Custom H-Bridge (tha MOSFET mod)
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ph2t
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CaboWabo
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that rocks dude.ok, I'm either sending off my PCB or I'm gonna do this mutha myself.
Dear Life Cereal, Where do you get off? Part of a balanced breakfast and delicious? Who do you think you are? By now you may have guessed I'm speaking ironically and have nothing but good things to say about what you do. Life cereal do not change a thing.
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ph2t
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Your call Cab's 
. I'm still getting all my changes down pat. What you see is a lot of stuffing around and lots of wire coming out of the pcb, you'd hate it. I've got some parts on order, which should be able to prove to me weather I can leave the transistors in the circuit.
I'ts 1:22am here so I'm gonna crash.
ph2t.
. I'm still getting all my changes down pat. What you see is a lot of stuffing around and lots of wire coming out of the pcb, you'd hate it. I've got some parts on order, which should be able to prove to me weather I can leave the transistors in the circuit.I'ts 1:22am here so I'm gonna crash.
ph2t.
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ph2t
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ph2t
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I was talking to MicroAmps the other day and he was telling me how the newer perfection motors 4.0 & 4.2 have the tendency to "keep going" after leftting go of the fwd button. These motors have bugger all inertia on the rotor so they don't apply any breaking abilty unlike the lower rated motors, 1.0, 2.0, 2.2,...
The most excellent Japanese Bitchar-G website ex.2 BirChar-G has a mod for the H-bridge which gives to motor the ability to act like a brake. So when you didn't press either fwd or rev the motor was acting as a brake.
It's called the Neutral-brake Custom.
The circuit has some extra components added to the regular transistor H-bridge.
It also needs to be modded even futher to be able to use FETs, still researching that one.
Breaking though hey? hmm,.... What sort of affect will that have on driving? Very interesting.
The most excellent Japanese Bitchar-G website ex.2 BirChar-G has a mod for the H-bridge which gives to motor the ability to act like a brake. So when you didn't press either fwd or rev the motor was acting as a brake.
It's called the Neutral-brake Custom.
The circuit has some extra components added to the regular transistor H-bridge.
It also needs to be modded even futher to be able to use FETs, still researching that one.
Breaking though hey? hmm,.... What sort of affect will that have on driving? Very interesting.
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micro_Amps
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Hey ph2t, I just took a second look at that neutral brake circuit you posted. That circuit isnt going to work. The resistors from the PNP transistors need to cross the h-bridge to get potential accross the motor.
The PNPs cant be switched like that anyway.
Maybe its a typo from the most honourable site, but velly solly, I dont tink it'll work.
The only main difference is the 2 diodes shorting out the armature. I think this could be improved upon.
What do you reckon?
uA
The PNPs cant be switched like that anyway.
Maybe its a typo from the most honourable site, but velly solly, I dont tink it'll work.
The only main difference is the 2 diodes shorting out the armature. I think this could be improved upon.
What do you reckon?
uAmicro fet mod, BCG, ZZ, website => MicroAmps homepage website
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ph2t
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I agree with your sentiments micro, I believe that the break model does have issues. I been doing research on the whole H-bridge design and found that they can differ wildly. A lot of designs have a shitload of components which is a luxury we don't have given space is a premium.
Once some more parts from onsemi.com arrive I'll have the chance to check it out and get a brake prototype going. For one thing you don't want a hell of alot of current going through the motor, this will just drain the batteries to much whilst the car is at a standstill.
Once some more parts from onsemi.com arrive I'll have the chance to check it out and get a brake prototype going. For one thing you don't want a hell of alot of current going through the motor, this will just drain the batteries to much whilst the car is at a standstill.
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ph2t
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The second prototype.
Well I've advanced some more from the first design and I now have the FET h-bridge and the 5V DC converter on the same PCB. This now gives me enough space to be able to put a shell on the car.
On the left is the 5V DC converter and on the right is the H-bridge. I use the 5V source to be able to turn on the FETs as much as possible to get the ultra low Rds of 0.023 Ohms. Without the 5V source the FETs weren't turned on a much and this meant the motor was getting stuff all current. IE: a fricken slow car
.
I still haven't fixed the problem with having to remove the original transistors so the LXX clone I'm working on has these transistors removed. So to be able to get the FETs a 5V turn on voltage I have to supply the RX chip with 5V. To do this I need to remove the 3V DCDC converter on the board and substitute the 5V one.
