Tronic's DIY dual Mosfet H-bridge (DSMhb)

Hi,
Today i read out this whole topic looking for the max acceptable temperatures for the IRLZ44N and IRF4905.
It is not the first time I search this answer. I went to google and nothing!
I am using one standard fan and temperature go higher than 65ºC with wiper motors running.
Things are working and there is no short circuit !
Is this ok?
regards!

Hi, if I turn one pot all way to one side and let the wiper running few minutes is the same as PWM1 tied up ?
Because that is what make my mosfets hot!
regards!

Hello Rafael, I think that all is well.
In my case, after 1 hour of play the temperatures do not exceed 70 ° C (I think it's important not to exceed 90 ° C on any of the mosfet). I use an extraction fan at the top, placing a second fan (pump) in the side. The tests were performed at an ambient temperature of about 20 ° C.

regards
micma80

The MOSFET datasheet will tell you absolute maximum ratings. It will also give you a graph that shows current passing through them will decrease as heat increases -> less power to the motors.

Absolute maximum ratings should be around ~175°C, so 70°C is still ok, although it is not operating as it should . I have used IRFZ44N MOSFETs in other circuits only higher currents, average temperature didn't exceed 40°C, without any heatsinks.

i Just fried my irfz44n last night on stress test...overclocking my pic16f1937 at 40mhz. 50khz pwm.....puffff.

Hi, today I finally assembled everything together (cockpit+boards+software) but my 74HC08 chip is gone again. (to buy it again I have to travel 70Km so better buy 10 of it!!!)

It is the third time this happens so I am wondering from where come the problem.
If anyone can help telling me if the most probable source of the this problem is AMC/ATmega sending bad quality signals or the HB itself would help alot!

My best bet is that I have bad quality resistors on both boards. Here some pics:


Tip: When I measure the signals from the cable that come from AMC all seems to be fine. (M1 IN1, M1 IN2, Vcc, Gnd, etc.)

Note that I know that it is impossible for you to tell me for sure if you are not here so that is why I ask for the MOST PROBABLE SOURCE of the problem :

regards!

have you try pololu motor driver before? :yes:

Hi there, my set up is made from steel outside and aluminium inside. The inside frame is still quite heavy though. I use 2 wiper motors second hand from a auto wreck yard for $15 each. I just looked for large size ones from a large passenger car. It does come down to pivot point balance as I found out and with lots of advice and help. I also run pololu jrk 12v12 motor drivers.

2dof-wiper-motor-sim-continuing-t3048.html here is what I have done so far, refer to the end of the posts for action.

Hi again! :rofl: (laugh for not to cry)

I apologize and say that the 74HC08N was not the problem. It seemed the problem because of a damaged mosfet that was interfering on my readings. I did not realize that it could do this backwards to the chip!

After troubleshoot every area of my HB I have to say that M2 (motor2) is working 100% fine.
But, M1 is working only in one direction.
The weird is that everything was working fine before.

Here one picture that speaks for itself:


Any idea of what components do the job for the direction I talk about?
Tip: After I replace the damaged mosfet, the 74HC08N sends the voltages very fine for both directions and both motors!

regards!

it could be anything.. :yes:

Ok guys I am in the process of trying to order all fo these parts but I have a serious problem. When looking for parts there are slightly different versions of these parts. For example..... BC546 TO-92 There are different versions how do I know what version to get? If I buy one that says exactly BC546 TO-92 do I not have to worry about the volts or mA also on the picture of the part there is a W 67 I think well some have a different number like W 53 does that matter?

Also will any of the components need to be changed in order to use wheelchair motors. They are 24V DC I am not sure on the amps yet but they could go as high 15-20 amps altough I don't think they go that high. I haven't actually recieved them from ebay yet. Any help would be greatly appreciated since I am very frutstrated because I don't understand the ins and outs of electrical stuff. I am at a standstill and do not know how to continue. :dntknw:

TO-92 is the package shape. Its not too much important the difference in mA, if they have any, they are used only to drive the gate of the mosfets (turn the mosfets ON & OFF).

Thanks for the quick responses guys. Once I get all the stuff in the mail i'm sure I will have many more questions.

Got a question on the battery topic. My motors are 24v So will I need to batteries together to get 24v? Also should I worry about what type of deep cycle battery I get? There are all different ratings. CCA cold cranking amps are over 700 on some should I take that into consideration?

Here is one battery I found. Do I need it that big or can I go with smaller one? http://www.car-stuff.com/carparts/toyot ... 1080402181

Well... Its a little big ... Maybe something rated between 100 -120 Ahr ...

I think I saw 24v batteries before...

Hey guys got another question. I'm getting ready to try and print out the pcb layouts so I can make my pcb's. How do I know the size of the boards? I dont see any dimmensions. Some printing programs adjust the size of the image to fit the page so I am not sure if there is a specific file to print out and whatever comes out is the proper size? I am thinking I just use the File: Dual_Simple_Hbridge_1_2B then from that do I use the first image the one with black traces and the board is white so when I print it out on the laser printer it will put the ink where only the black lines are? What is the second image for? It links the same but the colors are just switched. Thanks guys and sorry again for my greeness

OK I think I figured it out. I think I should use the file labeled Dual_Simple_Hbridge_1_2B_bottom

Because its separate and i'm assuming it will be the right size Would be nice to know the length and with dimensions though just for peace of mind.

Hello guys I recieved my motors. I have called everywhere and searched the interwebz high and low but can't find much info on them they are made over seas. I think the stall amps can go as high as 40 amps i think operation will be near 20amps just by guessing by other motors ive seen. These are 24volt DC wheelchair motors. I'm going to take them to my fathers house later today he might be able to figure out the specs on them he knows a lot about electronics so I don't know if its possible to extrapolate the volt and amp draw by using some equipment. So my question is will this H Bridge run these motors? If not could I use the Sabertooth Dual 50A motor Driver with the AVR 1.5 that tronic made? I would love to use tronics setup since it is so cheap to make. The dual 50A motor driver would definitely cover the 40amp stall so I don't know what to do. I'm going full steam ahead on this project I just ran into about $300 of expendable cash from selling some old computers and parts so Im gonna stay at this thing but the sabertoothe is $250 !!

Tronic - earlier in one of these threads you indicate that one should use IRLZ44's in place of IRFZ44.
Additionally, on this page (http://www.x-simulator.de/wiki/Dual_Mosfet_H-bridge_by_Tronicgr), you make this recommendation:
You can make the DSMhb1.2b stronger by replacing the IRFZ44 mosfets with IRF3205 mosfets that deliver more ampere and match better the ampere rate of the IRF4905.

Given that, if I need to really go with the IRLZ44's, is there a high ampere mosfet that I should be using in place of the IRLZ44?

BTW - I've forgone wiper motors. Instead, I've altered some hand-crank cable wenches that use worm-gears, so that I can really apply some torque. The wench rating is 1000 lbs and the hardware is very stout. I can connect pretty much any motor to it and get the rotation/torque I need.

Thanks.

Well, if you look the datasheets...

the IRF3205 has VGS 10V

and

the IRLZ44 has VGS = 5.0 V

Go ahead and try first the IRLZ44 that is Logic Part and turns fully on by the 5V that 74HC08 provides. In fact I used without problem the IRF3205 without problems even if the gate doesnt turn on fully given that it needs 10v, in my last h-brigde, because the IRF3205 is more heat tolerant and I always use good cooler with fan on them.