'Aloha Friends!

I seek suggestions for a joule thief circuit that will shut it self down then a certain output voltage, say 3.3v, is reached on it's output storage capacitor? It should stop drawing current from the supply - no need to deplete the source more than necessary.

It is for an IoT sensor that I would like to power from a single, at times quite depleted, AA cell. Circuit needs 3.3v but is in deep sleep most of the time.

Of course it doesn't really have to be exactly a joule thief, it is just a well known concept to put the need in a perspective.

/mogul

 

Under what conditions do you want the JT to start up again after shutting down?

 

mcp1623 solution

 

A JT is basically a switchmode power supply. A fairly crude one at that. There are much better solutions that will provide cleaner power than a JT and are easy to shut down. The mcp1623 could work but you will need to understand how much current your IOT sensor will draw at peak times. When transmitting, it need more than several hundred mA.

 

Under what conditions do you want the JT to start up again after shutting down?

I had hoped for the JT to start when the voltage had dropped somewhere below the desired output voltage, probably with some hysteresis.

 

...you will need to understand how much current your IOT sensor will draw at peak times. When transmitting, it need more than several hundred mA.

It is based on an atmega328 and a RN2483 radio, so according to datasheets it should be less than 50mA. I measure less, but thats probably just my multimeter not reacting fast enough.

 

Under what conditions do you want the JT to start up again after shutting down?

An interesting chip. Unfortunately I haven't found it as a hobbyist friendly module to an affordable price.
I had hoped for something I could hack together on a piece of proto-board with "generic" parts. Thats the beauty with the JT - you can get it to work with almost whatever you throw at it.

 

The mcp1623 would work for you with that current draw. I was thinking of something like the ESP chips.

Given that most of the interesting chips are available only in SMD packages it makes sense to learn how to use them. Fortunately, it's pretty easy. You can get SMD proto adapters that plug into solderless BBs and in a pinch can use "dead bug" style (mount upside down with little glue, solder thin wires to the legs). Also, getting PCBs made has never been faster nor cheaper.