using 556 as two separate time delays

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Joined: Tue Feb 26, 2008 12:08 am

using 556 as two separate time delays

Post by vandyo » Tue Feb 26, 2008 12:17 am

Hi I'm new to this forum and would like to request help in using a 556 as indicated in the title. I do not know a lot but do tinker with circuits. I currently have a circuit using two 555s, the first for a time delay & subsequent activation of the 2nd. The 2nd also provides for a reset of the 1st when reqd. This circuit works fine but I need a 3rd timer for a new function so I am trying to use a 556 as the delay timers and leave my 555 circuit as is as it works well.

I have searched & been unable to find examples of this, but did find a Philips data sheet on the 556 as a sequential timer. (.gif attached) I have been able to duplicate the 'A' side to perform my delay ok. The only change made to it was to not use the output pin5 to feed the input pin8 of the side 'B' as I did not want sequential timing. I have not been unable to use or modify the 'B' side to work in a time delay way. Since this schematic is for sequential timing, do I neet to modify it further to have side 'B' work as a separate delay timer.

I did use another 556 on a diff breadboard & did only the 'B' side but still no luck. Would appreciate any help of comments.
556Seq DualTimer.GIF
556Seq DualTimer.GIF (5.02 KiB) Viewed 4479 times

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