Please identify this motor!

This is my first of hopefully many posts! Although in the future hopefully my questions will be a bit more intriguing lol.

Can anyone identify this motor, what type is it? Is it a stepper? It only has 3to terminals. It is tachometer motor from a 1992 honda prelude gauge cluster I've had in my garage for some time and id like to play around with it and learn how ot control it directly if possible but I need to know what kind it is!



Tried goggling part numbers on the ic's from the control board with nothing found. Not even anything close.

from the pictures it is very difficult to identify this motor, however as you have said that it is a Tachometer motor...........which means its purpose is to generate some certain voltages on some certain revolutions. try to give it some revolutions and than measure voltages around its terminals, it will be DC voltage.

The purpose of these tachometers are to measure revolutions of any revolving thing by means of analog voltage form.

It will not consume voltages as its a tachometer.

Since it has only three terminals ,
positive , ground, control
i think it's a DC Servo motor

Generally Stepper Motors have at Least
4 Terminal -Bipolar Drive
5 Terminal-Unipolar Drive

It rather looks like a kind of moving-magnet or moving-iron instrument driving the tachometer hand.

I think it it is some phase locked motor - locked to wheel speed, driving a conventional eddy current coupling (in the drum below it) that moves the tacho needle. So it could be a 3 phase AC motor or switched DC.?
Frank

Standard BLDC. Does control board contain 3 hall sensors?

I don't clearly see that a regular tachometer is involved with the apparatus. If so, "phase locked" motor (elecitrical shaft) may be an explanation.

sorry, i was on my phone when i posted that so please excuse the typing errors.

heres a bit more information. the vehicle's ignition control module produces 200 pulses per min for every 100 rpm that the tachometer displays. the tachometer has a control circuit with a IC (toshiba T8557E, i cant find a datasheet anywhere!) that converts these pulses into whatever signal this motor needs to display the proper rpm. i'm applying voltage to the wires going from the ic to the motor.

what would really be nice is if i could find a datasheet for this ic but google yields no results... any suggestions on that?

Also! the coils are stationary and do not move with the needle.

oops, i guess i posted this question twice some how. bldc is what i was thinking too but there no hall sensors on or around the motor. the motor fastens to the cluster with 3 screws (each screw holds the motor in place but also acts as a terminal) which connect to a short ribbon wire that connects to the control board a little ways away from the motor itself.

If the motor is coupled to the drum below it, it is an ordinary eddy current coupling to the tacho shaft and pointer. For a beginners lesson in automobile metering, 1, the pointer needs some spring to return it to zero in the absence of a driving force. 2, the driving force is normally magnetic although some older style meters use the expansion/contraction of a wire getting hot. Going back to the magnetic drive, this could be provided by the attraction of a coil attached to the meter's pointer spindle acting on a fixed magnet or magnetic material or can be provided by rotating a magnet close to a disc that is attached to the spindle of the meters pointer. This system was the de-facto speedo drive for the last 60 years. This form of drive I think is being used for your tacho.
Frank