More MOSFET moddin stuff
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micro_Amps
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More MOSFET moddin stuff
I see you guys are talking mosfets so I thought I'd put my 2 cents worth in as well.
Heres a pic of a single speed BCG that has been fet modded. This one is based on the German mod where 2 fets sit on the underneith of the pcb. This is an old pic, I've changed the mod now and put all 4 N channel fets on the top of the pcb. Looks better, cools better, and leaves the opportunity for stacking another set of fets on top of the first set to further reduce bridge resistance and increase motor current.
(Sorry about the big pic.)
A standard single cell booster with a 3.5 motor and orange gears goes at about 2.1 / 3.4 mph (unboost / boosted)
After fet modding the motor bridge the same car goes 3.7 / 5.2 mph
(unboost/boosted) It goes better unboosted after the fet mod than it did boosted before the mod. On boost it pops wheelies and screams accross carpet like its on floor boards. And the torque is increased massively too. After the mod, the only limitation to climbing inclines is traction, 45 degrees + is possible. To take things to insane levels, I have a tricell booster fet modded car that runs a 4.0 motor, bit racer gears and maxs out at 17.8 mph on the speed checker. It takes a while to get up to speed on the floor but it is bizarre to watch a car so tiny go that fast.
Since I have been doing these fet mods, a few people have been asking me to mod their cars, which I have been doing. I can alter the mod to suit Tomy cars, all the clones, zipzaps, hummers, anything. If anybody wants to try one I guess you can email me on bitstuff@dodo.com.au , I'd be happy to help.
For those interested, I will leave more details in the fo' sale section. This is the link
Anyway, enough rambling from me.
uA
Heres a pic of a single speed BCG that has been fet modded. This one is based on the German mod where 2 fets sit on the underneith of the pcb. This is an old pic, I've changed the mod now and put all 4 N channel fets on the top of the pcb. Looks better, cools better, and leaves the opportunity for stacking another set of fets on top of the first set to further reduce bridge resistance and increase motor current.
(Sorry about the big pic.)
A standard single cell booster with a 3.5 motor and orange gears goes at about 2.1 / 3.4 mph (unboost / boosted)
After fet modding the motor bridge the same car goes 3.7 / 5.2 mph
(unboost/boosted) It goes better unboosted after the fet mod than it did boosted before the mod. On boost it pops wheelies and screams accross carpet like its on floor boards. And the torque is increased massively too. After the mod, the only limitation to climbing inclines is traction, 45 degrees + is possible. To take things to insane levels, I have a tricell booster fet modded car that runs a 4.0 motor, bit racer gears and maxs out at 17.8 mph on the speed checker. It takes a while to get up to speed on the floor but it is bizarre to watch a car so tiny go that fast.
Since I have been doing these fet mods, a few people have been asking me to mod their cars, which I have been doing. I can alter the mod to suit Tomy cars, all the clones, zipzaps, hummers, anything. If anybody wants to try one I guess you can email me on bitstuff@dodo.com.au , I'd be happy to help.
For those interested, I will leave more details in the fo' sale section. This is the link
Anyway, enough rambling from me.
uA-
micromatch
- bitGangsta'
- Posts: 367
- Joined: Mon Jul 28, 2003 7:28 pm
- Location: Bay Area califoolyah
yup yup
uh huh it is all true i just got my car from micro amps
back purple tires in the front
red tires in back
soft red suspension with 1 and 1/2 holes
150 mah cell
4.0 motor
this thing flies its so fast... but it flips alot any way to fix this pm me
back purple tires in the front
red tires in back
soft red suspension with 1 and 1/2 holes
150 mah cell
4.0 motor
this thing flies its so fast... but it flips alot any way to fix this pm me
is this thing on?
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micro_Amps
- Posts: 19
- Joined: Wed Apr 30, 2003 6:46 am
- Location: Melbourne, Australia
- Contact:
micromatch, try using harder tires on the front. They slip a little making the turning circle bigger (understeer) but you can take higher speed corners and it wont flip as often.
uA
uAmicro fet mod, BCG, ZZ, website => MicroAmps homepage website
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hogjowlz
- bitPimp
- Posts: 5014
- Joined: Wed Feb 19, 2003 4:05 pm
- Location: uranus
hey microamps
have you fetted a superbit yet? my friend tried to figure it out last night but with the configuration like the german design we only got power in fwd and nothing in reverse. he tried to mess with the pinouts and it only got worse. he knows all that engineering talk stuff and most of the info is geared for the more electronically inclined so he found a lot of it useless.
any help would be great
have you fetted a superbit yet? my friend tried to figure it out last night but with the configuration like the german design we only got power in fwd and nothing in reverse. he tried to mess with the pinouts and it only got worse. he knows all that engineering talk stuff and most of the info is geared for the more electronically inclined so he found a lot of it useless.
any help would be great
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crazydave
- bitPimp
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- Location: Koolsville
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ph2t
- bitPimp
- Posts: 1979
- Joined: Tue Mar 25, 2003 6:33 am
- Location: taco city
The best thing to do is to find that two transistors that are connected to the RX chip. You look for a 0V -> 0.7V change on the BASE pin on two transistors when you press fwd/rev on the controller respectively.
The other two transistors are then found by looking for a voltage that goes to 1.2V (or close) on the motor connection pins. You can usually track the two PNP transistors that way.
ph2t.
