Nerdy Gurdy LED help?

Hello, I’m working on building my nerdy gurdy - a DIY hurdy gurdy - and I’m playing with the idea of putting LEDs inside it plus perhaps some on the wheel cover.

I’ve not done anything with LEDs before and if anyone would link me to some guides or wants to recommend specific parts to buy, I would be grateful!

Led’s require current limiting.The simplest method is by a resistor in series with the Led. Multiple ones can be wired up in series if the supply voltage is high enough. Voltage drop Vf varies - the red ones being the lowest at 1.8 to 2.0 volts, followed by green at 2.0 to 2.2 volts, yellow at 2.1 to 2.2 volts. Amber are around 2.0 volts. Highest volt drop are the blue and white Led’s at 3 to 4 volts averaging at 3.4 volts. On hyperbright Led’s the Vf value may differ. Formula for series resistor (Vsupply - VdropLED) ÷ current required in mA. Exchange current required with the closest resistor value to see actual operating current. Operating current used is dependent on supply source with 10mA being a realistic maximum on AA batteries per Led circuit loop. There are low current types but the brightness values are low. I’ding the polarity is fairly easy. The shortest (supplied) lead usually enters the Led case by a flattened portion. This is the cathode lead.
Driver circuits. Simplest is a flashing Led connected in series with the others. A series resistor can be used to make up any difference in the supply voltage. Use of CMOS logic ic’s are fairly simple to understand. Supply voltage is around 15v maximum for the 4000 series. Use a CMOS 555 timer as a clock oscillator. From this you can drive a counter ic. Various types available such as the 4017 Johnson decade counter and various ripple binary counters. One counter, the 4060, has a built in oscillator and upto 14 divider stages for a single chip solution. Use ic sockets to minimize handling of the ic’s during construction as they are static sensitive. A lead straightener tool would be useful here. There are 74HC logic ic’s available but the supply voltage must be limited to 5.5v to 6v absolute maximum. The HCT ic’s are for 5v operation only. There are also microcontroller boards available. Popular small board ones are the Arduino Nano and ATtiny. Higher current output driver circuits vary from a simple transistor wired as an open collector driver to ic’s such as the logic buffers and the ULN Darlington drivers.

Hi @Orion_Dooley. What sort of effect do you have in mind? Do you want plan white, changeable colours or programable LEDs that can do patterns?
I favour 5V LEDs that can run of USB battery packs.
As a example a quick look on amazon you can get something like this.
Or for the more complex approach this is achievable

@Shackbob602 thanks for your reply!

@AndrewPatience I’m planning on making a wheel cover and was considering putting a single string (could be two I guess) on the inside of it to illuminate the wheel.

Were you thinking of having the wheel illumination a single colour, multi colour, multi colour with moving patterns or even having a multi coloured pattern which stays static as the wheel is rotated …? :slight_smile:

Hmm actually I’m going to have to plan this out a bit more. I’m on the finishing stage now… I need to stain, sand, shellac, sand, shellac, sand, varnish, sand, varnish, sand sand sand!

Then I very much hope it holds the tension in the strings… I’ll be very sad if it dies afar all that!

Once you have a microcontroller and RGB led string you have quite a lot of flexibility over the exact implementation you arrive at, you can experiment with different effects at will.

How did the eternal varnishing and sanding go ? :slight_smile: