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Need a simple circuit to reset a device very X minutes
- Thread starter supak111
- Start date
What's your cost limit?
If this needs to operate on a continuous basis, ie off, on, off, on etc then the op will need to look at astable configuration.If the blt module has a reset pin the 555 should be the best option!
Anyway you can try to supply the module through the 555 monostable and see what happens
supak111
★ƃuᴉɯǝɥɔs sʎɐʍlɐ★
Yea I was thinking about using the 555. I think I just figured something out even simple and cheap. There are these $1 555 delay timer modules with a relay on them. I have a few at the house.
What if I connect it like this picture. The timer would count off say 5 minutes, it would activate the relay and because of that it would cut power to itself and restart the 5 minute countdown again...
What if I connect it like this picture. The timer would count off say 5 minutes, it would activate the relay and because of that it would cut power to itself and restart the 5 minute countdown again...
Not nearly enough. The timer changes state when the timing capacitor is charged up (to 1/3 Vcc). If you then remove power to the timer, the 555 cannot discharge the cap.
There are adjustable and programmable cycle timers on ebay that will do what you want, but 1 second out of 300 is a very high duty cycle. This is one of the reasons I don't like the 555 for multi-minute periods, but it can be done. A modified version of the standard 555 astable can be tweaked to a 300:1 duty cycle, but the timing cap will be huge and the long period will vary with room temperature.
Another way uses the CD4060 to make one pulse every 256 counts. A 5 minute cycle would produce a 1.2 second pulse.
ak
There are adjustable and programmable cycle timers on ebay that will do what you want, but 1 second out of 300 is a very high duty cycle. This is one of the reasons I don't like the 555 for multi-minute periods, but it can be done. A modified version of the standard 555 astable can be tweaked to a 300:1 duty cycle, but the timing cap will be huge and the long period will vary with room temperature.
Another way uses the CD4060 to make one pulse every 256 counts. A 5 minute cycle would produce a 1.2 second pulse.
ak
Last edited:
supak111
★ƃuᴉɯǝɥɔs sʎɐʍlɐ★
Device is a BT module with a relay on it (proximity-switch), its not just a simple little BT module. I want to keep the BT in discovery mode and that only happens first 5 mins I believe. Just cutting power to the whole device puts it back to discovery which is my goal.
BT module on it is a rda5851s I believe. If I could just reset the BT module that would be great but I cant seem to figure out what pin the reset is nor would it even reset it back into discovery mode if I did find the reset pin.
Ill take some pics of the whole device with the rda 5851s on it soon.
For now what about this:
BT module on it is a rda5851s I believe. If I could just reset the BT module that would be great but I cant seem to figure out what pin the reset is nor would it even reset it back into discovery mode if I did find the reset pin.
Ill take some pics of the whole device with the rda 5851s on it soon.
For now what about this:
So like AK says, what do you want the circuit to do?
If continuously cycle on and off you could use the 555 in astable mode.
Set your on off to whatever via rc arrangement on 555 terminals 6,7 and 2.
Forget your wiring arrangement that cuts power to the timer, leave it powered and run your bt from the relay only.
No??
If continuously cycle on and off you could use the 555 in astable mode.
Set your on off to whatever via rc arrangement on 555 terminals 6,7 and 2.
Forget your wiring arrangement that cuts power to the timer, leave it powered and run your bt from the relay only.
No??
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