Friday, December 24, 2010

Wood block LED clock (part 2)

Making wooden enclosure.

Box can be made from any available material i.e. wooden boards, MDF or plywood.

I had some MDF sheets in my scrap container so I've build simple frame from narrow panels of 1/2" MDF.
Before joining pieces together I've applied some carpenter's glue to matching surfaces. Glue fills gaps and add extra strength to joint.

All parts fastened with 1" wooden screws. To avoid material splitting I've drilled 1/8" pilot holes for screws and made countersinks.

Front and back panels are made from 1/4" MDF and attached to frame with glue and screws. Wooden putty can be applied over top of screw heads to make surface even and smooth.

It's a good habit to keep scrap material just in case. 

Wednesday, December 15, 2010

Wood block LED clock (part 1)

Clock controller and LED matrix.

For this project I've picked up few obsolete chips that have been sitting in a drawer for a long time waiting for occasion.

Clock's brain is based on PIC16LF876A microcontroller running at 10MHz.
Basically, only function of microcontroller is to monitor two buttons and occasionally read data from real time clock and display time and date. 

Yes, it's too powerful chip for such a simple application but I prefer to have spare I/O pins and memory room in case I need to upgrade design or add some extra features.

Clock is showing current time by turning ON and OFF predefined number of LEDs of the same color. LED pattern is chosen randomly and microcontroller generates new LED pattern every second.   
If button 1 is pressed clock shows current day and month in the same manner for a 30 seconds then switches back to time showing mode. Button 2 is used to activate time or date setting mode.

Real time clock is NJU6355 chip with 4-line serial interface and operating voltage 2 - 5V.
RTC is bundled with 32768 Hz watch crystal and 3V lithium coin cell battery CR 2032 as a backup power source. Battery is connected in series with diode and supplies 3V to RTC only when main power 5V is absent.

Controller assembled on a single sided PCB, made using heat toner transfer method, as usual;-)

Thursday, December 2, 2010

Wood block LED clock (intro)

Wood block clock. I've seen it. I liked it. I've made my own. 

Yes, I like to work with wood and I like to experiment with microcontrollers and other electronic stuff so I've combined few popular ideas and recreated this exotic LED clock encapsulated in chunk of wood.
Wooden block clock showing time 18:36.
Yes, there are no digits displayed. Instead lights of different color represent ones and tens of minutes and hours.

Sunday, November 28, 2010

DIY hard drive clock (part 12)

Hard drive clock. Final part.

Well, unit is pretty much completed. Hard drive platters are humming a little bit but I wouldn't consider it as significant flaw. Overall it's a very impressive gadget and it shows time as well.

As final visual touch I placed blue power LED indicator behind front panel grid.
Front panel's custom label is made using heat toner transfer technology. It works the same way as for PCB fabrication.
For protection aluminum panel is covered with matte acrylic lacquer.

DIY hard drive clock (part 11)

Hard drive clock cover.

Old cover for hard drive case had to be modified to suit new purpose of reworked device.

4" diameter clock window is manually cut in cover.
Although cover is made from light and relatively soft alloy but it was too tough for manual nibbler so I had to drill series of 1/8" holes along circle then rip out round window and finally smooth edges with file. 

Whole cover repainted flat black and covered with transparent acrylic lacquer for additional protection.  

Illuminated clock dial is attached to cover with hot glue.  

Thursday, November 25, 2010

DIY hard drive clock (part 10)

Illuminated clock dial.

Main purpose of clock dial is to seal hole and keep dust away from sensitive mechanical parts.

At first it was intended to be just a dust cover but, since whole device resembles a mechanical clock, I've added simplified hour marks to it.  

Hour marks are milled using drill press converted into manual mill by adding x-y table.
Edge-lit technology applied to acrylic dial make it much more attractive (well, next model may include second edge-lit acrylic layer with engraved digits).

