Party Cap With 2 Different Modes Using 4017

So my friend's birthday was close and we were supposed to have a party. I wanted to create this type of cap for some time and finally made it. It is quite simple yet elegant.

The whole system runs by a single button hidden under the fabric that activates the circuit. It has two modes:

1) Fixed on led

2) Blinking led

Another press would turn the LED off. To accomplish this I used a 4017 decade counter accompanied by a transistor astable circuit. It took just 1 day to create the whole device.

List of tools needed:

1 x 4017BE decade counter

2 x BC547 transistor

2 x 4.7uF 25V capacitors

2 x generic diode(1n4007 or zener)

1 x push button

1 x 1k resistor

2 x 100k resistor(or 1 x 47k resistor)

2 x 47k resistor(or 1 x 26k resistor)

1 x 3.7V lithium-ion battery(the thinner the better(

1 x XL6009 booster circuit

1 x 12V led strip

soldering iron, wires

4017BE: The output of this IC proceeds by one when a clock pulse is applied. I used three outputs from this IC(Q0 Q1 Q2). Let's say, initially, the output is at Q2; the light would be off. If the button is pressed once the output shift to Q0. Q0 basically powers the astable circuit which in turn turns on the blinking mode. Another press would enable the led directly and the light glows normally. This cycle repeats.

Q3 is connected to the reset button of the IC. It restarts the sequence once it passes Q2

Astable circuit: Two transistors are used to produce blinking action. The circuit produces a square wave on the output whose time period can be adjusted by changing the value of capacitance.

Power supply: Since the device needs to be compact I used a lithium battery from an old phone and embedded it inside the cap. A booster module is used to convert 5V to 12V and the led and whole circuit works at 12V.

The clock pulse is given by connecting a switch from the CLK pin to positive terminal of the source.

Before building the circuit I made a simulation to see if the circuit works properly and check the connections.

The two 100k resistors are connected in parallel to produce 50k. You can directly use a 47k resistor. Similarly, the two 47k resistors are connected in parallel, you can use a single 26k resistor. These values are selected from a series of trial and error tests. Changing the resistor increases or decreases the blinking time. Alter the value and find the one that suits you best!

The cap had a folded fabric at the bottom part. So it was easier to hide the electronics. No holes were made to access the switch, it was embedded underneath the fabric. Used some needles to secure the electronics in place.

The cap had plenty of space to hold all these parts. However, a smaller and thinner booster circuit can also be used.

And you are done building the device. It looks really good at night but some may find it cringy. Nevertheless, it was an easy device to make and I look forward to using it for a long time. Cheers!

NB: It is not waterproof. Disconnect the circuit before washing the cap