How do i make a timed switch?

I need to create a timed switch (about 8 hours long) that will turn on when the user presses a button and turn off 8 hours later. i don't know voltages... so i just need possible parts. its for a boiler, so it will probably be 12-120 volts.

Update:

Can i get the IDEC RTE at lowes/home depot? or do i need to order it online? thanks!

Update 2:

The control circuit is 120v. just adding details as i find them.

2 Answers

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  • Jingo
    Lv 4
    9 years ago
    Favorite Answer

    This is kind of funny. Last week I had the same need for an air compressor. I looked around for ready made timers and did not find anything.

    So I drew up a wiring diagram to make my own timer.

    Parts List:

    1 - Momentary Normally Open pushbutton switch for Start

    1 - Momentary Normally Closed pushbutton switch for Stop.

    1- DPDT control relay with appropriate coil voltage

    1- IDEC brand RTE timer. The exact model will depend on the control voltage. http://us.idec.com/Catalog/ProductSeries.aspx?Fami...

    2- relay bases. One to fit the control relay and one for the IDEC timer.

    Wiring:

    L1 goes to one side of the of the start button and one of the N.O. contacts on the control relay.

    connect a wire from the other side of the start button to the other side of the N.O. relay contact and from there to one side of the stop button.

    From the other side of the stop button connect a wire to a N.C. contact on the timer.

    Then from the other side of the N.C. timer contact connect a wire to the coils of the control relay and the timer.

    Connect L2 to the coils on the timer and control relay.

    Use the second N.O. contact on the control relay to switch your load.

    Operation:

    press start - power passes through N.C. Stop button and N.C. timer contact to pull in both the timer and control relay. As the control relay energizes, it closes contacts in parallel with the start button which will maintain power to both holding coils.

    The timer will count from 1 sec to 100 hours depending on the setting. Once the timer times out, the N.C. contact will open. With the Timer contact open, the timer will stop counting and the control relay will de-energize.

    The stop button was included to stop the circuit at any time before the timer times out.

    Let me know if you need a wiring diagram.

    ******Additional******

    I buy IDEC relays and timers at the local electrical supply house. Hardware stores like Lowes or Home Depot do not carry these items. There are several companies that make On-Delay timers that will work. Graingers has several suitable timers listed but all of them are pretty expensive.

    I use an IDEC RTE-P1-AF20. This is for 100 to 240 VAC.

    Any timer with On-Delay and around 10 amp N.C contacts and a coil with the appropriate voltage will work.

    Here is a source online. I have ordered from Allied before. They are about $10 higher than I pay locally but Allied is fairly trustworthy. http://www.alliedelec.com/search/searchresults.asp...

    ******Yet More******

    Here are part numbers for the relay, bases and timer you could get from your local Graingers. But, like I said, Graingers is pretty high priced.

    http://www.grainger.com/Grainger/OMRON-Relay-2W919...

    http://www.grainger.com/Grainger/DAYTON-Relay-Sock...

    http://www.grainger.com/Grainger/DAYTON-Time-Delay...

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  • Robert
    Lv 4
    5 years ago

    A programmable timer is a device which can be used for switching a load ON and OFF after predetermined delays as per the requirements.

    The delay timings are adjustable according to the users personal specs. The ON time delay and the OFF time delay are independently settable and this facility becomes the most important feature of a programmable timer circuit.

    In this page we will discuss a very simple yet reasonably useful timer circuit diagram whose ON time and OFF time settings are independently adjustable through ordinary pots.

    The idea becomes so easily configurable due to the versatile IC 4060 which require minimal number of component for getting the unit running.

    Looking at the CIRCUIT DIAGRAM below we can see that two inexpensive IC 4060 have been wired up as two independent timer modes.

    However though the timing settings are independent for the two sections, these are coupled with other such that their initialization become very much interconnected.

    Basically both the configurations are similar and have been rigged in the standard counting modes of the IC 4060 devices.

    The output of the upper IC is coupled to the reset input of the lower IC via a transistor in such a way that once the upper IC's output goes high, it triggers the lower timer into operation.

    The lower IC then starts counting and when its output goes high, it halts the upper ICs counting and resets it to its original state and the process is initiated back from the start.

    It simply means that as long as the upper ICs timing does not lapse the lower IC remains idle, however once the upper ICs timing lapses and its output becomes high, it switches the output load as well as the lower ICs operation.

    The pot associated with the upper IC can be used for determining after how long the load will be switched ON, while the pot associated with the lower IC is used for determining how long the load remains in the switched ON position or simply after what time it should be switched OFF.

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