Dial is illuminated by 4 high intensity blue 3mm LEDs embedded into its sides.
Each LED is inserted into short slot and secured with hot glue.
All four LEDs are wired in series with resistor and connected to 12V circuit.
To achieve comfortable soft brightness, LEDs current is limited to 5mA by 470 Ohm resistor.

Friday, November 19, 2010

DIY hard drive clock (part 9)

Front panel assembly.

Front panel consist of two pieces: plastic support panel and aluminum faceplate separated by wooden spacers.

Support panel is cut from plastic cover of old printer. Panel holds controller board and illuminated control buttons board.

Faceplate is made from scrap aluminum and fastened to support panel with machine screws. 

To keep various power cables and control wires in order improvised wire holders made from 1/4" PVC drain tubing are used. Holders are attached to panel and chassis with hot glue.

Thursday, November 18, 2010

DIY hard drive clock (part 8)

Visual enhancement.

This step may be considered as optional but it increases contrast of image being generated and improves overall visual appearance.

Light emitting part of hard drive is completely shielded by custom made cover.
Ambient reflected light and unwanted color glare are blocked by cover so light that can be seen by observer is coming only through slot cut in platter.

Cover for hard drive is made from plastic case of old printer, combined with part of food container .
Parts of cover are hotglued together and painted flat black.

Saturday, November 13, 2010

DIY hard drive clock (part 7)

Assembling unit

For easy maintenance all electrical interconnections between assemblies are implemented with flexible cables and connectors.
To center hard drive on a chassis I had to reposition existing power supply board. 

To lover noise and vibration to minimal level I reused rubber shock absorbers from old computer. Shock absorbers are mounted on custom brackets and fastened to hard drive frame.

Four machine screws are installed onto chassis to serve as mounting posts for shock absorbers.

Monday, October 25, 2010

DIY hard drive clock (part 6)

Illuminated push buttons.

Here's another simple micro DIY tutorial: LED and tactile switches are combined into illuminated push button.

Buttons are mounted on a small home-made PCB.
Two buttons electrically connected in parallel and resemble momentary switch.
LED is sitting on top of buttons and transmits force to switches when pressed.
Spring shaped leads are soldered to the board.
LED motion is relatively short so it shouldn't affect integrity of electrical connection.

Buttons and LEDs are connected to digital port of microcontroller and can be controlled independently.

Monday, October 11, 2010

DIY hard drive clock (part 5)

PIC18F2320 based controller for hard drive clock.

Hard drive clock is powered by Microchip PIC18F2320 clocked at 40MHz.
PIC18F2320 is a fast and versatile microcontroller with hardware I2C serial interface and plenty of I/O ports to handle communication with all external modules.

Actually, any medium range microcontroller can be adapted for this project. I have quite a collection of various PIC microcontrollers and I've chosen chip with excess of memory and I/O ports to allow some modification in the future.      

PIC18F2320 based clock controller.

Sunday, October 10, 2010

DIY hard drive clock (part 4)

Real time clock DS1307.

Excellent compact SMT design intended for embedded applications, made by Sparkfun.
This tiny assembly contains I2C compatible RTC chip DS1307, clock crystal, back up lithium coin cell  (CR1225 41mAh) battery and 5-pin connector.

I2C interface allows easy integration into any microcontroller based design.

Fresh battery should provide enough energy to support time keeping capability for very long time without external 5V power. According to Sparkfun, up to 9 years.
Well, I cannot wait such a long term to prove it so I take it as is;-) 

Real time clock DS1307.

(part 3)<--- DIY hard drive clock ---> (part 5)

DIY hard drive clock (part 3)

Index sensor

Purpose of  index sensor is to detect beginning of disk revolution to synchronize image being generated.
There are many kinds of remote sensors with identical logic output which are suitable for this task. The only difference between them is how sensors  interact with indexing disk.
- IR photo interrupters. Require cut slot or hole in disk.
- IR photoreflective sensors. Require high contrast mark (black line on a white background) placed on a disc surface.
- Hall effect sensor or reed switch. Require magnet attached to disk.

