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# Looking for H bridge control circuit

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#### attrib

##### Junior Member level 1
tip126 h-bridge

I need the control circuit..... so if u have and idea...... an interesting article that u want to share....... don't doubt to email me... I know that in the market exist several CI that can do the job..... but i would like to do it in a analog form.
thanks
Atte.
Attrib

H-Bridge

Its qiute simple -> you have only take care of the bias voltages of the used transistors.

so if you are using TIP121 and TIP126 as the complementary transistors, the bias voltage will be about 1.4V (because thei are darlingtons) -> so you will need an opamp which reaches this or you can use a digital device which drives the bridge.

i built a pwm temp-controller with this type of transistors

Re: H-Bridge

Do u have the diagram?? i am really interested about your desing
I hope that u can help me.

Atte.
Attrib

A standard H-bridge uses 4 switches (transistors usally). Two high side and two low side. For easy of implementation, use P and N channel FETs. If you use just N channel, unless you use a biasing voltage, you will get shoot through and burn them up. Try looking at the L298N

h bridge

A classical way to drive an H-dridge is using a PWM signal & a SIGN signal.

if your bridge looks like this:

VCC
HL HR
|-M-|
LL LR
GND

HL : P mosfet
HR : P mosfet
LL : N mosfet
LR : N mosfet

when SIGN=1 (HL = LR = OFF )

PWM - 0 - 1 - 0 - ...
HR & LL -OFF-ON-OFF-...

when SIGN=0 (HR = LL = OFF )

PWM - 0 - 1 - 0 - ...
HL & LR -OFF-ON-OFF-...

It's one solution before others. It depends on your needs.
rem : If your load is inductive : don't forget to add fast-recovery diodes for each transistor.

Good luck

K2d2

### K2d2

Points: 2
They have h-bridge ic's avaiable.. search on google

h bridge

Is only for security....
I used a non lineal load in this case the motor...... so again Thanks.....
Atte.
Attrib

Re: help with H bridge......

Yes you can bulid own H bridge.

But I suggest National LMD18200.

Re: h bridge

when SIGN=1 (HL = LR = OFF )

PWM - 0 - 1 - 0 - ...
HR & LL -OFF-ON-OFF-...

when SIGN=0 (HR = LL = OFF )

PWM - 0 - 1 - 0 - ...
HL & LR -OFF-ON-OFF-...

It's one solution before others. It depends on your needs.
rem : If your load is inductive : don't forget to add fast-recovery diodes for each transistor.

Good luck

Hi samsuffy!

I want to control on my H-bridge circuit, with NPN and PNP transistors, as you have described but I have no idea how to implement it. please could you attach the connection diagram for the control circuit? I have tried many different options now and I can't seem to get it right.

Its good to know that there are people out there who know what others need to know. All one must do is ask.
K2d2

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