I've connected the circuit as you said but there are no voltages at any transistor , I think that 50 k to the base of BJT is too much?

That's definitely not the problem.
I hate to say this, but how about an L293D?

 

I've connected the circuit as you said but there are no voltages at any transistor , I think that 50 k to the base of BJT is too much?

Even when you apply 3.3V to the 50k resistors?
Not likely the problem but you can try reducing them to 10k's.
Double check all your connections, particularly the DGS connections on the MOSFETs.
Post the voltages at all three terminals for all four transistors.

 

Even when you apply 3.3V to the 50k resistors?
Not likely the problem but you can try reducing them to 10k's.
Double check all your connections, particularly the DGS connections on the MOSFETs.
Post the voltages at all three terminals for all four transistors.

Okay here are the connections and it seems like fine , you might check it too so we can be 100% sure. And there are no voltages across any of the resistor , guess FETs are 100% in cut off region,

That's definitely not the problem.
I hate to say this, but how about an L293D?

Woke up today in the morning and 4 packages came from china today( like they knew it's my birthday) , and one of them is motor drive shield shield http://www.ebay.com/itm/221924203360?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT with 2x L293Ds,

I took away one of the L293Ds since I am still waiting for my arduino to arrive , and made this circuit it works like a charm.

Checked the circuit on the datasheet:
http://www.ti.com/lit/ds/symlink/l293.pdf
It has diodes built in so I don't have to add any.



Still I added two capactiors in parallel with L293D outputs of the motor , connecting positive electrodes to pins 14 and 3 is that okay?
Wonder if I need any extra components.
Actually I am trying to build a robot , but I can't get that remote control via IR working but I guess I will make another thread about that problem.

 

Still I added two capactiors in parallel with L293D outputs of the motor , connecting positive electrodes to pins 14 and 3 is that okay?

Does this mean that you have connected capacitors across the motor? If the capacitors are electrolytic, and you want to run the motor in both directions, then it is definitely not a good idea and could result in explosive destruction of the capacitor.

 

See transistor ZTX690A Beta~1000, Ic=2A, P=1W TO-92

 

Does this mean that you have connected capacitors across the motor? If the capacitors are electrolytic, and you want to run the motor in both directions, then it is definitely not a good idea and could result in explosive destruction of the capacitor.

I used ceramic ones, as you said electrolytic can explode , yeah prolly not a good Idea.
I guess there is no need for adding them , since if voltage is cut from a motot it has a path via ground to discharge the energy stored in the inductance of armature coil.Again do I have to add extra components to my circuit?I dont want my msp430 getting fried.

Those ZTX690A are pretty expensive 4 USD each.

This is the board that was originally in the car toy, I think this chip is for radio remote control since there is a coil and capacitors,some RLC circuit I guess.
They used BJTs for motor control I dont see any FETs maybe one of them can be used if they are still funcional.

 

I guess there is no need for adding them , since if voltage is cut from a motot it has a path via ground to discharge the energy stored in the inductance of armature coil.Again do I have to add extra components to my circuit?I dont want my msp430 getting fried.

The diodes are there to catch any spikes. You might add small capacitors on the motor to reduce radiated RF interference. They should be on the motor terminals not on the circuit board.

 

ZTX690B cost $0.89 (DigiKey) and simple circuit!

 

ZTX690B cost $0.89 (DigiKey) and simple circuit!

Thank you , I will definetly check this site , they have a site for my country too , I looked at ebay and those transistors were really expensive there.

The diodes are there to catch any spikes. You might add small capacitors on the motor to reduce radiated RF interference. They should be on the motor terminals not on the circuit board.

Well how should I add them since motor is changing directions , or it doesnt matter?

 

Well how should I add them since motor is changing directions , or it doesnt matter?

http://www2.etown.edu/wunderbot/DOWNLOAD/NPC_T74_Motors/Application_Note_Motor_Noise.pdf

 

http://www2.etown.edu/wunderbot/DOWNLOAD/NPC_T74_Motors/Application_Note_Motor_Noise.pdf

Thanks

 

Hello it's me again ,
I would like to ask is there alternative for L293D it has huge voltage drops for example I need to connect 10 V power supply to Vcc1 and Vcc2 in order to have voltage drop around 4 V at each motor guess it's because it's really old technology.

 

You are driving just one motor?
You can parallel connect both halves of the '293. This is pretty easy as the links between pins go straight across the chip.
http://www.positron-libre.com/archives/moteurpasapas/l293e-applications.pdf
"The outputs of an L293 or L293E can also be paralleled - in this case too channel 1 must be paralleled with channel 4 and channel 2 with channel 3."

 

You are driving just one motor?
You can parallel connect both halves of the '293. This is pretty easy as the links between pins go straight across the chip.
http://www.positron-libre.com/archives/moteurpasapas/l293e-applications.pdf
"The outputs of an L293 or L293E can also be paralleled - in this case too channel 1 must be paralleled with channel 4 and channel 2 with channel 3."

I am driving 4 DC motors with 2x L293Ds

Those are the motors:
http://www.ebay.com/itm/221891182052?_trksid=p2057872.m2748.l2649&ssPageName=STRK:MEBIDX:IT

Those are some tehnical specification about the motors


I am looking for another chip.

 

I am driving 4 DC motors with 2x L293Ds

Ah, OK, paralleling won't help then.

 

Ah, OK, paralleling won't help then.

I read that also L298ns have the same problem, do you have any suggestion on some good chip or I am doomed to make my own h bridge.

 

You could just raise the supply voltage to compensate for the voltage drop. That might be easier than starting from scratch.

 

You could just raise the supply voltage to compensate for the voltage drop. That might be easier than starting from scratch.

Guess I will need to implement 15 V batteries when robot will be done for powering L293ds.