Joule Thief

[crowclaw]

@ Freepow... I think I have the jist of what your are doing here so should be ok with my design... based on the principle of detecting a switch sequence, so should adapt to what you require...forgot to mention. SW1 in my diagram is your "A" switch of course. Regards

[freepow]

@  Crowclaw, I am not sure where to connect your circuit on to mine, please open my attachment diagram and have a look, thanks.

[freepow]

@  All,  Just say I have a Television rated at about 70 Watts at 240 VAC (Australia), would that equal about a current draw of approx 0.3 Amp/hour

If so, why cant we use a powerful JT with an output of 0.3 Amp with high voltage to power the TV ?
would it work ?

[crowclaw]

Hi Freepow ...You have two batterires "A" & "B" you need to build two monitoring circuits. I've drawn only one, connection V1 on my drawing is point "A" on your drawing. Next build an identical circuit and V1 then becomes "B" on your drawing of course...so when either A or B is in the off position then the RED LED's are both off. Next connect point JT1 on my drawing to your first JT's power input connection after the switch (and the same for your second JT) so when either of your JT's are switched on the RED LED's are also on! If you only want to use just one RED LED then replace one of them and with a  collector load resistor of say 10k and connect both connectors together.

[crowclaw]

@  All,  Just say I have a Television rated at about 70 Watts at 240 VAC (Australia), would that equal about a current draw of approx 0.3 Amp/hour

If so, why cant we use a powerful JT with an output of 0.3 Amp with high voltage to power the TV ?
would it work ?
[/quote Your Household supply is a very stable AC voltage with a line frequency of 50Hz / 60 Hz at 240v... your appliances are designed to match these requirements. JT circuits using ferrite cores however produce a self oscillating high frequency pulsed DC output at relatively low current. An AC inverter however can provide the necessary requirements from a 12v/24v DC supply but demand a higher operating current. You can build a simple inverter with a transformer and a few additional components to work from a 12 volt battery but again although the input voltage is only 12v the current demand is high at several amps. Regards