Low voltage timer

Hi all,

I’m a software designer, but I’m quite new to electronics. Can anyone give me some advice on how to build a basic timing rig that outputs an ‘on’ signal when triggered?
Basically I want to use something thats low-friction and low-power consumption to time a small rotor.

My idea so far is to use a small IR range-finder such as this:
and output a simple ‘on’ trigger when the rotor cuts through its optical path. Do I need an orangtang board to control the signal? Or can i simply output this IR finder to another input such as a LED or servo?


I am not sure I understand what you are trying to do. Can you describe your rotor mechanism in more detail (a picture or diagram would be useful too)? How do you intend to use the output of this circuit? If you tell us more about your project, we might be able to give you a better idea of whether the digital distance sensor will work for you or offer you some alternative ideas.

If you just need to power an LED or something else that only draws a few milliamps of current, you might be able to connect it directly to the sensor (we sell a carrier board for the digital distance sensors that has a built-in LED). To interface with something that requires more current or a more complex control signal (like a servo), though, you would probably need a microcontroller or some other intermediate circuit; the exact choice depends on what you want to control.

- Kevin

I’m trying to keep it as basic as possible for power consumption.

Basically put, I need it to trigger a simple stepper-motor everytime the rotor revolves once.

So my thinking was to attach the sensor underneath the rotor and have a black marker for the reflectance sensor to trigger directly out to the stepper-motor.
Should this work by connecting the output directly into the stepper motor?
Is there an easyier way of sensing a revolution on the rotor with switches or something?

The sensor you linked to in your first post was a digital distance sensor, which is meant to detect the presence or absence of an object in front of it, but we also have reflectance sensors (which you mentioned in your last post) that you can use to detect brightness differences on a surface instead. Without knowing more about your rotor, I cannot tell which one would work better for you (or suggest any other alternatives).

You definitely cannot control a stepper motor directly with either of those sensors; you would probably need to use a stepper driver and some kind of microcontroller, programmed to read the output from the sensor and generate the appropriate signals for the stepper driver.

- Kevin