H bridge

[moonstreat]

I would like to post a schematic of a H bridge, so that I could control the direction of rotation of my 2 DC motor that I have in my car ..

I appreciate everyone's help. . .

 

[Grossel]

Just search for it on the web. You'll easilly find it.

Search link:
h bridge - Google-søk

 

[Mike odom]

I would like to post a schematic of a H bridge, so that I could control the direction of rotation of my 2 DC motor that I have in my car ..

I appreciate everyone's help. . .

for an example, see L293 @ Digikey.com 497-2937-1-ND and pull the data sheet, is good for 600mA per channel. It has two channels (for two motors)...

if you need more current, see thumbnail. This was used on a Linear actuator for a variable geometry turbine used for more power to compensate for all the armor they started putting on HumVees... I forget the current rating, where ARE my old design notebooks??!!?? The four darlingtons are the driver transistors, the other ones are for two input control and to make sure both sides don't engage ath ehe same tsending VCC to GROUND....

 

[moonstreat]

which they think is best??

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OR

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[Mike odom]

which they think is best??

**broken link removed**

OR

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The top one won't work unless you use high side drivers for the top... your top gate voltage has to go above the collector voltage to turn the transistor on into saturation.

I like the bottom one as it uses FETs and allows for 2 pin control. You have to size/heatsink your FETs for the current you need on the motor.

 

[Hero999]

The top one will work, it'll just have a high voltage loss.

I'd modifiy the bottom one so Q4 and Q6 switch the Q3 and Q5 so Q1 and Q2 can be omitted.

 

[audioguru]

The top one won't work unless you use high side drivers for the top... your top gate voltage has to go above the collector voltage to turn the transistor on into saturation.

You are very wrong. It uses P-channel Mosfets as the high side drivers, not N-channel.

But it does not show a supply voltage so it might not work.

 

[Mike odom]

You are very wrong. It uses P-channel Mosfets as the high side drivers, not N-channel.

But it does not show a supply voltage so it might not work.

A TIP120 is a P channel MOSFET? I think not... the data sheet I read said bipolar NPN Darlington
maybe I should be more clear...
the top SCHEMATIC will not work... they may turn on, but if you don't put it into saturation, all voltage dropped across the transistor will be dissipated as heat and it will burn up

 

[Mike odom]

The top one will work, it'll just have a high voltage loss.

I'd modifiy the bottom one so Q4 and Q6 switch the Q3 and Q5 so Q1 and Q2 can be omitted.

so you'd turn on Q4 and Q6, and have them turn on Q3 and Q5 instead of the other way around? Clever... very clever...

did you see my H bridge schematic... I added two more transistors to ensure both sides don't come on at the same time... how can we do that to *your* modified circuit???

 

[moonstreat]

I wanted to put is 12V output, none of these schemes is for what I precizē?

What will the circuit, operating without burning components??

 

[Mike odom]

I wanted to put is 12V output, none of these schemes is for what I precizē?

What will the circuit, operating without burning components??

moonstreat, that's why electrical engineers are MATH MAJORS... you picked the 'scheme'. Look at your schematic number 2 (bottom one)... see the motor in the middle? If you attach 12V to the pin at the top (circle), and turn on one channel, it will deliver +12V to the motor. The polarity of the +12V depends on which channel you turn on. On channel delivers +12V to motor + and ground to motor -, causing it to go forward. The other channel does the opposite... delivers +12V to motor - and ground to motor +, causing it to go in the reverse direction. Whether or not the circuit burns up depends on how much power it has to dissipate which depends on how big the motor is. Dissipating power causes heat, or more specifically, a temperature rise above ambient. So you have to know how much power you are delivering, how much will be dissipated in the control devices, and the ambient operating temperature. Then you look at the thermal characteristics of the driving transistors, the duty cycle you're trying to run the motor at, and determine whether or not you need a heatsink and/or how big it has to be, or if you can rely on convection cooling or have to add a cooling fan/system, or reduce your duty cycle. These are all variables that differ from app to app, depending not only on the motor you are driving, but also the components you pick: transistors AND even the resistors, and the voltages you are running them at. So that is why when ask for help, the first thing we do is ask you for more info...

 

[moonstreat]

I made the steak, do not know what to do ... : \

 

[Hero999]

Here's my idea.

The diode provides shoot through protection.

This circuit has an absolute maximum voltage rating of 20V and is only good at fairly low frequencies. Zeners diodes or extra resistors need to be added for higher voltage operation.

 

[moonstreat]

Hero999 where do I turn on the engines?

 

[Hero999]

What do you mean?

Rl means the load resistance, replace it with the motor.

You might need some back-EMF suppression diodes across the MOSFETs but the parasitic diodes could be good enough.

 

[moonstreat]

**broken link removed**



I do not understand, I'll start the motor in series with the resistance RL?

 

[kinarfi]

What FETs are you using, how much current does the motor draw when hooked up directly to the power supply?
Kinarfi

 

[moonstreat]

my motor is 12V and consumes 150mA

 

[kinarfi]

my motor is 12V and consumes 150mA

What FETs are you using

 

[moonstreat]

What FETs are you using

I do not know! why I came to the forum go out on a circuit pa my project!