Valentine Heart Project

This project flashes 18 LEDs at three different rates and you can use these to create an eye-catching Valentine Heart. The circuit is kept simple (and low cost) by using the 4060B IC which is a counter and oscillator (clock) in one package. The circuit requires a 9V supply, such as a PP3 battery. It will not work with lower voltages and a higher voltage will destroy the LEDs.

The preset variable resistor can be used to adjust the oscillator frequency and this determines the flash rate of the LEDs. The IC limits the current to and from its outputs so the LEDs can be safely connected without resistors in series to limit the current. The stripboard part of the circuit is easy to build but the wiring for the LEDs needs care so detailed instructions are provided below.


Warning!
Using a battery (or power supply) with a voltage higher than 9V will destroy the LEDs.
You can see from the circuit diagram (below) that 6 LEDs are connected in series between the +9V supply and 0V. Each LED requires about 2V across it to light, so using a voltage of about 12V (= 6 × 2V) or more will make the LEDs conduct directly, regardless of the 4060B IC. With no series resistor to limit the current this will destroy the LEDs.

Parts Required

1. resistors: 10k, 470k
2. preset: 47k (this could be 100k if necessary)
3. capacitor: 0.1µF
4. 4060B IC
5. 16-pin DIL socket for IC
6. LEDs × 18, 5mm diameter, red (or any mix of red, orange, yellow and green)
7. on/off switch
8. battery clip for 9V PP3
9. stripboard 13 rows × 18 holes

Circuit diagram