Cheers, Pewe
I am looking for a 12 V DC motor than can zoom up to about 3,000 rpm - it is to drive a car speedo. It will be driven from low rpm so has to be
respond well to low voltage (or do I pulse it?)
Not found anything suitable yeat (maplin/ebay/rs) - anyone know of one? (will look round model shops).
12 v dc rechargeable drill motor?
Dead cheap s/hand as the drills are crap!
Some people always want the obscure don't they? ... try www.parvalux.co.uk if they can't help they will probably know somene who can.
Cheers, Pewe
Sounds like you need a stepper motor.
Either that or one out of a scalextric car!
Either way I can help. U2U me if I can help.
Ive also considered trying to build something like this to allow an electrical drive of a mechanical speedo.
I found some usable motors in my box of old printer and disk drive parts, the tray motor on a CD drive looks usable.i think it may need a feedback
system adding either a magnetic or optical encoder would do .There is a motor on the distel site that looks as if it may work and includes an encoder
but is a bit on the large side.
Most ford speedos are 1000 tpm so 1000rpm would be 60mph and therefore 3000 is more than adequate for a seven type application.
My idea is to use an analog system to give a voltage using a comparator type circuit and using the input pulses to give a variable input voltage.
Paul.
Would it not be far easier to just drve a stepper from a proper chip that runs off the pulse input?? Replace thew speedo guts with the stepper.
Or feed the pulses into a PIC, and output to a digi readout??
Far less complicated.
Cheers,
Syd 
That may be an easier solution , but my intention was to make an add on unit that people could use to modify any mechanical speedo to fit a different
engine gearbox combination . It would consist of a small servo motor that could be attached in place of the original cable and a sender and control
calibration box for the gearbox or propshaft, and would make it much easier to use different donor instruments.
Paul.
quote:
Originally posted by Syd Bridge
Would it not be far easier to just drve a stepper from a proper chip that runs off the pulse input?? Replace thew speedo guts with the stepper.
Or feed the pulses into a PIC, and output to a digi readout??
Far less complicated.
Cheers,
Syd
most model shops can provide 12v dc motors in either brushed, or preferably brushless configuration...
One sorce of small brushless motors is also CD-Rom drives that you no longer use...
got a motor from maplins; not man enough to turn the speedo 
, so £ 5 badly spent.
Also got a stepper - boy do they have some torque
not sure it can go at those sort of speeds I need (my calculation is somewhere between 2 and 3 000 rpm; it is not a Ford speedo). maybe I can drive
it that fast or else may need a couple of gears.
all the bits of money spent makes me wonder whether to splash out on a new one ... but will look on ebay onece in a while.
quote:
Originally posted by Syd Bridge
Would it not be far easier to just drve a stepper from a proper chip that runs off the pulse input?? Replace thew speedo guts with the stepper.
Or feed the pulses into a PIC, and output to a digi readout??