Who's good with 555 Timers?

[DashApple]

And I presume the output is 5V ?

Yes , Logic voltages are 5V max

 

[ped]

I edited that post, have a look

 

[ARG]

  ontime = 5;           // time in seconds to be ON
  timeperiod = 60;         // time in seconds to be ON + OFF

Change these two lines in Sig's code to whatever number you want for on and off cycle

 

[Sigurthr]

Yup all the above advice is correct. Glad you got it working! It's hard to find micro/nano sized ones without the CH340.

D3 is Digital 3, yes it needs a pass transistor, especially for the Micro/Nano boards as they can only source/sink ~7mA.

Set those two lines to "3" and "6" respectively for a 3s on 3s off test run. (I tested with a 5/10, 5/15, and 5/60 split to verify performance).

edit: you can set those two variables to whatever you want (in whole numbers under 32767) as long as you follow one condition:
timeperiod must be larger than ontime.

If you want precise timing, timeperiod should be the ontime plus the offtime.

 

[ped]

Well it's all working now..Google recommends using TIP120's as pass transistors , so I'm adopting the following circuit, as I like the idea of it being opto-isolated.

Ped