General Category > eBike Mods/Legalization
Cycle Analyst diagram for Magic Pie. Speed and current control.
GM Canada:
Hi Paul
What a wonderful style of writing you have. Everything is easily understood and I had a few laughs along the way. Thank you for that!
Gary
Leslie:
The th pad is a current sink and nothing more. If it was voltage based as in resistive energy control by reference voltage controll we wouldnt have to play around like we do with R6 and diodes and what not..
Its prurely based on the current that comes from your throttle and is required by your controller. The volt settings are a hit miss thing very losely implemeted on basic charasteristics most controllers throttle interface exhibit.
The rest is getting your hands dirty and actually measuring the current that goes to your controller when you twist the throttle and sinking the correct ratio of current to the th and controller to achieved the voltage set by interm.
Its not rocket science and to s small degree, nothing to do with how much you know about electronics. Even an expert would have problems following that write up as it does not define exactly what part and piece they are talking about. Even an expert would to fill in the gaps to have i9t make sense.
I think it more like its written by someone who knows what bits theyre thinking of in their own head.
Other than that I suspect the diode and resistor do not belong there and looking closer at the mod it is not correct.. You may get it to work but the TH pad would be lucky to get 2.83v to sink not 4v as the manual states..
Leslie:
--- Quote ---In most setups, the user typically has a throttle signal that varies from close to 0 or 1V when it is off, up to 4-5 V when the throttle is fully engaged. For proper operation of the Cycle Analyst limitting features, the signal for the motor controller should be the lower of these two voltages. An easy way to achieve this without even opening the controller is with a diode and current limiting resistor on the throttle line as shown in the following schematic:
--- End quote ---
In laymen terms to read this means one does not need the diode and or resistor if you have the lower of these two voltages. One need the diode and resistor to achieve 4v to the th pad. As we all know the MC outputs lower than 4v. And the voltage from the resistor and diode would take the voltage down below I repeat below 3v.
Either the web site is wrong or poorly written or you guys are right. Either way the Mod here contradicts what is written on the Web site when it concerns the magic controller.
--- Quote ---Jumper R6 on the circuitboard of the cycle analyst stops a lot of voltage going back into the cycle analyst, but the Magic pie produces more than the resistor can handle, and this means that the resistor needs to be "bypassed" in order to let the current through....in my case a metal pin soldered to both ends, now looking like a u shape.....
--- End quote ---
Like reducing ohms in a circuit adds more protection to the "op amp" that the R6 resistor protects? The resistor is there to protect the op amp from higher voltages. And reducing this resistor only puts the op amp in danger not "the MP produces too much for the resistor" (you mean op amp) yep, so we need to put the op amp in more harms way, is exactly what you are saying in this quote. Not!
Justin means exackerly this.
If someone hooks an undermined power source to the th pad it will fry the op amp protected by R6. If the current demand is too low from the controller off the throttle, the th pad R6 resistor needs to be shorted to lower the resistance for sinking more current off the throttle to the TH pad to make the throttle limiter effective. The hall sensor is literally loaded higher in limit mode and current paths are split to the controller and to the th pad. This creates a voltage drop straight over the hall sensor and 330 ohm resistor. where there is a voltage drop you have a current impedance. in turn the current that is shunted to the th pad limits the current going to the controller. So in essence it not voltage based its current based.
I can feed a control throttle signal to a controller 10v @.005ma and the bike it would not move a single inch. Or I could feed the controller 4v @ 100 amps and the controller would still only draw 5ma or so from the throttle.
Its not all cut and dry.
As far as the th pad sending volts out to the controller past the .8v that the throttle gnd should slam down, with out a 330 ohm resistor the th pad volts should be slapped down easily by the hall sensors path to ground @ 0 twist..
So omitting both resistor and diode in the mod diagram should have any current from the th pad sink into the gnd at the hall sensor no problems.
So diode needing to block th op amp transients or non load voltage tails I have no clue what you talking about. Unless you were to hook up the CA to the controller first with no throttle connected. You could have problems then.
As it states you need the diode and resistor for voltages @ 5v so the CA does not sink too much current from the throttle.
But hey I could be wrong. I just switch my CA on and it went up in smoke and I had to switch it off to avoid a fire.. Installed and untouched since.
DirtyGinge:
Hi :)
Yes I agree there is a lot more to it, and yep, shorting R6 to allow currents back into the op-amp is certainly a massive risk, especially if someone wires it wrong......
However, as this was the reason that I purchased the CA, to make the motor"legal", I had to try, and the guides written out there are somewhat cumbersome......I didnt find any basic information from anyone apart from gary on the mod that works with the Magic Pie, tried the other method, didnt like it :(
The average person on the street will have no idea what a voltage sink is ( toaster in the wash basin ?) or the concept of what its trying to do, so I wrote my guide to try and help them more understand the concept, then the other forum posts would begin to make sense...
I agree also that the Th pad will not sink the 4V, more like 2.5, but this is perfect in limiting the speed, expecially once my fat A$% is on the saddle.....
Shame the manufacturers cant make it a little easier for the newb
Leslie:
--- Quote from: dirtyGinge on November 22, 2010, 06:44:14 AM ---Hi :)
Yes I agree there is a lot more to it, and yep, shorting R6 to allow currents back into the op-amp is certainly a massive risk, especially if someone wires it wrong......
However, as this was the reason that I purchased the CA, to make the motor"legal", I had to try, and the guides written out there are somewhat cumbersome......I didnt find any basic information from anyone apart from gary on the mod that works with the Magic Pie, tried the other method, didnt like it :(
The average person on the street will have no idea what a voltage sink is ( toaster in the wash basin ?) or the concept of what its trying to do, so I wrote my guide to try and help them more understand the concept, then the other forum posts would begin to make sense...
I agree also that the Th pad will not sink the 4V, more like 2.5, but this is perfect in limiting the speed, expecially once my fat A$% is on the saddle.....
Shame the manufacturers cant make it a little easier for the newb
--- End quote ---
Agreed,
It would help a little if the power from and to the said devices were refereed to in every instance in the write up.
Its very hard to communicate such information when the author knows the circuit well and has to communicate on a lower level or even to a person who is a little more tuned to the jargon may still get confused if details around the circuit are a little lose..
Reading it a few times helps and the dots start to join.
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