The other two transistors are then found by looking for a voltage that goes to 1.2V (or close) on the motor connection pins. You can usually track the two PNP transistors that way.
ph2t.
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crazydave
- bitPimp
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I just look at the markings on the transistors, the PNP are labeled KIY, and a symbol with a thing that looks like an /H, and the NPN is labeled KEY, and a symbol that is like a T in a triangle. On clones the steering transistors should be NPN, so you can use their markings as reference.
Anyways, I've found these are the 2 to flip (poorly marked with faint red arrows)
The problem now is where to put the jumpers. It looks to me like the contact that is going to be left open is going back to the IC under the blob, in both cases. You could just jump the pin back to the open contact, but I'm theorizing a more effecient way.
On the Big Lots cars the PNP, and NPN transistors are reversed, but I believe the PCBs are the same. If I can just swap the NPN, and PNP transistors around, then that would mean I could just flip the opposite 2 , and then bypass the contact with my jumper, making it more efficient. Did that make any sense? Well whether if it did or not, it does to me, I just need to wait for the mosfets to get here, so I can do some experimenting.
Anyways, I've found these are the 2 to flip (poorly marked with faint red arrows)
The problem now is where to put the jumpers. It looks to me like the contact that is going to be left open is going back to the IC under the blob, in both cases. You could just jump the pin back to the open contact, but I'm theorizing a more effecient way.
On the Big Lots cars the PNP, and NPN transistors are reversed, but I believe the PCBs are the same. If I can just swap the NPN, and PNP transistors around, then that would mean I could just flip the opposite 2 , and then bypass the contact with my jumper, making it more efficient. Did that make any sense? Well whether if it did or not, it does to me, I just need to wait for the mosfets to get here, so I can do some experimenting.
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micro_Amps
- Posts: 19
- Joined: Wed Apr 30, 2003 6:46 am
- Location: Melbourne, Australia
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Unfortunately there are other 'issues' on the SBCG pcb as well.
The circuits bare little resemblence to their predecessor, and there are some major hurdles to get over before a SBCG will run as good as a fet modded (first generation) BCG.
I have one on the bench at the moment, but now I'm waiting for parts as the standard mod does not apply. It works but isnt an improvement.
uA
The circuits bare little resemblence to their predecessor, and there are some major hurdles to get over before a SBCG will run as good as a fet modded (first generation) BCG.
I have one on the bench at the moment, but now I'm waiting for parts as the standard mod does not apply. It works but isnt an improvement.
uAmicro fet mod, BCG, ZZ, website => MicroAmps homepage website
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micro_Amps
- Posts: 19
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- Location: Melbourne, Australia
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ph2t, there are huge differences between the old and new BCG's Rx pcb.
Its a generational change, a large departure from the previous circuits.
I am working my way through modding it and dont want to post my results until I get it all sorted out 100%
Let me throw this one at you, as a teaser. You cant dual cell this car, the pcb shuts down on anything over 2.7 volts !!!
But a dual is only 2.4v you say, well when you charge it at 5 or 6 volts the Rx chip shuts down and doesnt recover until the Vcc in disconnected.
This is where your mini DIP switch mod (or more correctly, SIL switch) is going to come in handy to take the cells out of circuit whilst charging
And this is just one of the many things that need to be overcome to get some decent mods performing correctly.
The list of standard Rx pcb mods for the super BCGs will need to be completely re-written, its a different chip folks!!
Goodluck,
uA
Its a generational change, a large departure from the previous circuits.
I am working my way through modding it and dont want to post my results until I get it all sorted out 100%
Let me throw this one at you, as a teaser. You cant dual cell this car, the pcb shuts down on anything over 2.7 volts !!!
But a dual is only 2.4v you say, well when you charge it at 5 or 6 volts the Rx chip shuts down and doesnt recover until the Vcc in disconnected.
This is where your mini DIP switch mod (or more correctly, SIL switch) is going to come in handy to take the cells out of circuit whilst charging
And this is just one of the many things that need to be overcome to get some decent mods performing correctly.
The list of standard Rx pcb mods for the super BCGs will need to be completely re-written, its a different chip folks!!
Goodluck,
uAmicro fet mod, BCG, ZZ, website => MicroAmps homepage website
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crazydave
- bitPimp
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The very interesting micro_amps, thanks for the info.
I had feeling something was up besides the the different layout, because the Super bits handle the 4.2 soooo much better than my Microsizer, the chassis isn't that much lighter, so I had a feeling something is up in the circuit design.
....but I wonder why the mosfets don't give that much improvement, the theory of cutting resistance is the same.
...and I'm baffled that you say they wont run on dual cells, there's been a couple people at TRC that have claimed to dual cell theirs, so were they just blowing smoke up my ass?
I had feeling something was up besides the the different layout, because the Super bits handle the 4.2 soooo much better than my Microsizer, the chassis isn't that much lighter, so I had a feeling something is up in the circuit design.
....but I wonder why the mosfets don't give that much improvement, the theory of cutting resistance is the same.
...and I'm baffled that you say they wont run on dual cells, there's been a couple people at TRC that have claimed to dual cell theirs, so were they just blowing smoke up my ass?
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ph2t
- bitPimp
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possibly, micro is very solid in his work CD, I've had many discussions with him on various electronic issue surrounding these cars.crazydave wrote: ...and I'm baffled that you say they wont run on dual cells, there's been a couple people at TRC that have claimed to dual cell theirs, so were they just blowing smoke up my ass?
ph2t.