I've searched through my parts cabinet and found among my stock few SS49E analog Hall sensors.
Output  of SS49 is proportional to the strength of the magnetic field.
Normally  output is 2.5V but it rise up to 5V or drop to 0V when sensor is facing corresponding pole of a magnet.

Friday, October 8, 2010

DIY hard drive clock (part 2)

RGB LED light installation.

Any type of LED light can be employed for this clock design but since my discovery of affordable flexible RGB LED strip I use it in most of my LED based projects.
LED strip has self-adhesive backing and consists of easily separated sections and intended for 12V operation.
Every section contains 3 RGB LEDs with common anode, SMT current limiting resistors and soldering pads on each end.

Electrically all sections in the strip are connected in parallel so whole LED strip can be powered by connecting supply cable to any section. 

Flexible RGB LED strip and more rigid plastic base.

Tuesday, October 5, 2010

DIY hard drive clock (part 1)

Hard drive dissected.

Now it's time to take hard drive apart and see what we can reuse.
My victim is SCSI Fujitsu brand with spindle speed 4400 RPM. Full disk revolution takes 13.64 mSec.

Hard drive. Open and eager to get new guts. 

Some parts definitely can be reclaimed for other projects.
Voice coil actuator; can be used as laser beam shutter or as simple galvo. 
Couple very strong neodymium magnets; those may be used in solar pendulum  toy.
Hard drive platter itself is highly reflective and can be used as front surface mirrors for laser spirograph project.

Wednesday, September 29, 2010

DIY hard drive clock (intro)

Hard drive clock. New life for old junk.

Technical idea is pretty old but making things is fun and hard drive clock itself is very cool and entertaining device.
It's quite easy to build one and I'm sure that most  DIY-makers have some unwanted PC hardware that can be easily put into service again.

Obsolete hard drives. Are they good for something?
Beside hard drive itself, for this project we need microcontroller, real time clock, photo interrupter or Hall effect sensor and bunch of RGB LEDs. All this stuff is widely available. 

Wednesday, September 22, 2010

DIY laser spirograph (part 7)

PIC18F1320 based controller for laser spirograph. Final release. Ready for order.

Well, I think, prototyping stage for laser spirograph project is over and it's time to release final design for DIY community.
For final controller I've ordered factory-made double sided PCB with lovely green solder mask (people always wonder why my home-made PCBs are not green ;-))

PCB fabricated by Futurlec

PCBs are made by Futurlec. It's my first order from this Thailand based company and I'm quite happy with quality of work and service. Lead time is about one week. There's no minimum order but price is really good if to order in quantity.

Along with Gerber file format they accept files from most PCB CAD software like Altium, Eagle, Orcad, Protel. Within days they send back images of processed PCB layers for confirmation and correction (if needed) and within week manufacture PCBs.
And yes, they sell parts too ;-)

Sunday, September 19, 2010

DIY laser spirograph (part 6)

Improved SMT version of PIC18F1320 based controller for laser spirograph.

Controller board is completely redesigned and tightly populated with SMT components.

MIC4680 based switching voltage regulator eliminates needs for bulky aluminum heatsink.
As result controller has significantly shrunk in size and now it can be used as a base for true pocket laser show projector. 
Controller's retained embedded voltage regulator to supply power for low power laser module within 2 - 4V. Regulator's built around SMT LM1117 chip and incorporates dedicated open area of PCB as a heatsink.
Controller supports 5V and 12V fans. Fan voltage is set by wire jumpers on board.

Controller v2 for laser spirograph. Final design.

Along with auto and manual modes of operation modified controller's acquired new exciting feature.
It's ability to store your favorite patterns in internal memory with just press of a button and replay them as a slide show.
Up to 80 patterns can be stored and replayed as endless sequence. Time of displaying single pattern is adjustable and can vary from 3 to 60 seconds. Also there's manual step mode when next pattern in sequence is triggered by a button.

