Hello there,
I am using sets of copper thin lead LED fairy light strings for my kitchen & bar benchtops, mirrors etc. They are usually operated from 3xAAA batteries (so 4.5V) but of course do not last very long on batteries so I have attached 5V mains adaptors (ordered 4.5V adaptors as well now but 5V is a lot more common due to Phone etc USB charging).
I'd like to keep the control boxes (which hold the batteries normally) for the LEDs due to the included timers (6hrs on, rest off, cycle). The prob is of crs that if the power fails, when restored, the LEDs never come on (one needs to press a button on the controller to turn them on perm or on timer) or they come on permanently. So I would like to have 3xAAA rechargeable batteries in the housing as backup for temporary power failures.. The problem is, I have no idea what circuit to use, preferably a very simple, few components one that fits inside the case as well (maybe). So I would like the rechargeables to be trickle charged permanently (or the charge to switch off when they are full but to restart of course when charge drops).
Any suggestion for a simple circuit I can build for this purpose (maybe a link etc)? So feed in 5V or 4.5V DC, power the LEDS but also trickle charge / keep charged the rechargeables for eventual power failure so the timing is not lost.
Right now I have just soldered the adapter terminals on top of the battery terminals for the fairy lights and for the LED candles, I have fitted DC sockets that switch off the battery side when the DC plug goes in. All good... until the power fails
Many Thanks!
PS Of course I can have mains timers switching the power adapters - I am using that for some 'dumb' LED candles (no own timer). The mains timers have battery backup themselves so they do not lose the timing info, but still the candles do not light up of course if mains is not present.
PPS some lights use 3XAA, probably no difference int the trickle charge circuit (?)
I am using sets of copper thin lead LED fairy light strings for my kitchen & bar benchtops, mirrors etc. They are usually operated from 3xAAA batteries (so 4.5V) but of course do not last very long on batteries so I have attached 5V mains adaptors (ordered 4.5V adaptors as well now but 5V is a lot more common due to Phone etc USB charging).
I'd like to keep the control boxes (which hold the batteries normally) for the LEDs due to the included timers (6hrs on, rest off, cycle). The prob is of crs that if the power fails, when restored, the LEDs never come on (one needs to press a button on the controller to turn them on perm or on timer) or they come on permanently. So I would like to have 3xAAA rechargeable batteries in the housing as backup for temporary power failures.. The problem is, I have no idea what circuit to use, preferably a very simple, few components one that fits inside the case as well (maybe). So I would like the rechargeables to be trickle charged permanently (or the charge to switch off when they are full but to restart of course when charge drops).
Any suggestion for a simple circuit I can build for this purpose (maybe a link etc)? So feed in 5V or 4.5V DC, power the LEDS but also trickle charge / keep charged the rechargeables for eventual power failure so the timing is not lost.
Right now I have just soldered the adapter terminals on top of the battery terminals for the fairy lights and for the LED candles, I have fitted DC sockets that switch off the battery side when the DC plug goes in. All good... until the power fails
Many Thanks!
PS Of course I can have mains timers switching the power adapters - I am using that for some 'dumb' LED candles (no own timer). The mains timers have battery backup themselves so they do not lose the timing info, but still the candles do not light up of course if mains is not present.
PPS some lights use 3XAA, probably no difference int the trickle charge circuit (?)