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Relay timer 2 min on and 10 min off, and repeat constantly.

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Clarkdale44

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Hello

I want to make an auto relay timer circuit such that it turns on the load connected to the relay for 2 min then turns off for 10 min and repeats this cycle indefinitely.

I have a few 555 timer lying around was hoping if could make something out of it. The timings doesn't needs to be absolutely accurate, just near 1-3 min on time, and 10-12 min off time.

Would appreciate if you could post out schematics with fewer parts as possible.


Regards!!
 

Reloadron

Well-Known Member
Most Helpful Member
What you seem to want is a repeat cycle relay timer which could likely be done using a few 555 timers or a 556 timer. However, in the interest of keeping things simple and affordable even though you may have parts, I would consider a simple turn key solution like this one. A simple Google of "Relay Timer Module" will bring up literally dozens of hits with most being inexpensive modules off the boat from China. There are US made units from companies like Macromatic suitable for industrial applications but for a simple hobby project the Chinese stuff works fine and many include a LED display.

Just My Take
Ron
 

AnalogKid

Well-Known Member
Most Helpful Member
As above, ebay and amazon have many variations of relay timer modules. Put the word 'cycle' somewhere in the search field.

If you really want to build a circuit from scratch, then one 555 astable circuit can do what you want - on paper. The total cycle period is 11-15 minutes, a looooong time in R-C timer land. Multi-minute R-C timers are not very stable, and their performance changes with temperature and aging.

I recommend a counter-based circuit rather than one or two 555's. Look into the CD4060 oscillator/divider. My first thought goes like this:

1 - CD4060
2 resistors (oscillator)
1 capacitor (oscillator)
1 capacitor (decoupling)
2 - 1N914 or 4148 diode (decoding)
1 - 2N7000 (relay driver)
1 - 1N914 (relay coil suppression)

The total body count is less than that of two 555 monostables in a series loop, and almost equal to a single 555 astable circuit.

ak
 

schmitt trigger

Well-Known Member
Of course, the smallest and fewest parts would be a small 6 pin microcontroller....but I assume that you would like to use discrete logic.

So AK's suggestion would be by far the simplest one. The CD4060 also allows to reset the count.
 
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