Energy effecient Low Frequency Low Duty cycle LED blinker

[ThinkPad]

Hi,
I have seen other posts about LED blinkers but cudnt find any that fit my req. I am looking for to save energy by blinking an LED for a very short duration (abt 150ms) at a low frequency of 1Hz or less. Using 555 astables with such a large period has a downside of large leakage currents etc. Please advice
Thanks a million in advance

TP

 

[(*steve*)]

Look up the LM3909.

 

[blocka]

If you are after something that is really lower power try something like a NC7SZ14 schmitt trigger inverter. You then place a cap on the input pin to gnd and a resistor from the output to input. This will give you 50% duty cycle so would need to have a diode and resistor from output to input in different direction to acheive different duty cycles.

It depends on what you mean by low power. Obviously the LED is going to be the dominant component in power consumption anyway.

 

[(*steve*)]

The LM3909 dumps the energy from the timing capacitor through the LED during the discharge phase. A circuit that operates in that manner will put the energy in the timing capacitor to use and thus has the potential for lower overall power use.

Low power oscillators are comparatively easy -- it's having them flash a LED and maintain their low power operation that is the trick.

Here's a couple that use either low LED current and/or low duty cycle to do the same thing a and b and of course c.

It might be interesting to see if you can use a single schmitt trigger set up as a variable duty cycle oscillator, but with one of the diodes (the discharge one) replaced with a LED. You'd probably have to operate it above 5V so that Vf of the LED is below 1/3Vcc (maybe a 40106? -- but it's a hex schmitt trigger)

 

[ThinkPad]

FAN5645MPX LED blinker

Hi,
Thnks for your help. I came across a LED Blinker - FAN5645MPX. Its a little more complicated to use cos u have to record the sequence.
A relatively inexpensive option though .

Regards,
TP

 

[(*steve*)]

Just be sure that you can use something in that package -- it looks pretty small.