Capacitor charge trigger

[Kisen]

Power wise from the coil i plan on using for testing (a ECO 200)
https://www.farnell.com/datasheets/...je2XQPzYE6fZUJLHPYacLBQZmN9DY77IaAnVUEALw_wcB

It says that each actuation will give off 120 … 210 µJ @ 2 V. (with the correct circuit, rectifier and dc/dc)
I dont know the maths to work out how many actuations it would take to fully charge up a 40F capacitor. Or at least to charge it in this case to 2v.


I think i am right in that 40F @ 2V is 80 Joules.

From the generator assuming even 100uJ per actuation that 1,000,000 / 100 = 10,000 actuations per joule. So 800,000 actuations to charge this supercap about half way.
If i have these numbers right, then .....WOW....

 

[Nigel Goodwin]

The tracker aspect isnt yet determined, i would love to use a GPRS tracker, possibly with GLONASS built in, but as you say they are power hungry. Another option that seems to be coming in quite well is LoRa. This is low power (dont have any exact figures) and long range.

It rather depends on your understanding of 'long range'

As far as I'm aware it's 'long range' in comparison to the 25m range of the push button mentioned earlier - and while it may be possible to 'hop' via a network of them, it limits you to where you might be in range of any such network.

 

[Nigel Goodwin]

From the generator assuming even 100uJ per actuation that 1,000,000 / 100 = 10,000 actuations per joule. So 800,000 actuations to charge this supercap about half way.
If i have these numbers right, then .....WOW....

That's why I've repeatedly mentioned getting the generation system sorted out before worrying about anything else.

How is the generator actually going to be activated? - presumably the specification is for a specific type of movement, and the maximum that can be generated?.

 

[dr pepper]

I used the brownout reset function on a recent project.
The system was powered by a dynamo and had a slow rising power on voltage, and the code wrote to the chips eeprom so I had to use the undervolt reset to prevent the eeprom from being messed up.

 

[industry]

Interesting topic. I like the idea of charging the capacitor through the resistor and monitor the capacitor voltage. I think you should prefer rechargeable batteries instead of capacitors.

 

[gary350]

This reminds me of the NSA new bugs. Bugs listen and store people talking into a zip file when zip file is full, ZAP it sends in 1/1000th of a second it sounds like static if someone listening hears it.

 

[popper]

You will also need to limit the dischare rate of the supercap as well as overvoltage on the charger (flame hazard). The real problem is turning the cap/reg ON. Standby on uP isn't zero. You could use a switch FET (if timed, add a cap) but the FET must stay off when not needed. (i.e. gate/source R), possibly powder by watch battery? Spring mounted weight for the charger. You will also have to find the leakage rate of the supercap. I used a one Farad cap but leakdown would take years at normal temp.