How to choose the transistor and the current limiting resistor of the H-bridge?

Community General Discussions
1

I often see the H-bridge circuit for the 3V motor(Model: 130), VCC is 3V, the transistors are 8050 and 8550,

I have some 6V motors, can I lift the voltage of VCC to 5v and use this circuit to drive these motors?

Is this harmful to the 8050 and 8550?

2

If you actually post a link
If you actually post a link to the circuit, perhaps more accurate help can be available.

3

I click the Insert/edit
I click the Insert/edit image button ,but can not post a link to my schematic, oh my god!!

4

** **

 

|(VCC +3V)

| E | E

R1 1K______B____Q1 8050 Q2 8050_____B____R2 1K

| | C | C |

P2.7(AT89S52) _____| | ____ MOTOR __ | |_P2.6(AT89S52)

| | C | C |

|R3 1K______B____Q3 8550 Q4 8550_____B____R4 1K|

| E | E

(GND)_

5

Logic limit : the P2.7 pin
Logic limit : the P2.7 pin of the AT89S52 probably switches at a 5 volt level, so you should be able to switch both transistors if using a 5 volt supply. The 8550 PNP should be the upper transistor with the emitter tied to +5 volts, and its collector tied to the collector of the 8050 NPN, which also connects to a motor lead. The 8050 NPN should have it’s emitter tied to ground. The 1k resistors are probably fine for protecting the AT89S522 pins. Note these transistors have no flyback diode prtection. For a low current motor, perhaps under 200 mA, they should be fine.

6

sorry, I didn’t remember it
sorry, I didn’t remember it clearly. yes, the upper transistor should be 8550 PNP.