Speedo out to drive DC motor
Speedo out to drive DC motor
I have added a small DC motor to drive the mechanical speedo on one of my cars but that incoportated a lot of work with the electronics...
It should be bossible to drive a small low rpm dc motor directly from the speedo output by removing the pull-up resistor and adding the fly-back diod?
The DC motor I'm looking at will only use 200mA
BR//Tobmag
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Re: Speedo out to drive DC motor
Re: Speedo out to drive DC motor
But I could use SP1 or 2 in PWM mode using speed as index value?
BR//Tobmag
Re: Speedo out to drive DC motor
Running SP1 in PWM mode.
The only thing is that it seems to be a hick-up in the code since the PWM signals and motor stops at every gearchange, up and down shifting.
BR//Tobmag
Re: Speedo out to drive DC motor
Would you be willing to disclose what motor and electronics you found to work? I never could figure a way to find the actual power needed to run the cable up to 1500 - 2000 RPM. Is it like 1/10 HP or something?
The only thing I ever knew was that a GM standard was in place that the speedo cable RPM was supposed to be 1000 at 60MPH.
Is that motor something a guy could buy on ebay or some other low cost vendor?
Re: Speedo out to drive DC motor
eBay link deleted per forum rules
Re: Speedo out to drive DC motor
There is no need for any additional PWM control. You can use either SP1 or SP2 directly since they are capable of putting out a PWM signal, the driver can handle up to 7,5A if I dont remeber wrong.
Right now I use an old motor from a scrapped VCR player. Problem is that its not spinning fast enough just reaching 110mph and is not putting out high tourqe enough at lower speed so it will jump start to 20mph.
I'll pass by the local R/C shop and see what they have in terms of electric motors for R/C controlled cars etc. They should have something suiteble and they are usually very powerfull and depending of application spinning fast enough (i hope) thing there is that they are usually 7,2V but that you can controll by limiting the PWM signal.
I'm using the same VCR motor to another car I have and that one is working as a dream, different speedo though...
I hope Lance can explain why the PWM signal is dropping to zero when changing gears.
BR//Tobmag
Re: Speedo out to drive DC motor
have you seen any evidence of Lance or forum admins logged on here recently? kinda looks like the activity has really died off here.
Re: Speedo out to drive DC motor
It makes you think if the GPIO board was the way to go for the tranny control, yes cheap but what does that help you if there is no or very limited support?
The concept is brilliant when you can connect it over the CAN to the engine management and very few manufactures out there today that can offer this.
But as with all these DIY things in the end it all comes down to the support......
BR//Tobmag
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Re: Speedo out to drive DC motor
The PWM isn't supposed to drop to zero when changing gears (unless you tell it too using "Shift Line Pressure Settings": http://www.msgpio.com/manuals/mshift/V22tune.html#gl). So make sure you have those set appropriately.
I have been traveling the last week (to PRI to meet with Bruce and Al on various topics) but in general, I am slow to respond to post if:
- it doesn't not state the code version and include an MSQ and a datalog of the problem,
- it covers an issue already documented (http://www.msgpio.com/manuals/mshift/V22tune.html),
- it asks for information that I don't know (such as about a transmission that is new and unfamiliar to me),
- it asks about using the MShift in novel ways that the code was never intended to be used (in which case I will help if I can, but the user has to have explored all the current code parameters, and the come up with a proposed solution that I can implement in the code/hardware).
Tobmag, the current code is 100% documented. If I get run over by a bus, when the cheering stops users will have access to complete descriptions of all the parameters available on the web and in TunerStudio. This is entirely unlike some efforts, where the documentation lags months or years behind code releases.
Lance.