# Timers



## Madman (Jan 5, 2008)

I have two operating cars that I built some time ago. One is a radar car, where the radar antenae spins and LEDs light up on a control panel. The other is an aquarium car where a mermaid swims continuosly in a circle. At present they both run on battery power. The radar car uses a nine volt battery, while the aquarium car uses a AA cell. I am in the process of finding ways to have these cars operate only when they pass over a track magnet. Having them run continuously drains the batteries too quickly.I have found these timers on Ebay, and would like any electronic rocket scientists here to have a look at them. I not sure of some of the terms used. For instance, the pause time. Would that be the time the device closes the normally open contacts?

Basically, I would like to know how these timers operate. 

[url]http://www.ebay.com/itm/181011745938?ss … 1438.l2648[/url]


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## Michael Glavin (Jan 2, 2009)

Dan,

I’m know scientist, but that is a "delay on make timer", which means once powered the timers clock starts and energizes the contacts after the user adjustable time parameter expires. Thereafter the contacts are engaged indefinitely.
Michael


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## toddalin (Jan 4, 2008)

Do research on 555 timer chips, the workhorse of the industry. Plenty on the 'net.
BTW, you can easily modify that ebay unit to do any time span you desire by changing the value of the capacitor and/or resistor.

Of course you could also just use two relays, a reed switch and your battery. Passing the magnet turns it on, passing again turns it off, etc.


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## Madman (Jan 5, 2008)

Posted By toddalin on 05 Nov 2012 06:24 PM 
Do research on 555 timer chips, the workhorse of the industry. Plenty on the 'net.
BTW, you can easily modify that ebay unit to do any time span you desire by changing the value of the capacitor and/or resistor.

Of course you could also just use two relays, a reed switch and your battery. Passing the magnet turns it on, passing again turns it off, etc.


Thanks. What type relay would I need? I watched some tutorials on Youtube about 555 timers. It seems that they are used more for blinking circuits. I need the animation to last for at least 30 to 60 secons.

What about something like this?

http://www.ebay.com/itm/Two-DPDT-Si...3f1eb46aa0


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## toddalin (Jan 4, 2008)

Thats fine if you are running a PIC.

In the last Garden Railways Magazine they ran my article on how I animated Gustav to push a block of ice into a reefer hatch. In that case the 555 is used in bi-stable (flip-flop) mode. 

This is how the 555 is used for a automatic reversing circuit, again in bi-stable mode.



This shows the chip used in mono-stable (one-shot) mode and is the circuit (portion on the right) that I use on the Tortoise Bump Accident Sentinental System (Bump A.S.S.) used to protect my crossing. This is what you want to do but you won't need the voltage regulators or wheel detectors. Sorry about the quality.



Here is how you can simply use two relays for an on/off.


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