Posts

Showing posts from November, 2013

TP-LINK TL-WR740N WiFi Router Here's how to: Flash a TP-LINK TL-WR740N WiFi router with OpenWRT  ( Wikipedia ) Install toolchain which will run on your x86 Ubuntu computer but compile for  the MIPS processor (Atheros AR9330) present inside the TP-LINK TL-WR740N. Cross-compile a hello world C program on x86. Transfer the executable to the router and run it. Flashing the router with OpenWRT Figuring out the model number Look on the back side of the router and figure out your model number Mine was V4.23 . I looked up the corresponding entry for that model on the OpenWRT's Wiki Page for TL-WR740N here  http://wiki.openwrt.org/toh/tp-link/tl-wr740n  under the "Specific Install Notes" section and read: "Hardware version 4.23 works perfectly with the unmodified Attitude Adjustment (12.09-beta) generic WR740N v4 image . The best installation method is flashing it through the stock TP-Link web interface." So I clicked on the image lin

Measuring the hot resistance and cold resistance of Incandescent Bulbs

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 resistance, y