Monday, September 6, 2010

DIY laser spirograph (part 5)

Final steps. Enclosure.

Voltage regulators require individual heatsinks!!!. Metal tab of LM7805 is connected to ground but in LM317 metal tab is connected to output terminal therefore common heatsink for both regulators is strictly unacceptable.

Heatsinks can be easily fabricated from available light gauge metal.
Couple custom shaped  pieces of scrap aluminum will do the trick.
Use of thermal compound is preferable.

Friday, September 3, 2010

DIY laser spirograph (part 4)

How to build spirograph controller from a kit. Step by step assembling guide.

NOTE!!! Given information is provided for visual reference and may not reflect latest design changes and modification but every ordered kit supplied with updated schematic and component map. 

Kit includes PCB, preprogrammed with latest firmware microcontroller PIC18F1320 and all electronic components to build controller for advanced laser spirograph.

Complete part list:
1 x Capacitor 100nF          
1 x Pol Capacitor 100uF      
2 x Pol Capacitor 10uF          
1 x Diode 1N4148           
3 x 2N7000 MOSFET           
2 x Resistor 10K          
4 x Resistor 330R            
3 x Potentiometer 10K          
1 x Resistor 10R          
1 x Resistor 240R          
1 x Potentiometer 1K          
1 x SPDT Toggle Switch       
1 x preprogrammed microcontroller PIC18F1320    
1 x MC78M05ACT Voltage Regulator   
1 x LM317BT Adj Voltage Regulator   
1 x DIP-18 socket           
1 x ICSP Header, 5-Pin       
1 x PCB                

As electronic device, controller is pretty simple and assembling requires only basic soldering skills and minimum set of tools:

 - multimeter;
 - soldering iron, liquid flux, wire solder;
 - fumes extractor (or work in well ventilated area);
 - tweezers, pliers, wire cutter, small flat screwdriver;
 - 22 AWG stranded wire;
 - alcohol, soft brush;
 - heat shrink tubing;
 - glue gun.

Monday, August 30, 2010

DIY laser spirograph (part 3)

PIC based controller for laser spirograph.

The most advanced and sophisticated laser spirograph can be built only with programmable microcontroller.
Design of my spirograph is based on 8-bit microcontroller PIC18F1320 from Microchip.

PIC microcontroller implements software PWM generator with 3 independent outputs. Each output drives 2N7000 MOSFET (can be replaced with any suitable N-channel transistor with gate threshold voltage <5V). Fan is connected as load for MOSFET.
Device supports 5V and 12V fans with working current up to 200mA. Fan's voltage is selected by jumpers on board.
All  PWM outputs generate signal of the same frequency but duty cycle (0-100%) can be set individually for each output.

DIY laser spirograph (part 2)

Manual motor control.

The simplest and cheapest  way to control speed of DC motor is by using variable resistor connected in series with motor.
This method is applicable to any low power DC motor like 3V pager motor. Direction of rotation is selected by switch.
If you want to use chip cooling fans in your design, keep in mind that it's impossible to reverse cooling fan simply by switching power polarity since fan assembly incorporates electronic driver which is designed to maintain motor speed and direction of rotation.

Motor control. Simplest way.

Thursday, August 5, 2010

DIY laser spirograph (part 1)

Motorized mirror assembly.

Since laser spirograph is not intended to be precise optical instrument, any available reflective material may be used as a mirror.
I know some folks have experimented with regular glass round mirrors, dental mirrors, hard drive plates and built decent working devices.
CD/DVD media may be used as mirror too but because of data tracks CD acts like diffraction grate and splits bright laser beam into few weak beams.

DVD as a mirror. It may work as a temporary solution. 

Sunday, August 1, 2010

DIY laser spirograph (intro)

Simple laser show everyone can build.

