LAKE CITY SPECIAL

Greetings to all,

Lake city special RX (7085KHz) comes with few modifications in the GR40 RX. VXO works @12MHz, BFO and IF filters works @ 4.915MHz. i.e (12MHZ-4.915MHz=7.085MHz).
The block diagram and schematic are given:

Bootloading/Burning hex file to Atmega328 using Parallel port

Dear all,

While working using arduino, Bootloader has crashed, we came with the solution for bootloading/burning hex file into Atmega328 without arduino using icsp pins in microcontroller and parallel port. we have taken the circuit and explanation from avrprogrammers.com.

Here is a solution for Bootloading/programming Atmel atmega328 uisng ICSP pins.

Connect the atmega328 pins(MOSI, MISO, SCK, RESET and GND) as shown in schematic, power up the circuit with five volts. To do this I have used the ISP Programmer 1.2.0.56.
For software click here.

Here is the procedure for using this software:-

VXO

Dear all,

We wanted to make a simple solution for Lake City Net operating at 7085KHz daily between 8:15Am and 8:30Am. We have chosen IF as 4915KHz for which standard low cost crystals are available. This requires a LO of RF+IF=12MHz, We have happily configured a 12MHz VXO. This VXO fortunately covers 11995KHz also giving rise to coverage of CHARMINAR NET operated at 7080KHz daily until 8Am. Below is picture of experimental VXO and the table contains test result.

Different values of the crystal with different capacitor in X position

BATTERY BOOSTER TESTING

Dear all,

Test setup of Battery booster is in the below figure:

This battery Booster is designed for 20A and claims for 10A. We tested it upto 5A.

ALCOHOL SENSOR USING PIC16F887

Dear all,

As a College project we  made an Alcohol sensing micro controller using PIC16f887and MQ3 sensor. When it sense the alcohol the buzzer will turn ON.

SOLAR USB CHARGER

Dear all,

We have made a Solar USB charger for science exhibition in one of the Bsc college,

20*4 LCD

Dear all,

We have done 20*4 LCD being driven by Arduino for one of the Bsc College project for science fair.

. 

MPPT CHARGE CONTROLLER

Dear all,

Here we are with Arduino based MPPT charge controller.This project is inspired from Mr. Tim Nolan’s Arduino MPPT. We can share this as long as we mention his website link.

Here is the link:  Click here

The display part is taken from the KIBI: Click here
We didn’t use Tim Nolan’s hardware as we wanted to be different and simple (No MAX IC’s).

Our circuit diagram is given below:

We tried to make the circuit using IRF5210 because of high input capacitance we shifted to IRF9540. We used instrumentation amplifier TL082 to amplify the solar current. To generate –ve voltage required for TL082 we used 555timer and lm7905 for -5volts generation Modification in the software:

We modified the code so that PWM is around 20 KHz and our MOSFET’s are happy at this lower speed.

For your reference this is the link for Mr. Tim Nolan’s circuit:

Click here

DC DC CONVERTER FIELD TEST

We have tested the DC DC converter in field yesterday in SALEM. The two units are working more satisfactorily than we expected. We connected two solar panels of 100Watt in series to get the 40Volts on no-load and 36Volts on load (Battery). The test is continued till the shade falls on the panels at 5:30. For 2hrs the battery gets fully charged.

Improvements in the 2^nd unit:-

There was a high frequency humming sound in the transformer. To reduce that we increased the turns ratio from 7:5 to 8:6. We added two high voltage capacitors (1000uF & 0.1uF) at the input to remove spikes. We relocated the diode to improve the heat dissipation. The MOSFET and Diodes are placed in the front and back panel respectively. The raise in temperature of panels is less than the previous unit.

The pictures of 2^nd unit are given below.

The schematic diagram is shown below.

For more details please feel free to contact us.

BATTERY BOOSTER

This project was originally published in November 2004 QST. We have made the simplified version as shown in the below schematic.

Performance verified at 5A continuous load current to prove the design. For further details feel free to contact us.