Cheap Timer

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blackcat Participant Join Date: Feb 2010 Posts: 3	Cheap Timer 02/07/2010 7:16 AM
	Looking for very cheap timer circuit Spec Supply is 9v needs to be activated by simple push button (no hold) & have a switch selector to enable timer to operate for 1 min, 5min & 15min. Looking for this to be extreemly small due to space avaialble so No relays Thanks
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JohnDG Guru Join Date: May 2006 Location: Reading, Berkshire, UK. Going under cover. Posts: 9684 Good Answers: 468	#1 Re: Cheap Timer 02/07/2010 8:04 AM
	What accuracy do you need? If you don't need much the simplest circuit would be an RC circuit driving a UJT, 555 timer or similar - when the capacitor voltage charges up to the gate threshold the device turns on. Pushbutton discharges to start new cycle. Switch selects appropriate RC combination for required delay. __________________ "Love justice, you who rule the world" - Dante Alighieri
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blackcat Participant Join Date: Feb 2010 Posts: 3	#2 In reply to #1 Re: Cheap Timer 02/07/2010 8:23 AM
	Accuracy not critical, would I need 3 seperate resisters for the individual times & how big a capacitor would i need? Any circuit diagrams available?
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JohnDG Guru Join Date: May 2006 Location: Reading, Berkshire, UK. Going under cover. Posts: 9684 Good Answers: 468	#3 In reply to #2 Re: Cheap Timer 02/07/2010 8:34 AM
	No time to give full reply - google "555 timer" - plenty of circuits there. __________________ "Love justice, you who rule the world" - Dante Alighieri
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JohnDG Guru Join Date: May 2006 Location: Reading, Berkshire, UK. Going under cover. Posts: 9684 Good Answers: 468	#6 In reply to #2 Re: Cheap Timer 02/07/2010 6:44 PM
	Found what you need from the search? BTW What is it for? __________________ "Love justice, you who rule the world" - Dante Alighieri
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Anonymous Poster	#4 Re: Cheap Timer 02/07/2010 12:46 PM
	What are you trying to do with this very cheap... very small timer blackcat? You're not looking to make things go BANG are ya?
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blackcat Participant Join Date: Feb 2010 Posts: 3	#5 In reply to #4 Re: Cheap Timer 02/07/2010 3:16 PM
	Not looking for things to go Bang as you suggest! Not on purpose anyway!!! the only thing that might go bang is the 555 chip due to my soldering.
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Anonymous Poster (1); blackcat (2); JohnDG (3)

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