This is our "official" Learn to Surface Mount Solder kit! It's got a "Practice Stalks" area on the back where you can solder rows of 1206, 0603, and 0402 resistors and capacitors, as well as mini-melf and SOD-323 diodes. On half of the footprints, one pad is tied to ground, which gives you experience with soldering to pads with some heat sinking. You might be asking "but what about 0805s?" Well those are part of the actual circuit! It's also part of our Fun with 555s series, and uses 2 dual 555 timers and an inverter to create 5 different blink rates, one for each flower. You can make your flowers whatever color you want (or multicolor!), just be sure to match the LEDs with their corresponding resistor values. We hope your SMT soldering skills flourish and grow with this cool kit!
The circuit configures all four 555 timers in a circuit called an astable multivibrator. Basically, it generates a repeating square wave at a particular frequency. The duty cycle for the square wave is short though, and putting it through the inverter chip not only increases the time that the LED is ON, but also allows the inverter chip to provide the current to drive the LED (555 timers are notoriously poor suppliers of current, especially at low supply voltages). The fifth frequency is generated by sending 2 of the previous ones through two inverters which are diode-OR'd together. So it's only off if both of the parent signals are off, and it's brighter when both parent signals are ON. It gives it a nice flickering effect!