In the picture below you can see a little black rectangle part, this is the 3V converter. Also next to it is the 220uH inductor ( the green resistor looking thing with stripes on it).
Also on the underside of the PCB is a diode that needs to be removed as well. (The red cylinder at the bottom middle of the pcb)
The following two pictures show them removed.
3V DCDC Converter & Inductor
Diode
As is the problem with SMD parts. Some of the can die in the process. Like our little friend the 3V DCDC converter who lost a leg, ouch!
So after lots of soldering and wire connecting I managed to get BEAST-2(tm) together.
A true sleeper.......
As I stated earlier, all the stuffing around with the 3V DCDC converter and extra soldering and removing the original transistors will not be part of the final design, this is just me stuffing around and and being a freak, lol!. I'm waiting on some parts to be able to do the "leave the transistors in" mod. Once that happens, well.........
ph2t.[/img]
On the left is the 5V DC converter and on the right is the H-bridge. I use the 5V source to be able to turn on the FETs as much as possible to get the ultra low Rds of 0.023 Ohms. Without the 5V source the FETs weren't turned on a much and this meant the motor was getting stuff all current. IE: a fricken slow car
.I still haven't fixed the problem with having to remove the original transistors so the LXX clone I'm working on has these transistors removed. So to be able to get the FETs a 5V turn on voltage I have to supply the RX chip with 5V. To do this I need to remove the 3V DCDC converter on the board and substitute the 5V one.
In the picture below you can see a little black rectangle part, this is the 3V converter. Also next to it is the 220uH inductor ( the green resistor looking thing with stripes on it).
Also on the underside of the PCB is a diode that needs to be removed as well. (The red cylinder at the bottom middle of the pcb)
The following two pictures show them removed.
3V DCDC Converter & Inductor
Diode
As is the problem with SMD parts. Some of the can die in the process. Like our little friend the 3V DCDC converter who lost a leg, ouch!
So after lots of soldering and wire connecting I managed to get BEAST-2(tm) together.
A true sleeper.......
As I stated earlier, all the stuffing around with the 3V DCDC converter and extra soldering and removing the original transistors will not be part of the final design, this is just me stuffing around and and being a freak, lol!. I'm waiting on some parts to be able to do the "leave the transistors in" mod. Once that happens, well.........
ph2t.[/img]
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cowfish_29
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ph2t
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There would be 4 points on the car's pcb you would solder. One for power, one for Ground. Then one for fwd and one for reverse. The motor wires would be removed from the RX pcb and re-soldered to the FET pcb.
Again, the goal to not remove and components on the pcb, making this a really easy mod in the end, hopefully!
ph2t.
Again, the goal to not remove and components on the pcb, making this a really easy mod in the end, hopefully!
ph2t.
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ph2t
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OK, I *think* I've got it now...... I've managed to put the whole design together and come up with this....
The two 2N2222 transistors will connect to the bit PCB and take the fwd/reverse signals and supply them to the FETS. This way YOU DON'T HAVE TO MOD THE BIT PCB AT ALL, YEAH!
I will put this design together over the next few days and let you pimps know if I'm successful or not. Once I've mastered this I will then work on the neutral brake circuit I posted earlier in this thread. I know the above circuit is just a pretty picture for most of you but I'm hoping that this will inspire any other dormant techos out there to get in on tha action......
I've found another FET as well that is pretty much the same spec and SO-8 package as the other FETs I've used (as shown in the pics posted), but there are two FETs in this single package which will save a shitload of space.....
More to come.......
The two 2N2222 transistors will connect to the bit PCB and take the fwd/reverse signals and supply them to the FETS. This way YOU DON'T HAVE TO MOD THE BIT PCB AT ALL, YEAH!
I will put this design together over the next few days and let you pimps know if I'm successful or not. Once I've mastered this I will then work on the neutral brake circuit I posted earlier in this thread. I know the above circuit is just a pretty picture for most of you but I'm hoping that this will inspire any other dormant techos out there to get in on tha action......
I've found another FET as well that is pretty much the same spec and SO-8 package as the other FETs I've used (as shown in the pics posted), but there are two FETs in this single package which will save a shitload of space.....
More to come.......
