Continue to Site

# Can bc557 and bc547 be used to compose of h-bridge ciuruit?

Status
Not open for further replies.

#### xmli1976

##### Full Member level 1
bc547 h bridge

Can bc557 and bc547 be used to change current direction of motor in h-bridge instead of darlington transistor or cmos?
It's a small motar .it uses 5vdc.

#### olemp

##### Full Member level 1
bc547 current limit

probably you can not.
just measure current of the motor with load-force shaft of the motor with something -.........
and compare with the max transistor collector current......

### xmli1976

Points: 2

#### crazyduck

##### Full Member level 4
h-bridge bc337

Hi,
Yes you can if your continuous current motor is less than 100mA.
CD

#### kot_b

bc557 bc547

I can advice try make something like darlington with BC5xx and something more powerfull - BD135 and etc.
Motor offten have quite big inrush current, so you have to affraid of it.

### xmli1976

Points: 2

#### xmli1976

##### Full Member level 1
current limiting with bd135

I used a 78l05 as a power supply which can supply 100ma current only,and the motor worked fine,so I think bc557 and bc547 can meet the circuit.

#### manu

##### Full Member level 3
bridge h bc547 bc557

Use BC337 ( to92 ) or BD135/136 ( to126) instead use BC547, they can load 1000mA. ;-)

Regards,

Manu

### xmli1976

Points: 2

#### bimbla

darlington with bc547

Yes go ahead and use it.

If you can, use BC517 and its PNP counterpart.

bimbla.

#### manu

##### Full Member level 3
h-bridge bc548 bc557

bimbla said:
If you can, use BC517 and its PNP counterpart.

Yes, of course, BC517 is a High Hfe bipolar transistor ( hfe = min 30000 ) whereas BC337's hfe is 'only' 100 > 800. The max current of BC517 is equal than BC337's

Regards,

Manu

#### bimbla

h-bridge with bc 547

BC516 (PNP) and BC517 (NPN) are small signal, complimentary darlingtons.
ICmax = 500MA, Vdc max = 30Vdc and hfe = 30,000.

The advantage of using darlingtons is that it will not overload the driver stage since it has high hfe and therefore will require small base drive and also the switching will be more reliable because the device will turn on at NOT 0.7V but at around 1.4V, therefore that much more noise immunity.

I hope that his helps.

bimbla.

#### trigger74

##### Member level 4
bc547 bc557

xmli1976 said:
I used a 78l05 as a power supply which can supply 100ma current only,and the motor worked fine,so I think bc557 and bc547 can meet the circuit.

78L05 is not limiting the current...... and motor usually draw at least approx. 200mA at running and a startup current at least 500mA or more (depends on the load).

Be careful that the 78L05 and those general purpose transistor may get a little bit hot!

### xmli1976

Points: 2

#### platonas

##### Full Member level 3
bridge h bc547

I used a 78l05 as a power supply which can supply 100ma current only,and the motor worked fine,so I think bc557 and bc547 can meet the circuit.

78L05 is not limiting the current...... and motor usually draw at least approx. 200mA at running and a startup current at least 500mA or more (depends on the load).

Be careful that the 78L05 and those general purpose transistor may get a little bit hot!

Also, have in mind that, any capacitors after the regulator can supply current for short duration but at a level that can destroy the transistors. Motor's starting current especially with load is about 3-10 time the running current. With a large electrolytic for decoubling the transistors will fry.

The 78L05 limits the current to something little bit more than 100mA.

And, as specified by the previous poster, mind the head produced on all active components.

Points: 2