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Sunday, May 27, 2012

Sunday, May 20, 2012

R-2R DAC / Arduino signal generator + DIY Oscilloscope

Arduino and R-2R DAC working as a signal generator. Check this link for detailed info. I went a different way with the coding inorder to add a delay function between individual pulses and not cycles so i could influence the frequency. The code is big and it took sometime to write but it worth it not only for the delay but for the resolution too. Here you can download my Arduino sketch (R_2R_DAC). The DIY Arduino GLCD Oscilloscope by
Important note: I use the digital pins (3-10) and the sketch works only for these pins because i initialized them using DDRD and DDRB


Thursday, May 17, 2012

Friday, May 11, 2012

Zener Diode voltage regulator (Basic Circuit) !

This well known circuit requires one Zener diode. The circuit works as the input voltage increases the current through the Zener increases but the voltage drop remains the same and as a result the voltage drop across the resistance increase (IR.R) in this amount (Vin -Vz)

Using iCircuit App for iPhone

Its important to pay attention to the power rating of the Zener and the Resistor, matching them to the current that need to be delivered to the load.
ex: If the output Load (R-Load) needs 100mA of current then the power rating of the Zener should be 1W at least (100mA x 10V). Similarly with the resistor (R) the power rating should at least equal the voltage drop across the resistor times the current output (5 x 100mA) which gives us 500mW.

Wednesday, May 9, 2012

Temperature monitor and remote control (Server)!

ENC28J60 Ethernet module (3V3 and 250 mA), Arduino MINI, Nokia 5510 Display, Dalas DS19B2 Temperature sensor (connect a pull-up resistor between pin2 (DQ) and pin3(VDD)), LM317L Voltage regulator to obtain 3V3 for the Ethernet module. Note that the ENC28J60 is 5V tolerant but i prefere to go by the book and not destroy it. The LM317L is able to give max of 300mA. (Arduino MINI does not have a 3V3 PIN but UNO and other boards do)

You can easily Download the Arduino Sketch (Temp_CTRL.pde) 
The sketch is based on the examples provided with etherShield and OneWire libraries, 
so feel free to modify the code and post results.