Can pic drive tip41c transistor directly?

[alexan_e]

so you have no base resistor in any of the output transistors to limit the base current?

 

[d@nny]

no
tip122 emitter directly connected to the base of the output transistors. But the base of output transistors and tip122 emitter joint pull down to the bettery negative terminal with 2.2k resistor

 

[alexan_e]

If you don't use any base resistor to limit the current you will have a huge base-emmiter current in the output transistors which can damage them

this is the result of driving TIP122 with a constant current source of 20mA (simulating a PIC output) , 9v power supply


Alex

 

[d@nny]

If you don't use any base resistor to limit the current you will have a huge base-emmiter current in the output transistors which can damage them

this is the result of driving TIP122 with a constant current source of 20mA (simulating a PIC output) , 9v power supply
View attachment 60856

Alex

I have use cd4047 for the same configuration with 52 hertz.
It gives me 300volt ac output
and with no load it was taking more than 10 Amp 13.2 volt dc input

 

[alexan_e]

you have to use base resistor like
12V to 220V converter circuit
or
**broken link removed**

 

[d@nny]

in my schematic where i need to use this
i have three output transistors darlington with pt122
do i need resistance between 4047 and base of pt122 or between the emitter of tip122 and base of outputtranssistors


---------- Post added at 14:16 ---------- Previous post was at 14:14 ----------

in pic TIP41c replaced with TIP122
and three transistors are nec 2750 and there base is pulled down with 2.2K resistance to the battery negative terminal which is not in schematic

 

[alexan_e]

You need one resistor in series with the base of each output transistor, normally you also need a base resistor in the base of the transistor connected with CD4044 but because it is connected as an emitter follower (the load is connected to the emitter) the base current is limited to the amount that is required to give the output current even without the resistor but you can still add a resistor to make sure that the base current will be limited even if the load connected at the emitter requires too much current.

Alex

---------- Post added at 17:02 ---------- Previous post was at 16:41 ----------

you can also consider mosfets for the output **broken link removed**

and
has also many inverter circuits

 

[Tahmid]

Slightly off-topic, but since you are using this for an inverter, why don't you use MOSFETs? You will get much better efficiency, all you need is a good drive circuit. With a drive circuit employing 2 to 3 transistors, you can drive the MOSFETs with very little current. You could even use logic level MOSFETs. Plus, they have a positive thermal coefficient, so they can be better paralleled.

Hope this helps.
Tahmid.

 

[d@nny]

Slightly off-topic, but since you are using this for an inverter, why don't you use MOSFETs? You will get much better efficiency, all you need is a good drive circuit. With a drive circuit employing 2 to 3 transistors, you can drive the MOSFETs with very little current. You could even use logic level MOSFETs. Plus, they have a positive thermal coefficient, so they can be better paralleled.

Hope this helps.
Tahmid.

MOSFET problem when charging battery at high ampere as 30 to 50 ampere
they poped up like popcorn
:???:

 

[vimalkhanna]

This is a fact dependent on the RDon as well as the determination of the surge currents required by the discharged battery .You will need to determine Vds of more than three times the battery voltage .
If the boost charging currents are 30amps ,pl get the Idcf to be >60Amps as the MOSFET does not get channel cooling time like the switchoff period .
The Mosfets must be mounted on the same heatsink to stabilize the temps. and the powershare between the paralleled devices.
A powershare IC for the current balancing may require to be used ,too