Charge Controller - Solar to 12V Battery

Welcome back fellow bloggers, readers, well-wishers and mates.

If you have observed, we at RnD have not been posting your findings and projects from the month of April. Why? Well, the RnD team is quite busy researching, destroying and putting our hands into power modules. For the past few days, members of RnD are testing and getting the shock of their life with SMPS amd MOSFET's jumping around the Lab. With a lot of shocking experience in the SMPS technology the team had a lot of charge and enthusiasm to step over to the Charge Controller.

Coming to the Charge Controller, we wanted to build one which can charge a 12V, 100Ah Battery. Why did we want to build a Solar Charge Controller? Sorry but its a Company Secret. Lets just say we want fellow people to utilize the Solar energy that we have in everyone's daily life. It's free and there is not charge or Tax to use Solar Energy (Fingers crossed that no rule will come hopefully).

An adaptation of the The Micro M+ from The ARRL Handbook 2002 edition was built in the RnD Labs. Again, reminder that it is an adaptation and not a copy as the article has a lot of components that is mentioned is American components which may or may not be available in the Bangalore, Indian electronics component market. If anyone would like to read the article, refer any of the ARRL handbooks from 2002 to 2009.

The Charge Controller was first test last week with a power supply (which is not correct/method - but we did not have a Solar Panel). The charging of the battery was fine when the battery was discharged and the charge controller would stop charging when the battery was fully charged. Now for the real test, we requested TATA BP SOLAR to help us out and test the prototype. Their facility has a lot of equipment and were very kind enough to help us. A 80W solar array panel was provided and our charge controller worked beautifully. The battery was a tubular 40Ah battery and the charge controller was cool and was doing the job.

Some of the features of the charge controller:

• The Charge Controller uses a P-Channel MOSFET (IRF9540)
• The Charge Controller runs on the Solar power and hence does not require any additional power supply. Thus, the charge controller will sleep during night time and does not draw any power from the battery
  .

Few pictures of the Charge Controller:

The overall circuit on a single PCB

Front Panel to show the various indications

The back panel which provides the options of connecting the Solar Array panel and Battery to charge.

Here is the schematic of the Charge Controller : Click Here

We shall keep updating the post for more info and finding. Suggestions are most welcome and doubts will be cleared if any.

ISDR worshop at Bharatiya Vidya Bhavan's Muktangan Exploratory Science Centre,Pune, MH

Venue:     Bharatiya Vidya Bhavan's Muktangan Exploratory Science Centre,Pune, MH
Date:       17th May 2012 to 19th May 2012
Kits:        ISDR Kits
Number:  20 Kits


An ISDR workshop was held at Bharatiya Vidya Bhavan's Muktangan Exploratory Science Centre,Pune, MH on the following days: 17th May 2012 to 19th May 2012 with about 20 registered participants. The participants ages varied from the youngest Miss Simran, a 6th Standard student to 77 OM Cyril, VU2AY.

Mr. Vilas Rabde, VU2VPR, took the initiative to conduct this workshop at  Bharatiya Vidya Bhavan's Muktangan Exploratory Science Centre and made all the necessary arrangements in the Electronics Lab to conduct the ISDR workshop. A small inaugural function was held, where the students were given a brief introduction to the ISDR by Abinav C.S. After the inauguration, the students were asked carry to the Electronics Lab to start the workshop.


The first day, the participants were given: 1 ISDR Kit, 1 Soldering Iron, 1 Cable Stripper, 1 Cutter and 1 Screw-driver. A brief  procedure to construct the stereo cable was given and the students started of with a bang to construct the cables. Following, they started on the ISDR Kits. By evening, most of the participants had almost completed the kits.

The second day, most of the participants finished with the kits and were all ready for testing the ISDR. After the D.C. and A.C. testing, the participants followed onto the wiring and in finishing make-up stages.

The third and final day, all the participants finished the ISDR's and were all testing on PC's for stations. In the afternoon, some of the Pune HAM operators were kind enough to come on the band for the participants to have an hands on experience with the ISDR. Thus, the workshop was concluded by evening with all 20 participants successfully completing the ISDR's.

Some eye feasting photos: 

Dr. Ramesh Joshi, Director of BVB's Muktangan Exploratory Science Centre

The participants listening to the introduction of the workshop

Abinav C.S. giving the introduction to ISDR

Participants start the workshop

 

The youngest participant Miss Simran

Participants testing their ISDR on AIR

Abinav helping the participants

VU2UPQ-OM Uday Patil  conducted 40Mtr Antena construction workshop

Participants giving their feedback on the workshop

Certificates being handed over

 

 

PIC Fever

CAUTION: HIGHLY CONTAGIOUS AND NO CURE FOUND YET

Greeting Everyone!!!!!!!!!!!!!!!

That's right - We have got the PIC Fever and its very contagious.

A little history or recap rather of the PIC's we have worked on:

• PIC16F84A  (DATASHEET)
• PIC16F628A (DATASHEET)
• PIC16F887  (DATASHEET)
• PIC18F4520  (DATASHEET)

The last is indeed PIC18F4520, and not a 16F series. The RnD team has moved on to higher series because the work being done does demand higher versions and added features.

Before moving on to the 18F series family, a quick review of what the 16F family offered and a few things common in 16F84a, 16F628A and 16F887:

• 8-BIT Micro-controller
• Operating Speed of 20MHz
• Direct, Indirect and Relative Addressing modes
• Eight-level deep hardware stack
• 35 single-word instructions

All though these maybe some of the similarities which are prominent, we do have additional features in the 16F series.

The programming language is Assembly Level Language and  the program can be ported into different PIC 16F series with little changes. The changes are mentioned in the migration documents available in Microchip site. For instance, migrating from 16F84A to 16F628A is quite simple where you have to just turn-off the comparators in the 16F628A and also change the code-block address to 20H since 16F628A starts at 20H.

Most important is the CONFIG bits in the 16F series, the 16F84A as the least number of configuration bits, 16F628A as a little more due to the added features and then 16F887 has the two line CONFIG definition as then are a lot of features.A small example is, 16F84A has to have a external crystal oscillator, 16F628A has Internal precision 4MHz as well as an option for external and the 16F887 has an internal 8MHz variable and an option for external oscillator.

The list can keep going on for difference's and similarities between the PIC 16F series. So, the question is how do we know which PIC to choose? well, simplest answer is define the project function, read the datasheet, see if the  required feature for the project is available and voila you have a PIC for your project.

The same mantra was followed for another project in the RnD labs and we had to choose another PIC family series for the project. Thus, we stumbles upon the PIC 18F series family. So why did we really choose the 18F, well the project required us to use more stack area and since the 16F series were limited to just 8 levels we moved on to 18 F because it had 31-levels of stack which is far more greater than required.

Small doubt, why no use software stack method? The truth is we are not sure how this is done and there are few sites with great info on this and we are trying out the possibilities of software stack method. Meanwhile, as the current project deadline approaches, we have taken the shortcut and chosen a 18F series to solve the problem.

When it comes to programming the 18F, it is still the Assembly Level Language but the op-codes and style of accessing the Special Function Registers and Access Bank in the 18F is very much different.  Also, the 18F series has an extended Instruction Set with about 75 Instructions. So, with a little change of programming style and datasheet, one can migrate from 16F to 18F quite easily. Also, I have come across that there is not a single place on the internet where a proper migration from 16F to 18F is available. So, we have decided to host a document with necessary changes and migration notes soon enough in our Download Tab.

Stay tunes for more updates. Suggestions and idea will be worshiped in our RnD Labs.