by Ramsey Electronics
Traditional strobe light circuits typically use Xenon bulbs which have a short life-span, are expensive and require dangerous high-voltages. In recent years, super bright LEDs have become cheaper and brighter, making them affordable for everything from traffic signals to vehicle tail lights and strobe circuits. You can use high power LEDs for the same effect and get a nice bright blue flash without the high voltage, and no glass tube to break.
The kit comes with a 9 LED array, but a 20 LED array is also available. The LEDs will last virtually forever instead of burning out after a short time like an old Xenon tube.
As well as flashing at an adjustable rate like traditional strobe lights, this kit also has an audio input that allows it to flash to music. The high and low pass filters allow the LEDs to flash to treble or bass. There is also an external trigger jack that allows you to control the LEDs with your own external source or connect two kits together.
The adjustable frequency is generated by the LM555 timer IC. The pulses from the IC are fed to a power MOSFET that switches all the LEDs. A power MOSFET is used because it makes a good high-current switch and it won't get hot.
The high-pass and low-pass filter is designed with LM324 quad op-amp IC and its support components. You can select which filter the audio passes through by pushing a switch. After being filtered, the audio signal is amplified slightly by the same IC. After this the amplified audio goes to an NE555 timer, configured as a retriggerable monostable multivibrator. The circuit produces an output pulse every time the audio signal gets above its threshold level.