DIY old-school dashboard (with analog gauges)?

Other Hardware General Electronics
1

Hi all!

Im playing with a ludicrous idea, to fit a tiny dashboard to my bike, and control its gauges from arduino.

I have a project that might be upgraded with this dashboard, but at this moment, the question is merely out of curiosity, not a practical application (yet).

Ive been having these ideas for a bicycle dashboard for years, and most of the time ive concidered a RC servo, fitted with a gauge needle at the back of the speedometer gauge, taken from a 30 year old car (volvo240).

But nowdays ive been thinking more of project economics, keeping resource usage to a bare minimum, and that includes battery usage.

A RC servo is always using up current, even if its not moving, and i cannot simply turn it off between updates, since it would need to find its endpoints before updating the position (sweeping left/right, then finding its target).

So my question is, how would you guys set up a analog gauge controlled by a arduino?

Would stepper motors be more economic on the battery?

Are there other devices out there that could be used for this application, and that arent powerhungry?

IF and when i do build a gauge dashboard for my bike, it will probably hold 4 gauges, speed, distance(with resettable tripcounter),rpm (cadence) and battery state (voltage), in case this makes any difference for your suggestions.. :slight_smile:

2

You can get the tiny stepper motors used in modern automotive gauges. They're called "swisstech" or something like that. They are optimised to drive needles so their power consumption will be much lower than a servo.

An LSD screen can draw gauges much easier than you can build them. Get a reasonable size screen and you can do it all on one device. If you really want it to look like analog gauges, cut circles in a piece of aluminum, paint it black and put it over the screen.

3

Hi,
Can you fit This Type stepper?

Here are the dimensions:

People have used these to make temperature / humidity / time displays. They are geared so will definitely stay in position when powered off.

Lots of info and code examples here:
http://arduino-info.wikispaces.com/SmallSteppers

4

Terry; that specific stepper seems a bit too big for my liking, i was hoping for something smaller..
But im not picking components at this instant, im merely doing research in case i decide to add analog gauges to my bike.

im hoping for a dash gauge roughly around 3-4 cm in diameter and the gauge housing should be less than 5cm in depth (dial face <-> rear plane).

I know, im pretty much describing a LCD here, but im not! :slight_smile:
i love that physical needle moving around the "clock face".. :slight_smile:

MorganS: I belive LSD makes ANY surface into a display, totally without any wires.. The problem is to create a repeatable user interface thats pre-defined, and not made up as you go.. :slight_smile:

Thanks for the tip tho, i did try to search for "swisstech" but it appears to be a company name, not a part name.
I did however find this:

Witch seems to be pretty much perfect for me, if one were to overlook the pricetag (and the need for driver card).

A stepper motor does seem to be the best option, especially since modern vehicles are using digital dashboards, meaning i might be able to salvage these components from the car salvage yard nearby.

5

Hi,
That Adafruit motor is the same size (but not as deep).. as the one pictured above. And it's $5 with the driver. These are widely available.

6

What about a standard d'Arsonval meter movement driven by a PWM signal? Totally passive. And, it could indicate multiple values since the input signal can be selected by the Arduino.

YMMV

7

Indeed analog meters are available with as little as 50uA full scale (although they would be more
delicate - certainly a 1mA or so movement should work, but they never have more than about 90-100 degrees
of movement due to the design.

8

The stepper that @MorganS mentions is: Switech x27
It used in many cars for gauges

9

Here is a link to a driver board for a Switech stepper.

They also have some links to software and Arduino example sketches.

10

Automotive gauge stepper motor with indicator needle

11

5V/200 ohms = 25mA. So you can drive these directly from the Arduino pins, but make sure to include protection diodes. It'll take four pins emulating an H bridge driver.

http://www.edn.com/design/automotive/4430046/How-to-implement-a-stepper-motor-driver-for-smart-gauges-Part-I

You can easily duplicate this design:

It is open source hardware and software.

Interfacing to the Arduino Uno and Mega is made easy using Guy Carpenter’s SwitecX25 library here: GitHub - clearwater/SwitecX25: Arduino library for Switec X25.168 and friends

In fact, a single Arduino Uno can run up to 3 motors at once.

If you buy a bunch of the steppers at once, they are much less expensive. Six for $16 with Amazon Prime shipping:
http://amzn.to/2vG2skP

12

The way they generally work is the first thing done on bootup is to run it CCW far enough that it will always stall on the stop, no matter where it started. Then as long as it does not lose steps, your software can keep track of where it is.