LEDs have always fascinating me. And ever since I first saw Knight Ryder back in the 1980's, I always had a "thing" for LED sequencers. This project originally was designed about 10 years ago, albeit using all thru-hole components, for a rear bicycle helmet light. It was designed to be as bright as possible and super obnoxious - mostly because I was training and commuting a lot on my bicycle in the evening and nighttime hours. I eventually decided to redesign the sequencer with an easier to use operational interface, as well as using all surface mount components. The board is also designed on super flexible 0.031" thick PCB board which can be easily wrapped around curved surfaces, such as the rear of a bicycle helmet.
This LED sequencer has an 8-segment array which can use two or four LEDs per segment, for a total of 16 or 32 LEDs. It operates from a 9V battery, although other battery voltages can be used. With a single 9V battery, the visibility of this thing is ridiculous. Its completely blinding and can be seen miles away! The photos and videos simply do not do it justice as far as brightness goes.
The user interface for this LED sequencer is a single MODE pushbutton. With this pushbutton, the LED sequencer can be enabled and disabled at any time. Patterns can be cycled, and flash speeds can be changed on the fly, no matter which pattern is currently enabled.
Step 1: Features
- (6) User selectable display patterns
- (4) Adjustable flash rates
- PIC microprocessor controlled
- Flash programming connection (so you can program your own code)
- Ultra-High Brightness LEDs - Wide visibility range
- 0.031" Ultra flexible PCB Board - Can be bent around curved surfaces
- Operates from 6-9VDC (other voltages available as well, although current limiting resistors may need to be modified)
- Can utilize red, green, white, or blue LEDs
Step 2: Technical Overview
U1 is a 5V linear regulator. It regulates the input voltage (6-9VDC) to 5VDC which is what is required for the PIC16F505 microcontroller. U2 is the PIC16F505 microcontroller. It is a flash programmable device. The rear of the PCB board features exposed pad terminals for which the customer can utilize to develop their own code for the LED sequencer. U3 is a high current Darlington driver IC. It takes the logic level outputs of the PIC16F505 and provides high current output channels for each of the (8) LED segments. Each LED segment operates at 9VDC with 30-60mA output current depending on current limiting resistors being used. R3-R18 are current limiting resistors which limit the current through the LEDs. Typical LED current is 5-15mA. For this particular design, R3-R18 are 330 ohm resistors.
The PCB board has been designed on a 0.031" FR4 substrate which is extremely flexible. This allows it to be easily bent and formed around curved surfaces such as a bicycle helmet light or curved automobile piece.
- (2) Resistors, 47k, 1206 (R1,R2)
- (16) Resistors, 330 ohm, 1206 (R3-R18)
- (1) Capacitor, 0.1uF, 1206, 50V (C3)
- (2) Capacitors, 1uF, 1206, 50V (C1,C2)
- (1) Linear Regulator, 5V, SOT-23 (U1)
- (1) PIC16F505 (U2)
- (1) TD62083 Darlington Driver IC (U3)
- (32) LED, 3.2x2.4mm, Red (D1-D32)
- (1) PCB Board, Led Sequencer 1.0
- 9V Battery Clip
- 9V Battery
You can download both the .HEX and .C code for this LED Sequencer below. Just note that I am not a good programmer by any stretch of the imagination. I'm sure you could probably make vast improvements on my code here and come up with something even better!
Step 3: Assembly
The assembly is very simple and straightforward. The only thing that could be challenging is if you never soldered SMT components before. Of course, if you etch your own board, you can design it with all thru-hole components.
Be sure to download our PDF manual below!
Be sure to insert the LEDs and ICs with the proper polarity!
Step 4: Performance
Step 5: PCB and Kit
This circuit can be easily built on a breadboard or if your handy, you can also etch your own.
Ordering details for this kit and/or just the PCB board or microcontroller can be found here:
Enjoy and good luck with your project!