Anyone build the add on refresh circuit?

coyotebandit

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I remember seeing an add on refresh circuit for the older JoeD timer. I was wondering if anyone has built it, and if they have tried it with the OWL PF? I think it consisted of a 555 timer and an opto-coupler?
 



Brian

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I believe Tinhorn did this.

If my memory serves me right it is just a 555 timer in astable mode with a seven minute timing cycle.

Radio Shack has 555 timer books with examples of how to build all kinds of circuits using a 555 timer.

Fun stuff to play with when you are starting out.  The current drain is not optimal even from the low power version of 555's.
 

Hill Hopper

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I'm trying to build it right now, and having trouble getting it to run on my breadboard. The schematic on the right side of the opto is not very clear. I guess I'm going to have to just play with it.

Butch

Guess it won't work w/o a relay. DUH

(Edited by ****** at 9:26 am on Mar. 22, 2002)
 

shrtcirkt

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HillHopper,
Are you using an opto coupler to trigger the refresh? If so, one thing to remember about opto couplers is that they are polarity sensitive.The input side is a LED and the same rules apply, resistor in series to reduce voltage, and + side to the anode.
On the output side of the opto you basicaly have a transistor, so the same applies keeping in mind that current flow is based upon whether the output transistor is a NPN or a PNP type.
I am not certain, but all the pics I looked at in my Mouser catalog indicate that current flow would be from pin 4 to pin 3 on the output side.
If Brian reads this he may make a correction if I am in error.
HTH
 

Tinhorn

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Here is the Latest Refresh Circuit I've been using with JoeD's old Timer.

http://www.nightowl.net/~tinhorn/JoeDRefresh.jpg

The Schematic shows how to wire the refresh circuit to a relay.  This relay don't nesessarily have to be attached to a timer but can be the one connected to a PIR, just wire the contact side of the relay as shown.

I have built 2 of JoeD's timers with this circuit and they've been working fine.  Check out the Squeaker Post for the Bobcat pix I got for the latest pix's using this circuit....


The timing resistors are some I had in my Junk Box, RS don't sell the exact values so you may have to purchase several that add up to these values and solder them together in "Series"

Tinhorn
 

Lew

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I am learning as I go along.  So far I have ignored posts about refresh circuits since I figured I didn't need one and wanted to keep thinks as simple as possible.  Would someone please explain why a refresh is needed.  And if using a Owl PF, is a refresh an added benefit. Thanks.  Lew
 

coyotebandit

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You don't need one in the daytime, but at the nightime it reduces the delay involved in charging the flash capacators, especially in colder weather. For example I have a pic in the snow with fresh deer tracks in it, the deer was out off the picture by the time the camera went off, I'm hoping that a refresh circuit would fix that!
 

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