Hi. I'm a new member with a PWM add-on enquiry

[Jerry]

Hi.  I'm a new member and I'd like to ask for help in connecting a sound generator module to an MPIII.     The only problem is that the off-the-shelf sound module is designed to look at the PWM waveform that is seen across a motor.   I'm not sure how to hook the sound module signal detection wire up to the MPIII wiring harness to achieve this, but I'm sure that one of the astonishingly knowledgeable members will be able to help.   Could you move this to a suitable thread ?

Thanks

Jerry

[Morgen 3Eman]

Could you show us a wiring diagram or a link to your sound module?

By the way, what is a sound module?  Is that what us old guys called a speaker?

TTFN,
Dennis

[Bikemad]

Hi andto the forum Jerry.

If it can be used with a brushless motor you will probably need to connect it across two of the three phase wires connected on the rear of the controller.

If you have an early MPIII it should be possible to either file a slot or drill a small hole in the controller cover to allow a couple of wires to pass through and connect inside the hub, but you will need to remove it first and  make sure there is nothing in the way that might become damaged by filing or drilling.
You need to make sure that there are no sharp edges that could chaff through the insulation of the wires as this could cause serious problems.

Some of the more recent controllers might be more difficult to access as there is nowhere really suitable to run additional wires through.

By the way, what is a sound module?  Is that what us old guys called a speaker?

Check out this link Dennis and all will be revealed.

Alan
 

[Supchrgamx]

hi tech
we use to do it with a card in the spokes

[Jerry]

Thanks so much for your replies.   I realize now that I didn't explain myself fully.   I want to install a sound module that was originally designed for radio control model kits.   This module will produce realistic engine sounds in direct proportion to the PWM waveform received from a motor.   For weird and twisted reasons, I think it would be highly amusing for this sound module to produce the sound of an old diesel engine in direct proportion to the bikes' speed...     Crazy eh ?    Anyway, I was rather hoping to be able to intercept the motor's PWM waveform through the standard wiring loom, but your comments suggest that this isn't possible.   I don't want to mess about with the controller, so I'll have a think about the cost/complexity of generating a PWM signal using the analog throttle signal.

Thanks   

[Morgen 3Eman]

Hi Jerry,

Actually, there is a way to achieve your goal.  Since you have a pulse width modulated current stream going through the main power conductors, you can make an inductive coupler to sample the frequency and generate a voltage to drive your module. 

In its' simplest form,you can get the signal by simply winding a bunch of turns (That is a technical term, by the way:))  of small gauge insulated wire around one of the pair of main power wires, and connect the ends to the input wires of your module.  I expect your module will have a very high input impedance, so you may not need dozens of turns.  Since the current pulses are quite high amplitude, you may not need many turns at all.  (I'm too lazy to do the math for you)

If I were going to do it, I would try to be as lazy as possible about it.    I'd visit a junk shop and find an old relay, RF choke, or a door bell ringer, or something with a pre wound coil,  strip the winding intact off the center bolt, and poke the main lead through the coil.  If there was room, I'd run two turns?  But I'd try it with just one to see if it will trigger the module. 

You can Google "Inductive coupling" for more information.

TTFN,
Dennis

[Jerry]

Wow.   That is incredibly helpful.   I'll try it !