Electronics FAQ

Mobile Phone/Tablet charging Power Banks can be used to power so many DIY projects. But if your project is low power and draws very little current, the power bank will auto turn off after a few seconds thinking that it isn't being used to charge gadget (because the current draw is very low). I need to figure out a way to hack one and locate and replace the current sense resistor with one of a higher value. Here is how I did it. This  told me that the resistor would be located on the return path (ground path) of the output USB connector. I promptly located the R100  SMD resistor in my iBall portable charger. The fact that this resistor was fatter (higher power dissipation rating) and that it was 0.1 ohms in value confirmed that this had to be the current sense resistor Original 0.1 ohms current sense resistor I measured the voltage across it when nothing was connected. It was zero volts and the portable charger turned off in a few seconds when nothing was being charg...

My cousin sister left me an awesome Floor Lamp ( Ikea Orgel Vreten Floor Lamp ). Since, the lamp was bought from USA, I had to modify it by installing alternate holders for the bulbs available here in India. Indian bulbs had different threading. The Floor Lamp Once that was done, I started thinking of ways to neatly install a dimmer for it since I couldn't find Indian equivalent for the American/European ones like this one here . I tried to stick one to the plug - it worked - but looked really ugly: First try Then one day, I remembered to  ask Rohit Garg, if he had a better way of getting this done, and he did. He used an adapter casing and installed a dimmer inside it. He also added a metal knob to make it look even better: Plug in Dimmer made by Rohit I got another brainwave to use the white three core ironing cable to replace the lamp's existing black one to match the white walls. Ironing Cable Floor Lamp with the jugaad dimmer installed As an...

Why do we use 11.0592 MHz with MCS-51 variants? The original 8051 could be operated at a maximum frequency of 12 MHz ( reference ). And 11.0592 MHz was the frequency very near the maximum operating frequency which was still a multiple of the standard baud rates. By the way original 8051s executed a single machine cycle every 12 clocks, so at 12 MHz, the instruction execution frequency was 1 million instructions per second. What are the standard baud rates? Baud rate refers to number of symbols sent through a channel in one second. The standard baud rates are 2400, 4800, 9600, 19200, 38400, 57600, 115200 etc. Baud rate is also known as symbol rate. These are the symbol rates used in all kinds of serial communications. The first serial communications were those that were carried over telephones lines. (Reference: Bell 202 Modem , Acoustic Coupler ) What is the relation between baud rate and bit rate? Baud rate is number of symbols per seconds. Bit rate is number of bits per seconds....

The Bulbs So I took 3 bulbs of 40 Watts, 60 Watts and 100 Watts respectively and measured the hot and cold resistances I used the Philips softtone frosted lamp series. Price: 40 Watts : Rs 20 60 Watts : Rs 20 100 Watts  : Rs 21 Blub packs - Front Blub packs - Back Cold Resistances The cold resistance readings were as follows: 40 Watts : around 97.6 Ohms 60 Watts : around 71.4 Ohms 100 Watts : around 39.5 Ohms Measuring Cold resistance of 40W Bulb Measuring Cold resistance of 60W Bulb Measuring Cold resistance of 100W Bulb Hot Resistances (Calculated) Calculated values of hot resistance can be obtained using the formula: Resistance = (Voltage^2) / Power In India the AC voltage RMS value is 230 Volts. So we get the hot resistances as: 40W Bulb : (230*230) / 40 = 1322.5 Ohms 60W Bulb : (230*230) / 60 = 881.67 Ohms 100W Bulb : (230*230) / 100 = 529 Ohms Hot Resistances (Measured) To get the actual values of the hot resistanc...

This is an old post from Bunnie's blog, but makes a fascinating read. Welcome to the world of counterfeit electronic components!  http://www.bunniestudios.com/blog/?p=918  

BC547 is a general purpose NPN Transistor (datasheet here ) which us very popular among hobbyist and engineers alike. But why is it so named? The naming or more specifically “numbering” of most transistors can follow any of the three systems: 1. Pro-Electron (European) 2. Joint Electron Device Engineering Council (JEDEC) 3. Japanese Industrial Standard (JIS) BC547 is a name registered under the Pro-Electron numbering system. The Pro Electron system is the European type designation and registration system for active components, such as electronic tubes and cathode ray tubes, semiconductors, liquid crystal displays, sensor devices, etc. providing concise and unambiguous type designations. The system provides integrity of the designations, and creates transparent and unique product identification, thus preventing confusion in the market place. All Pro Electron type numbers consist of a prefix followed by a serial number. The prefix, generally two or three letters, cl...

I am an electronics engineer and I live in Mumbai. Atleast I used to, until I shifted to Pune, but since my parents live there, I visit Mumbai very often. Of the major cities I have been to - Mumbai, Delhi, Bengaluru, Chennai, Pune - I find Pune's climate among the most pleasant of them all. Bengaluru's would have been comparable had it not been for the pollution. Mumbai (and Chennai's) humidity levels are always unbearable to humans as well as machines. No matter how well you design a machine, it will always die out a lot earlier in Mumbai as compared to its exact same counterpart put to use in a dry city like Pune. No wonder cars used in Mumbai have a lesser resale value - who wants a second hand car which has been tortured by humidity for many years! I am a fan of mechanisms. The word mechanism has two definitions: A system of parts working together in a machine; a piece of machinery. A natural or established process by which something takes place or is brough...

A Tutorial on various kind of Piezoelectric transducers from Open Music Labs: http://www.openmusiclabs.com/learning/sensors/piezos/

'Coz I keep forgetting the directions of the RS232 signals all the time.

Electroluminescent strips are available in all shapes and sizes. They can even be cut to whatever shape is required as long as the end terminals are left unscathed. These strips find use as backlight for watches and other devices having LCDs. High voltage AC signal is required to turn on an EL Display and special drivers are available to achieve this. Typical AC voltages applied to the EL display are 50V to 250 VPK-PK, with a frequency of 50Hz to 1KHz. The current consumption depends on the area of the display - a display having an area of a few (< 5) square inches would draw somewhere around few tens of (< 100) microamperes. So the job of the driver is to essentially draw a few tens of milliamperes at 3.3/5.0 volts DC and convert it to around 100Vp-p AC at a few hundred hertz and supplying a few tens of microamperes of current. Information Regarding ELs: History LuminousFilm EL Wire FAQ EL Driver ICs from Micrel ( Application Note ) EL Driver ICs from Supertex Dr...