# Automatic Timed Polarity Switch and Shutoff

#### jkompa

Mar 24, 2015
2
First off thank you to anyone who is able to point me in the right direction. I am a mechanical guy and have confused myself trying to dig into circuit development.

I am looking to keep the circuit as simple as possible. I will be powering system using a wall adapter for 110V AC however I have found wall adapters to convert this to 6V DC for me which I will use in order to simplify my circuit unless someone lets me know a reason not to. The 6V DC is what is specified for the two components I am trying to run, a Micro Stepper Motor and a UV Light.

My system needs are as follows:
- External Contact Switch
- Used to connect the system (like a button to turn on)
- this contact will be separated and reapplied manually to start cycle again when need be
- System needs to run for 60 seconds and then turn off automatically
- Micro Stepper Motor (specs 6V DC and 200mA (assuming this is start-up amps) down to 20mA (assuming this is continuous running amps)
- Run oscillating while system is on as stated by the external contact switch above (60 seconds)
- approximately 6 seconds forward followed by 6 seconds reverse
- exact time isn't necessary but looking to have approximately 5 full cycles for the 60 seconds run time
- UV Light (specs indicate 6V DC and 6mA)

- Run continuously while system is is on as started by the external contact switch above (60 seconds)

I believe I am going to need a 555 timer, possibly 2. One to control the total time till shutoff and one to control the time to polarity switch on the motor which I also believe would require an H-bridge to switch the polarity. All of the samples I have seen show additional resistors, etc. which I am uncertain what are for and seem to be over complicating the circuit, so that probably just shows how clueless I am. Also I am thinking that polarity switch for the motor may negatively affect the light so does that mean I need another switch for polarity at the light?

Comments to point me in the right direction or a sample circuit diagram would be greatly appreciated.

Thanks again.

#### jkompa

Mar 24, 2015
2
Update to request, this will use just a regular DC motor not a stepper motor so just a 2 pin connection.

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