ph2t
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Nah man, they only have one FET in each. The pins on the SO-8 package double/quad up for current flow.
See there is only one Gate pin.
Micro, when you measured the output voltage from the RX chip on these clones was that as an open circuit? If the measurment was taken in circuit you might find that it is 0.7 volts because that’s the potential of the P-N junction from Base to Emitter of the NPN transistor. The Lxx clone I had had no problems. I measured the output voltage as an open circuit at 1.3V.
ph2t.
Nah man, they only have one FET in each. The pins on the SO-8 package double/quad up for current flow.
See there is only one Gate pin.
Micro, when you measured the output voltage from the RX chip on these clones was that as an open circuit? If the measurment was taken in circuit you might find that it is 0.7 volts because that’s the potential of the P-N junction from Base to Emitter of the NPN transistor. The Lxx clone I had had no problems. I measured the output voltage as an open circuit at 1.3V.
ph2t.
I wanted to find a FET that had an even lower Rds value than the FET made popular by this mod. The IRLML2502 has a typical value of 0.045 Ohms. I found this FET NTMS7N03R2 with a typical value of 0.023 Ohms. Half the Rds of the normal FET used!!! Cool! (In a very sad freakazoid sorta way…).
The package these NTMS7N03R2 is different to the ones normally used. So different in fact I’m gonna have to make a new PCB for ’em.
The FET is that little black package, I put a steering knuckle next to it to give you guys an idea of its size. On the right is the prototype track layout for the PCB.
Cause I don’t have the tools I’m gonna have to draw the track work onto the virgin copper PCB using a special reistive pen.
Now I let it dry for a few minutes then I put the PCB in some etching solution (basically an acid). After about 7 minutes all the uncovered copper is eaten away and I’m left with this:
Now to solder those FETs on.
Putting the FET board on the car
Now that the FET PCB is ready I need to connect it to the car. The car I’ve chosen to mod is an Lxx booster, the auto modellista one. First I’ve ripped the old transistors out and circled the area where I need to connect the FETs to in yellow.
After connecting the steering wires to the transistor pads circled above I then connected the FET PCB to the power terminals on the car PCB and then I removed the wires to the motor from the car and attached them to the FET PCB.
So the power wires go to the FET board, the steering wires (from the transistor pads, not the actual fine steering wires!) go to the FET PCB, BUT the motor is wired straight to the FET PCB.
That’s it. The only bugger is making the custom PCB, but I guess I could get the parts to do this fabrication using the PC instead of hand drawing it…..
I will post video of my testing ’cause I want to see how my own version of ths mod performs against the original German one. Just quickly I put the Lxx car on a cushion on my couch which is on an angle of about 50-60 degress. In un-boosted mode the car stood still and didn’t roll back. In boosted mode the @#$%^ acutally climbed the bloody cushion. More tests to follow.
ph2t.
Edited by – ph2t on 14 June 2003 10:49:09
I wanted to find a FET that had an even lower Rds value than the FET made popular by this mod. The IRLML2502 has a typical value of 0.045 Ohms. I found this FET NTMS7N03R2 with a typical value of 0.023 Ohms. Half the Rds of the normal FET used!!! Cool! (In a very sad freakazoid sorta way…).
The package these NTMS7N03R2 is different to the ones normally used. So different in fact I’m gonna have to make a new PCB for ’em.
The FET is that little black package, I put a steering knuckle next to it to give you guys an idea of its size. On the right is the prototype track layout for the PCB.
Cause I don’t have the tools I’m gonna have to draw the track work onto the virgin copper PCB using a special reistive pen.
Now I let it dry for a few minutes then I put the PCB in some etching solution (basically an acid). After about 7 minutes all the uncovered copper is eaten away and I’m left with this:
Now to solder those FETs on.
Putting the FET board on the car
Now that the FET PCB is ready I need to connect it to the car. The car I’ve chosen to mod is an Lxx booster, the auto modellista one. First I’ve ripped the old transistors out and circled the area where I need to connect the FETs to in yellow.
After connecting the steering wires to the transistor pads circled above I then connected the FET PCB to the power terminals on the car PCB and then I removed the wires to the motor from the car and attached them to the FET PCB.
So the power wires go to the FET board, the steering wires (from the transistor pads, not the actual fine steering wires!) go to the FET PCB, BUT the motor is wired straight to the FET PCB.
That’s it. The only bugger is making the custom PCB, but I guess I could get the parts to do this fabrication using the PC instead of hand drawing it…..
I will post video of my testing ’cause I want to see how my own version of ths mod performs against the original German one. Just quickly I put the Lxx car on a cushion on my couch which is on an angle of about 50-60 degress. In un-boosted mode the car stood still and didn’t roll back. In boosted mode the @#$%^ acutally climbed the bloody cushion. More tests to follow.
ph2t.
Edited by – ph2t on 14 June 2003 10:49:09
