Timing Components ID

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JDR04

Joined May 5, 2011
367
Hi eveyone, bought this IR detector from EBAY and have tested it. So far it does the job I need it for.

I would however like to reduce the "on time period" from 20 seconds to about 5 seconds but dont know which components I should change. At a guess I think it would be a resistor or capacitor, maybe both??

Does anybody have a schematic for this device by any chance or, can you suggest how I would go about identifying the correct parts.

Heres a link to it on EBAY.

http://www.ebay.co.uk/itm/Mini-Port...Equipment_ET&hash=item35ccda96c2#ht_642wt_932

Unfortunately the IC is unmarked so I'm not able to ID that either.

I have attached photos of it hoping they help in some way.

Thanks a lot - JDR04
 

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THE_RB

Joined Feb 11, 2008
5,438
It's not a 555 timer as pin 8 is +pwr and pin 5 is gnd. That also rules out most dual opamps whoich would have been my next guess.

Re which is the timing cap, I would try C4 on the top of the PCB which seems to attach to pins 3 and 4.
 
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