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Discussion Starter · #1 ·
Has anyone measured the controller output voltage versus the digital speed setting? WIth 15 digital speed settings there will be a range of voltages per digital speed setting...
 

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Yes, I tested and graphed the speed steps at 10%, 50% and 100% settings. I published the findings at the 100% setting only, see post #210 in this thread... It is a comparison of good decoders to faulty ones so just ignore the line that is very different to the others.

From memory, the highest voltage (the 16th step) at 10% setting was about 8V, but I would have to dig up my work from 18 months ago or whenever it was to check. Its on an electronic device someplace, somewhere!
 

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Discussion Starter · #3 ·
I saw your post. Thanks.

I also did something similar when I first got my track.

I am referring to the hand controller not the control unit.

I want to create a table of analog voltage values (ranges) for each of the digital speed values.

I have searched but did find anything yet…
 

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Hmm, interesting, I’ve also wondered a similar thing (but not to the detail you speak of) since there is a 10k fixed value resistor in series with the potentiometer (also 10k)

Could do some basic calculations to estimate it and verify by testing. I don’t have time right now though.
 

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Discussion Starter · #5 ·
Agreed an interesting area to investigate further.

Recording the digital speeds then maybe editing to be played back via the hand controller interface potentially coupled with knowing the car location on the track can make ghosts cars more competitive.
 

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Discussion Starter · #7 ·
Not quite...

With there just being 15 digital speed values, the conversation from the hand controller analog voltage values to a digital value sent to the the car decoder is similar to a 4 bit ADC.

My assumption is that there is a range of hand controller analog voltage values per digital speed value. The digital speed value will change at an analog value when the hand controller speeding up and at another analog voltage value when the hand controller is slowing down. These two values define the analog voltage range for a specific decoder digital speed setting.

This is simply my guess at how things might work without knowing anything about the details oft the hand controller, the analog voltage from the CU and the CU's conversion to a digital speed value for the car decoder.

I was hoping that someone might of gone down this path as could share their knowledge.
 

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Colorfulness Slope Rectangle Font Line


Maybe are you looking for this?
DIfferent "speed" settings, different throttle curve (Volt measured at motor)
(This graph is related to Carrera Original chip)

The throttle curve is made of a 16 step of voltage values, so it's not a real "line".
 

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Nice info there Udo, (and glad I wasn't too far off when I said 8V at speed level 10% at full throttle) but he is talking about the controller potentiometer output to ADC input pin voltage I think, relative to different speed levels.
 

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Ah, sorry, no, I havent measured the controller potentiometer output and yes, a "curve" of those values CAN be different respect to the "Motor Voltage curve output" I shown. (expecially for the X81 chip, which can be set in different ways)

Now I'm curious too.
 

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Discussion Starter · #13 ·
I did some simple measurements of the analog voltages from a standard digital Carrera handset controller to the control unit using a driver's display and a car on the track with some interesting results. For the car on the track I used the motor pitch and current draw from the power supply as indicators of speed. Values are approximate as I didn't go to extremes for accurate measurements at this time. Plans are for a more thorough approach later.

1 - The maximum digital speed is reached well before the maximum possible voltage from the hand controller. ~4.5v (red) is supplied from the control unit to the resistor divider which resulting in a maximum analog voltage of ~2.25v. Maximum digital speed was achieved at ~1.45v (yellow)! Only about 2/3rds of the slider is used...

2 - The driver's display indicator remains the same for 2 speeds values from the hand controller.

3 - For the car I used, the motor started before and speed was indicated on the driver's display.

Rectangle Slope Font Parallel Pattern

Speed StepHand Controller VoltageDriver's Display
1~0.265none
2~0.3651 - red
3~0.421 - red
4~0.512 - red
5~0.592 - red
6~0.683 - green
7~0.753 - green
8~0.844 - green
9~0.934 - green
10~0.985 - green
11~1.075 - green
12~1.146 - green
13~1.226 - green
14~1.37 - green
15~1.427 - green


The measurements where done with a digital scope using statistical measurements reset for each step. There is a bit on noise on the supply voltage which effects the values especially at the lower voltage levels.
 
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