Monday, October 18, 2010

1.5V to 5V DC-DC Convertor

I was looking for a simple solution for pumping 1.5 volts to 5 Volts. I have designed various 1.5v- 5V DC-DC Convertors by using special purpose chips. The problem was those chips are very difficult to obtain. Moreover, DC-DC Convertors are mostly required to use coil which is also difficult to get.

Luckily, I found this small breakout board in a local electronics shop (NPE). It was cheap, about USD 10 and small enough to fit in watch case (in the future).
The instruction is very simple, put 1.5 Volt in your will get 5V at the output.

By using this breakout board with my USB battery charger
Attaching this module to my digital wristwatch, then I have a working digital wristwatch. It can be charged via USB. Fully charged batter will make the watch lasts for 10-12 Hours (the display is always on). Now, it needs good case + strap. I have idea but don't have time to continue the project.
I have a plan to disclose the making process and give away the PCBs. But, there are some mistakes in the PCB. The problems can be resolved via firmware. However, I think it's not good to give away the incorrect PCBs. Please wait for the good PCBs and I'll give away some.

Free Circuit Simulator Software

My list of Free Circuit Simulator Software
  • Multisim Free Version
  • Many types of simulators from Linear Technology
    • LTspice IV (Switchercad) is free and powerful. It features all IC chips from Linear Technology. SwitcherCAD™ III is a fully functional Spice III simulator with enhancements and models for easing the simulation of switching regulators. This Spice is a high performance circuit simulator, integrated waveform viewer, which also includes schematic capture. Our enhancements to Spice have made simulating switching regulators extremely fast compared to normal Spice simulators. Included in this download are Spice, Macro Models for 80% of Linear Technology's switching regulators and over 200 op amp models. Furthermore, resistors, transistors and MOSFET models are included as part of this package. With this Spice simulation, viewing of the waveforms of most switching regulators can be achieved in a few minutes on a high performance PC. Also, full circuits using op amps or transistors can easily be simulated.
  • Intusoft ICAP4 Demos : A lot of limitations

Friday, May 21, 2010

DIY LED Watch vs Panerai PAM 127

I have completed a prototype of my LED Watch. I will post the detail about how to make it later. The watch case and strap are missing :)
- Programmable (via ICSP)
- Vintage 7-segment LEDs with slim sigments
- Powered from a coin cell 3.7V Li-ion rechargeable battery
- Built-in USB battery charger

Size comparison between the DIY LED Watch size and a 1 Thai Baht coin.

On my wrist with help of transparent tape :).
DIY Led Watch

The LED Watch prototype is on the left. Panerai PAM 127 or the "Fiddy" is on the right. In case that you are wondering about the strap, it is custom made from a Louis Vuitton bag.
DIY LED Watch, Panerai PAM127

Please comeback and check out for the making of DIY LED Watch later.

Sunday, January 3, 2010

Eagle negative PCB output for printing

To make a PCB by using Dry Film photo resist, I need the PCB layout in negative mode. However, in Eagle PCB design software, I cannot print the PCB design in negative mode directly. After a few searches, I have found a good way to get negative films of my PCB designs from Eagle PCB software and it is very easy. There are  3 steps.

1. Click ‘CAM’ on the menu bar


2. Select ‘PS_INVERTED’ as the output device and then select layers that you want to export


3. Click ‘Process Job’ and it’s done!


The output is ‘yourfile.eps’ which is an encapsulated PostScript. You can use Adobe Illustrator or similar Vector based graphics applications to view/edit/print it.