I am able to get the get the TIP to switch on and off however the not able to get the current say if the input current is 500mA out put is only 5-10ma.
Can any one explain how to use the TIP to get the desired current output?

 

[Prototyp_V1.0]

Can you draw a schematic (just a simple) and upload it?

 

[keith1200rs]

Yes, the description stumped me as well!

Keith

 

[bushygs]

Yes pls find attached the schematic

 

[keith1200rs]

You are not going to get much base current through R2. Without base current you will get very little collector current. It isn't a great circuit principle for what you are trying to achieve, but you could try something a lot smaller for R2. - say 100 ohms.

A better circuit would need more parts.

Keith

 

[bushygs]

Thank you, it is part of a larger circuit, it is used in UPS with auto cutoff for battery protection. i have attached the detailed schematic including the explanation, can you help now pls

 

[keith1200rs]

I just looked up the TIP127 and it is actually a darlington so the symbol is incorrect. Also it will not need the low value base resistor I mentioned earlier. What voltages are you putting in to the circuit when you are expecting it to switch and what load do you have? With a 10.5V zener you will need at least 12V on the emitter to turn the transistor on because of the 1.4V or more across the base/emitter.

Keith

 

[bushygs]

I would like to use this circuit to power a 12V 500mA circuit. And the battery I am using is 6v 5Amp *2 batteries = 12V battery. e\
When the battery is in use and to protect the battery from deep discharge I would like to use this cut off circuit using TIP 127. The Emitter of TIP 127 would get 12V 1Amp as input and the output at collector can be 12V 500mA. When the battery reaches 10V the zener stops conducting and the base of TIP would not be biased and the emitter cuts of supply to collector. If am wrong correct me with a schematic pls

 

[Prototyp_V1.0]

Yes pls find attached the schematic

Can you please upload a normal picture, so people that doesn't have ms/open office installed also can see the picture?

PNG format would normally be the best choice for schematics

 

[keith1200rs]

The transistor will stop conducting at around 12V, I would have thought, not 10V. Try a higher input voltage to determine the cutoff voltage, or try a 9V zener.

Keith

 

[bushygs]

The Input voltage is around 12.5 to 13 v and when the volt is appiled to emitter of TIP 127 the base is giving an output (how) of 11 volt with sam Amps. even after using a 100 oms or lesser resistor (though the Zener conducts at 11 volt).

Added after 7 minutes:

OK shall try to upload the image in PNG format

 

[keith1200rs]

As I mentioned earlier, as the TIP127 is a darlington, a lower value resistor isn't required as I first thought. Could you measure the exact voltage on the base, emitter and collector and post it. Also, what load are you using? You say that you only get 10mA out, but if you are using a low resistance load than would suggest that the transistor collector must be at a very low voltage.

Keith

 

[bushygs]

Emitter input volt 12.7v 450mA
Base (before connected to Zener ) 10.8 V 450mA
Collector (before connected to Zener to Base) Nil
Collector (when Zener is connected to Base ) 12.7 V 20mA
Resistor- Zener Combination output is 2 V 20ma

 

[keith1200rs]

Check your transistor connections - they seem like the measurements of a transistor connected incorrectly.

Keith

 

[bushygs]

TIP 127 pin config
Pin 1 = Base
Pin 2= Collector
Pin 3 = Emitter

hope i am correct

 

[keith1200rs]

Assuming you are looking at the device the right way round, that is correct. However, your measurements earlier said 10.4V on the base when it wasn't connected and 450mA to the load. With the base disconnected the base voltage should be the same as the emitter due to the resistors in the device and the current should be zero. Have you actually got a TIP127? Could you have blown it?

Keith

 

[bushygs]

Yes front view config is what I had mentioned, shall rework on the voltage and current on all the three pins and get back to you thank you very much

 

[bushygs]

Tested the TIP 127 front view pin 1 base pin 2 - collector pin 3- emitter, input volt 12v 1 amp. Base 12v .8 amp, Collector - 0v. when base pin is activated, the collector output is 12v and .07 amp.