DIY laser spirograph.  Cool and affordable laser show.

According to Wikipedia, spirograph is a geometric drawing toy that produces mathematical curves known as hypotrochoids  and epitrochoids.
Yes, it sounds like quite complicated scientific apparatus and, believe me, mathematical equations describing those curves look terrifying too, but it's a wonderful toy so if we leave boring science behind we'll learn that it's quite easy to build one and it's a real fun to play with.

Monday, July 5, 2010

LCD backlight repair

How to repair LCD backlight.

LCD backlight failure is most common cause that gadget ends up its useful life on a scrap yard.
In reality, this problem can be easily fixed by replacing faulty CCFL lamp or (and that is much more interesting) by making new light source using modern super bright LEDs.
DIY LCD backlight repair.

Technique described below can be applied to repair or modify any kind of LCD.


Friday, February 5, 2010

DIY backlight for analog meter.

Another example of successful implementation of a method of making custom backlight that was described in details in previous post.

In this project I added two color backlight with separated control to vintage analog meter.
Blue light serves for improving visibility of dial in the dark and for aesthetic purpose. 
Red light can be used as a warning signal, to indicate that measured value has reached predefined limit.  
Blue and red  LED circuits are powered by two separated 5V sources.  
DIY multicolor backlight for analog meter.

This project is very simple, cheap and novice friendly but may result in quite impressive mod of some piece of obsolete hardware.

Parts and materials used in project:
 - ancient analog voltmeter;
 - 3 mm red and 10 mm blue LEDs;
 - resistors;
 - wires;
 - breadboard;
 - piece of acrylic.

Monday, February 1, 2010

DIY LCD backlight

Simple tutorial how to retrofit old type LCD by adding custom backlight of any color.

The same technique can also be used to repair or modify LCD of any size.
Main idea of this method is to place custom built light emitting panel behind modified LCD glass assembly. 

Source of light are bright 3mm LEDs embedded into edges of panel. It's a simple and very reliable approach. 
LED backlight requires only one low voltage power supply, it doesn't flicker or make noise and brightness can be controlled with PWM.

DIY LCD backlight.

This method doesn't involve use of complicated equipment, just regular set of hand tools, small file, sanding paper of fine grit, soldering iron.

Tuesday, January 12, 2010

DIY Front Surface Mirror

Front surface mirror is essential part of any laser spirograph and scanner but such kind of stuff is not available at hardware store.
After internet search and few trials I've developed method of making FS mirror from acrylic mirror by removing protective layer from back side of mirror. I use combination of paint remover and acetone but those chemicals dissolve acrylic base of mirror so it requires some practice before acceptable result could be achieved.


Since I've discovered Winner Colors Stain Remover I stopped using any other solvents and chemicals.
I highly recommend this product. It's non toxic, environment friendly, water based liquid which will not harm acrylic and your skin. 

Now it's possible to make mirror with perfect surface by following next steps:
1. Pour Winner Colors Stain  Remover into proper container.
2. Drop mirror into container. Painted side up.
3. Let it soak for 10 min or more (time may depend on back paint and size of mirror).
4. If paint got loose and started peeling off, remove mirror and put into container filled with tap water or rinse it under water stream. You may use cotton balls and gently swab mirror while it immersed. Optional step is to rinse mirror with steam distilled water in order to remove any particle left from tap water.
That's it. Let mirror dry and don't touch it with bare fingers.
Yes, one more step. 
5. Pour remaining liquid back into bottle for future use.

Monday, January 4, 2010

Mirror balancing for laser spirograph

Design of my spirograph is based on a regular cooling fans.
Fan is widely available part and it's easy to mount mirror on its flat back side.  After some experiments, I've developed simple and reliable method to mount, adjust and balance acrylic mirror in order to achieve smooth and quiet performance.

All described below is applicable only to plastic/acrylic  mirrors !!!

DIY  spinning mirror for laser spirograph.