Hobby Projects - Insulation tester, LED Circuits, Meters.

Wednesday, October 20, 2010

Professor Mark Csele - Projects and Hobbies

"I present, below, a collection of projects I have worked-on over the past few years. For over a decade, I had taught both embedded systems (microcontroller technology) and digital signal processing and practice what I preach...."

Professor Mark Csele - Projects and Hobbies

Nixie Thermostat - A heating and cooling thermostat employing technologies spanning fourty years from the unique Nixie tube display, circa 1960's, to a PIC 18F microcontroller, circa 2006.

A High-Powered Power Backup Inverter

A High-Powered Power Backup Inverter - The working prototype of the 2 KVA inverter is complete. Fed from an array of lead-acid cells totalling 600 Ah (at 12 Volts), it easily drives real-world loads such as single-phase motors. The inverter has been tested and found to operate at an efficiency of between 71% and 82% driving a variety of both inductive and resistive loads

LED Lamp or Bulb with Flashlight option

This is another LED lamp from China, these people make nice lamps and also good designs of the plastic enclosure. Here by a clever enclosure design it is both a emergency mains bulb and Torch/Flashlight.

The price is low and they use a small sealed lead-acid battery worth 4.5 V and around 1 AHr. That means it could give an hour of performance at 1 A drain/usage. The voltage by the elapsed hour could be near 4. Here the battery failed, vibration or leakage; OR combination of both. The acid, very little or even corrosive vapor has eaten the copper wire of positive wire/junction. The Cut Red wire, broke circuit equilibrium and burnt the R? = 3.3K - 4.7k ?. The lamp failed all other parts intact.

LED Lamp or Bulb with Flashlight option

How it works ?

It uses a step-down cap, this is very tricky. It has to be a HV cap overrated and excellent quality. These caps not good enough. I am partially responsible for this cap idea spreading around. It was decades ago in relation to bringing down the cost of industrial. automation timers. The transformer had to go and smps solution too much; a resistor inefficient. I was triggered by the choke used in tubelights to bring down voltage after firing. So if L can be used, then even C for low currents, no heat wasted. The timer worked, successful sales. Idea/Concept became popular. This idea also misused by others to save cost. This design needs an Axial Polycarbonate/Polypropylene 630V/1KV cap for reliable operation.

Now this 18 LED array, has no current limit, is it not quite a problem. The chinese are innovative on saving cost, here its fine, but.many times we can sacrifice quality. In this design the LEDs drop around 3.3V and the Transistor 1 Volt as it is not driven to saturation. On full load the battery also deregulates, so it does manage to save itself. This transistor also serves as a mains detector along with the 1N4148. On mains failure the LED lamp turns on Automatically.

Another Lamp had a Burst out 100uF cap this means, surges or spikes are damaging the 1uF 400V Plastic cap used for current limit.

Recommendations to such Lamp Designers

Use Metalized Polypropylene MPP - rated for 440V AC continuous working. That means it must be rated like a Power Factor correction/saving capacitor. It may mean 1KV DC operation.
  • Use an Axial 1uF polypropylene 630V DC or 440V AC Capacitor
  • Sell it with a Marketing Advantage as Power Factor Compensation.
  • Use two 2.2uF 630V DC Axial MPP, one on Live and the other on Neutral.
A house using Motors and Fans will have inductive elements, even tubelights that have chokes 50/60 Hz kind. This is compensated by capacitive loads. So each of these Capacitor LED lamps can be a Green Lighting and PF compensator.

Perpetual Candle - White LED Lamp on Ni-Cd

This is a easy to build LED lamp circuit for Learning and building skills. This is the first draft schematic V 1.0. It will need improvements for Higher Power Lighting.

From Schematics of delabs

I will give a short summary, The LM317 here configured for around 6.4V DC. The Q3 BC547 limits the current, you can select R3 to suit, make it 1/2W. The Ni-Cd battery pack 1.2 * 4 will not get Over-Current or Over-Voltage due to this circuit.

The IRF540 Mosfet or any other equivalent you have around, along with Q2 BC547 forms a current source for the parallel 12 LED array. Ultra-bright White LED at 20mA each or use a 1W ready LED Chip. R4/R6 can be selected for the Max LED current. The voltage of LED is around 3.1 and 20mA * 12 = 240mA is the max current. You can Tweak the design for even 5A or more but then you will need a DC/DC High frequency converter in place of LM317. The Current source also needs to switch to improve efficiency. A PWM on the mosfet gives brightness control. The entire solution (switching) can be found in many chips with semiconductor vendors today.

From Hobby Hound - DIY Electronics

One Single High Current LED may work well. 12 Matched LEDs also can be used. In LED Array some are dim, put min. resistor (3.9 ohm) for all 12 for current sharing. The resistor addition will impar the ability of Candle to work at lower battery voltages. Also resistor is less green, It wastes power, so use PWM and Single Die high current LED. Ni-Cd system may last over 5 Years if Candle is allways on Mains. Sealed Lead Acid system may go upto 2-3 years life but will have more punch. A SuperCap system may last more than 12 Years, i feel.

Source in Cadsoft Eagle format - candle.zip

Wednesday, October 13, 2010

Proto-PIC - Prototyping for Hobbyists

eShop and How-To Videos for anyone who has an interest in Microcontroller Programming & Development. Components and Kits for the Electronics Enthusiast.

Orangutan SV-328 Robot Controller

Proto-PIC - Prototyping for Hobbyists

A site designed for electronics and prototyping hobbyists and enthusiasts. This site has grown and is now a useful knowledge base and online shop for anyone who has an interest in Microcontroller Programming & Development or for anyone who has a love of electronics.

Kits and Tools

The Orangutan SV-328 is based on Atmel's mega328 AVR microcontroller, which runs at 20 MHz and features 32 Kbytes of flash program memory, 2 Kbytes of SRAM, and 1024 bytes of EEPROM

Eight general-purpose I/O lines with up to eight analog input channels allow for adding sensors or expanding the system.

Orangutan SV-328 Robot Controller

DSO Nano v2 is a Digital Storage Oscilloscope designed for basic electronic engineering tasks. Within its smart shell, the device runs on ARM Cortex™-M3 32 bit platform, provides basic waveform monitoring with extensive functions.

DSO Nano v2 is a Digital Storage Oscilloscope


  • Portable and lightweight
  • Waveform storage and playback
  • 6 triggering mode
  • 1Mhz Analog Bandwidth
  • Complete measurement markers and signal characteristic
  • Built-in Signal Generator

DSO Nano V2 - Pocket-Sized Digital Oscilloscope