Solar "enabled" boost converter

LED ribbon strip light can be very useful, It comes supplied on a reel,
you simply cut it to length, affix with its self adhesive backing,
connect to 9 to 12 volt DC and it works.

I needed to run some LED ribbon from a 6 volt battery DC supply.
Direct connection doesn't work because of the fact there are groups of 3 led's in series,
'bussed' together along the length of the strip
meaning in excess of 9 volt (3 x 3v) is needed to 'strike' the LEDs.
I overcame this drawback by use of an XL6009 boost-convertor circuit (as shown).
which boosts up the 6 volts to 12V or so, and will light the LED ribbon strip.



I also needed to flash/blink the LED's .
I did this using a cross-coupled (Eccles-Jordan) multivibrator
constructed from discrete components. Output is a "square wave"
With circuit values shown: freq' is approx 1 Hz. (see formula)
An "enable" pin on the XL6009 is clocked by the multivibrator and causes the LED's to flash.
I also needed automatic turn-on/turn-off at nightfall/sunrise.
By connecting a small solar cell (3V max) to one transistor base thru a 3K3 resistor,
solar enabled switch on/off is acheived!
Solar cell is re-purposed from a cheap $4 garden lamp.
When the solar cell is illuminated; the -ve voltage bias to the transistor base, disables operation.



� 2Q 2019