The DC Mod
Posted: Mon Jul 18, 2005 2:28 pm
What it is
The DC Mod is brought to us by Codesuidae. You can read all about it at his website, http://codesuidae.net/ , but I'm gonna try to summarize here.
First thing we need to know in order to understand this mod, is that the Zip Zap SE pulses the current to the motor. The number of times that the motor pulses within a specified time is the Duty Cycle. Even at full throttle SEs are still pulsing the throttle, and limiting power to the motor. The earlier ones ran at an atrocious 30% Duty Cycle, which meant the motor is actually off 70% of the time. The most recent versions of the SE have a greatly improved 55% Duty Cycle, which with the SE's 2.4v power source puts it about on track with an OG Zip Zap, which is good thing, but there's lots of room for improvement, and that's where the DC Mods steps in.
The DC Mod is a chip that intercepts the signal from the "black blob" and converts the Duty Cycle to 100% at full throttle. Effectively delivering the full 2.4v from the battery and making it perform very much like a dual cell car
The car with the mod istalled. Notice its conveniently out of the way on top of the motor.
Installation
The DC Mod is a fairly simple operation, if you've had experience working on these tiny PCBs. It involves the removal of one resistor, and the hook up of 4 wires.
Code includes installation instructions on his website, and I opted to install it myself, but Code does offer an installation service for a very reasonable fee. If you’re at all uncomfortable performing this mod your car, this may be the way to go. I have personally had a lot of bad experiences with SEs mysteriously dying, and this one was no exception. I am baffled how I managed to short something out the first time I installed it, but that just goes to show that if even if your confident with your skills, there is a always a certain level of risk involved if you're not careful.
After reviving my car I was able to get it working the second time. While the car worked, the mod didn't seem to function at first, but Code informed me that later model SEs require pins 3 and 4 jumpered and that solved the problem.
I made up this basic installation diagram, for those of us that benefit from basic diagrams.
NOTE: This diagram is for a FET modded car. A car without FETs requires a resistor.I need to find out where so I can update my diagram.
Performance
Once I got it working and I pulled the throttle, I immediately heard that familiar whine of a motor being pushed by 2.4 volts, and I knew it was good. On the ground the car performed very much like an old school dual cell Zip Zap, except it is a heavier car, so it throws its weight around quite bit more. The 5 step throttle being spread out over the greater range of speed kind of limits the amount of control you have, but still gives you quite bit more control than single speed RC.
It seems to help with steering jitters at full speed. Code says this is an unintentional side effect, and doesn't happen with all cars. I think because I installed this in a GTO chassis, with the steering nearly fixed to begin with, that helped out quite a bit.
While the car is smooth at full throttle you can still hear the motor buzz at the slowest speeds. This doesn’t really bother me, but I thought it worth noting.
Overall it is a bit of a squirrelly ride, but what a blast it is.
Check out the video I made to get an idea of how the Duty Cycle effects the performance of the car.
SE Shootout
3:30 minute
7MB WMV
(**Note: This video is not meant to be an end all comparison. The faster cars were handicapped inthe smaller running area, and are both new to me. The video does however show an improvement from car to car, and that's all that is intended.)
Bottom Line
When the news of the Zip Zap SE hit, lots of people got excited, "Could it be true, a fully proportional, reasonably priced, 1/64th scale RC?", and I think in many peoples eyes, Radio Shack clearly dropped the ball. Left us all disappointed, and scrambling for a better option.
Those of you that have already gone the route of installing an Iwaver PCB in your SE, may not have much to get excited about. I would have to guess that you'd feel limited having 1/100th of the steps in control that you're used to, but for the rest of us that were looking for an inexpensive easy way to unlock the potential of the SE, I believe we now have our answer.
This mod makes the SE a truly fun car, despite the inherent drawbacks of the SE, but that is not to say Code is done yet. Code mentioned to me future projects involving upping the PWM (Pulse wave Modulation) to something faster than 100hz, to help with the buzzing. He also mentioned converting some of the reverse steps to forwards, giving 9 steps forwards and one reverse. That is something I'd really like to see, but it does add some difficulty to the mod.
I'd like to commend Code for the work he's done, and for doing it at a reasonable price point. I can't wait to see what he comes up with next.
