Hi all,
This is my first question here and I'm not an EE so please bear with me. I'm trying to temporarily disable the countdown function of a 4060 ripple timer by jumpering pin 11 (clock) to Vss (pin 8). This does, in fact, place the countdown on hold while pin 11 is shorted to Vss, but when the jumper is removed, all countdown times are reduced by 50% on the first cycle i.e. if I'm using the ~15 second output on the chip as the countdown time, it is now 7.5 secs. This only happens on the first cycle after the jumper is removed - all subsequent intervals are back to their normal, expected times. I know I'm describing this poorly, but has anyone seen this behavior from a 4060? Thanks for all advice!

 

If possible, you should post a schematic of the 4060 connection.

Are you using the self oscillator clocking arrangement on Pin 9,10 & 11 using two resistors and one capacitor for oscillation? If so, what are their values?

 

Thanks for the reply!
Unfortunately, the schematic isn't available to me. The 4060 is used in a PIR sensor unit manufactured by Quorum:
http://www.goldmine-elec-products.com/prodinfo.asp?number=G4567
There's a PDF on this link that explains the operation of the PIR.

Here's the application -
I've been using these in a Halloween display to trigger various animatronic props when a person approaches. I developed a circuit that activates a MP3 player, and this circuit attaches to the 9VDC output of the sensor. I've hacked the 4060 in the PIR to use 30 and 60 sec. reset intervals instead of the factory-set 15 secs and 15 mins. These times are more useful for prop control. When the PIR triggers the MP3 player, the 4060 starts its countdown. This time runs concurrently with the playback of the sound file. This limits me to using sound files that are shorter than the reset time of the PIR, because if the PIR triggers again during playback, the MP3 player will be shut off prematurely.
So, what I need to do is to disable the 4060 for the duration of the sound file playback. I can do this by using a relay that shorts pin 8 to pin 11 and stays energized during the playback time period, but when the 4060 is re-enabled, the first reset time interval is 50% of what it should be. As mentioned, subsequent reset intervals are the correct time length.
Thanks for reading this long-winded post, but I think it helps to get an idea of the application.

 

You have described your problem clearly. Unfortunately, without a circuit diagram, its hard to know what signals are coming into the 4060 pin 11 or what the manufacturer has done to change the resistor/capacitor value to achieve the original 30 minute delay timing.

I would suspect the short timing is caused by signals external to the 4060 as 4060 is just a simple binary counter. If you have a frequency counter, you can monitor the frequency at pin 9 after you have released the relay and see if the frequency is different with subsequent timing cycles.

 

Thanks again for the info. I may have a frequency counter at work - I'll look into this today.