Unusual LED Blinker

This LED blinker manages with only a few components and is dimensioned to operate from an ac supply in the range of 4–16 V (6–24 V dc). As its current consumption is less than 1 mA, it’s also suitable for long-term battery-powered operation. It thus offers several advantages in various applications, compared with using the well-known 555 timer IC as an astable multivibrator. Depending on the values of the timing components, the blinking rate ranges from 1 to 1.5 Hz. Although the duration of each blink is only a few milliseconds, a high brightness level is achieved by using a relatively high LED current. There are numerous potential applications for this circuit in model railway systems, in both stationary and moving equipment.

Resistors:
R1 = 22kOhm
R2 = 10kOhm
R3 = 68kOhm
R4 = 22Ohm 
Capacitors:
C1 = 47µ F 35V
C2 = 10µ F 25V
Semiconductors:
D1 = 1N4148
D2 = low-current LED
THR1 = BRX45
Miscellaneous:
PCB, order code 040056-1 from The PCBShop