The DC Mod is brought to us by Codesuidae. You can read all about it at his website, http://codesuidae.net/ , but I'm gonna try to summarize here.
First thing we need to know in order to understand this mod, is that the Zip Zap SE pulses the current to the motor. The number of times that the motor pulses within a specified time is the Duty Cycle. Even at full throttle SEs are still pulsing the throttle, and limiting power to the motor. The earlier ones ran at an atrocious 30% Duty Cycle, which meant the motor is actually off 70% of the time. The most recent versions of the SE have a greatly improved 55% Duty Cycle, which with the SE's 2.4v power source puts it about on track with an OG Zip Zap, which is good thing, but there's lots of room for improvement, and that's where the DC Mods steps in.
The DC Mod is a chip that intercepts the signal from the "black blob" and converts the Duty Cycle to 100% at full throttle. Effectively delivering the full 2.4v from the battery and making it perform very much like a dual cell car
The car with the mod istalled. Notice its conveniently out of the way on top of the motor.
Installation
The DC Mod is a fairly simple operation, if you've had experience working on these tiny PCBs. It involves the removal of one resistor, and the hook up of 4 wires.
Code includes installation instructions on his website, and I opted to install it myself, but Code does offer an installation service for a very reasonable fee. If you’re at all uncomfortable performing this mod your car, this may be the way to go. I have personally had a lot of bad experiences with SEs mysteriously dying, and this one was no exception. I am baffled how I managed to short something out the first time I installed it, but that just goes to show that if even if your confident with your skills, there is a always a certain level of risk involved if you're not careful.
After reviving my car I was able to get it working the second time. While the car worked, the mod didn't seem to function at first, but Code informed me that later model SEs require pins 3 and 4 jumpered and that solved the problem.
I made up this basic installation diagram, for those of us that benefit from basic diagrams.
NOTE: This diagram is for a FET modded car. A car without FETs requires a resistor.I need to find out where so I can update my diagram.
Performance
Once I got it working and I pulled the throttle, I immediately heard that familiar whine of a motor being pushed by 2.4 volts, and I knew it was good. On the ground the car performed very much like an old school dual cell Zip Zap, except it is a heavier car, so it throws its weight around quite bit more. The 5 step throttle being spread out over the greater range of speed kind of limits the amount of control you have, but still gives you quite bit more control than single speed RC.
It seems to help with steering jitters at full speed. Code says this is an unintentional side effect, and doesn't happen with all cars. I think because I installed this in a GTO chassis, with the steering nearly fixed to begin with, that helped out quite a bit.
While the car is smooth at full throttle you can still hear the motor buzz at the slowest speeds. This doesn’t really bother me, but I thought it worth noting.
Overall it is a bit of a squirrelly ride, but what a blast it is.
Check out the video I made to get an idea of how the Duty Cycle effects the performance of the car.
SE Shootout
3:30 minute
7MB WMV
(**Note: This video is not meant to be an end all comparison. The faster cars were handicapped inthe smaller running area, and are both new to me. The video does however show an improvement from car to car, and that's all that is intended.)
Bottom Line
When the news of the Zip Zap SE hit, lots of people got excited, "Could it be true, a fully proportional, reasonably priced, 1/64th scale RC?", and I think in many peoples eyes, Radio Shack clearly dropped the ball. Left us all disappointed, and scrambling for a better option.
Those of you that have already gone the route of installing an Iwaver PCB in your SE, may not have much to get excited about. I would have to guess that you'd feel limited having 1/100th of the steps in control that you're used to, but for the rest of us that were looking for an inexpensive easy way to unlock the potential of the SE, I believe we now have our answer.
This mod makes the SE a truly fun car, despite the inherent drawbacks of the SE, but that is not to say Code is done yet. Code mentioned to me future projects involving upping the PWM (Pulse wave Modulation) to something faster than 100hz, to help with the buzzing. He also mentioned converting some of the reverse steps to forwards, giving 9 steps forwards and one reverse. That is something I'd really like to see, but it does add some difficulty to the mod.
I'd like to commend Code for the work he's done, and for doing it at a reasonable price point. I can't wait to see what he comes up with next.
)
