More on the Pilot Solar Power Setup

The panels are not secured and simply  laid down flat on top of the roof.  Good thing that the roof inclination is not very steep and no chance for the panels to slide down.  I hope to attach them to railings before the typhoon season.  I don't like the idea of putting them on the roof to be honest.  I think I'm putting some stress on the roof and wood trusses underneath when I am up there working on the panels.

I was not using MC4 connectors in the pilot setup.  What I did was to bend some of the strands of the #12 AWG wire enough to make contact with connectors that came with the panels.  To secure the connection and as crude weather seal, I wrapped them with electrical tape. One pair of wire for each panel, therefore I've got 4 wires going down from the roof.

The PWM charge controller has three pair of terminals.  One pair each for the PV, battery and load.  Wires or cables are inserted on slots on one side of the controller.  Inside the slots are metals to clamp to wires when the screws on top of the controller are tightened.  The two #12awg from the PV fits nicely on those slots but making it three could be a challenge.  As for the battery connection I used the common automotive two terminal connector as in the picture.  I defined the terminal near the lock tab as the positive and used female one for all my batteries.  This means the connector from the controller is a male.  Nothing is connected on the load terminal of the controller on my initial setup.

The inverter is directly connected to the battery using the  thick wires that came with it.  Just plug and play as the wires has eye terminals on both ends and colored red and black.  On the AC side, I made an extension with plugs on both ends.  One side plugs into the AC output of the inverter while the other end plugs into one of those wall sockets inside the house.  The next step is to open the breaker box to turn ON the house circuits the I want to be powered up.

Parts List
     2x     100W solar panels
     1x     30A PWM charge controller
     1x     100Ah deep cycle battery
     1x     1000W pure sine wave inverter
     4x     5m #12 awg

Calculated (sunny day) capacity = 200 * 0.5 * 6hrs = 600Whr
Calculated battery capacity = 100 * 50%DOD = 50Ah or 600Whr @ 12V


Total cost ~ 18,000 Php

Log Periodic Antenna (2)

Part 2 (2011)

The objective actually was to have Channel 5 watchable since I am quite certain that Channel 2 and Channel 7 would still be clear even if I screw up with the antenna construction. I believe they have stronger transmission power compared to the other channels and besides, we still have the relayed channels which is very near (about 20-30 kms.) Unfortunately though, the towers are in the opposite direction ( south )


Continued in 2012

Today is May 21, 2012 and I can't remember when I wrote the above paragraph. Obviously, it has been a long time. In the spirit of trying to finish all unfinished posts, I'm gonna write the continuation today without pictures. Later on, I'm planning to review everything.

After several typhoons, the antenna is in a very bad state. Instead of being parallel to the ground, the front points downward. The channels from Manila are all gone suggesting a disconnect somewhere. We can only watch the relayed channels but even if the transmissions tower are nearer, the reception is still not good.

May 20, 2012, I got up early to fix the antenna. It is better to do this in the morning while it is not too hot. Rainy weather is coming and there's rain usually in the the afternoon.

I used magnet wire to connect the element for the simple reason that is quite easy to route. I know then that it was not proper way because I read somewhere that the thickness of the wire used as link affects the overall gain. The magnet wire was replaced with steel cable.

While removing the outer cover of the coaxial cable, I noticed that the insulator broke. About 0.25cm of plastic has separated itself from the rest. It seems like the insulator became brittle over time. I proceeded anyway and connected the cable to the antenna.

I pointed it North (Manila). Now the antenna is back in business with very clear receptions for stronger channels 2 and 7. Channels 4, 9, 11 are watchable although a bit noisy. There were also some UHF channels. But channel 5 which is why started this project is still a letdown with streaks that seem to flow from top to bottom. I wonder if it is caused by a mismatch or simply because the signal is just too weak.

Unable to fix the problem using the TVs fine tuning, I tried to find the optimum direction to point the antenna's front end. I used the coconut tree as the reference but I guess the tolerance is wide. The problem didn't go away. I was now beginning to suspect that something is amiss with the cable..

Fortunately, I have a spare coaxial cable. It is bit shorter compared to the one that is currently installed After making the connections, it is now confirmed that the old cable must be replaced. Channel 5 streaks are now gone and although there is some noise present in the picture which appears as white dots, this is way better and doesn't hurt the eyes as much.

Samsung Galaxy Y Charger Hack

My old and trusty Magellan GPS is due for retirement.  The rubberized cover is now starting to peel off.  One-third of the LCD display is busted due to a fall while travelling at about 80kph.  I used it mainly for tracking back my traveled path and also as an alternative speedometer..etc.  It is really a bare unit with only the basic map installed.  I just used my imagination to make the most out of the gadget.

Recently, I was given this Android phone called Samsung Y with built in GPS.  And so now, the Samsung Y can now replace the old Magellan.

There's a problem though.  When the GPS sensor is ON, and off course some navigation applications need to be active as well, the phone battery lasts only for some hours.  The logical step therefore is to find a way to extend battery life or have a charger always connected.  The phone charges via USB, by the way

I bought a CDR King 12V to USB charger for less than 100php (for those residing outside the Philippines, CDR King is a well-known shop selling electronics and computer stuffs.)  Sure, it charges the phone but only when it is OFF.  Once the phone is turned on, charging stops.  This is unacceptable.  How can I use the phone's GPS function if it is turned off?

Some hacking will be required.  Before proceeding, please read my warning below.

DISCLAIMER :  IF YOU DECIDE TO REPLICATE THIS MODIFICATION, I WON'T BE LIABLE TO ANY DAMAGE THAT IT MIGHT CAUSE.  DO THIS AT YOUR OWN RISK.

After opening the casing of the charger, I noticed that the two middle pins of the USB connector are just floating.  I took a 10k resistor from my parts box and used it to short the two floating pins one by one to either GND or +5V.  The phone still won't charge.

I took another 10k resistor and shorted both floating pins to GND.  The phone beeped and the charging icon came up.
Soldering finalized the hack.

This is the intended application.

It looks like more effort will be needed but at least the phone now charges while it is turned ON!!!

Voltage Stabilizer for Motorcycles

I was lurking in MCP electrical forums and came across with a gadget called voltage stabilizer or VS.

Looking into the schematic, it is nothing but capacitors and wires of course.  A variation is to put a safety feature by inserting a fuse.
Some users claim of better horn performance, easy starting and even fuel economy to mention a few of the benefits.

I tried installing my version of a VS in my motorcycle.  This is how it looks like.  It fits nicely inside the U-box.  Now I have to figure where to put my other stuffs.  Things such as spare tube, wrenches and rain gears.

Unfortunately, I didn't really have the chance to test or gather data to verify the claims above.  I prefer the peace of mind having a spare tube, tools and rain gears.  Perhaps when I can afford to buy a Givi box.

Log Periodic Antenna (1)

The antenna motivation

Who needs an antenna when there's cable TV available?  What is log periodic and why log periodic?

I live about 90 kilometers from the capital Manila and TV signals are weak.  We have two local relayed channels of the biggest TV networks, GMA7 and ABS-CBN2 broadcast on channels 12 and 10, respectively.  A simple dipole is enough to watch these two channels and that was our setup since moving here.  But then there is an emerging power in the Philippine TV network wars and it is Channel 5.  I believe the guys behind this channel is quite aggressive in designing their programming and it is also refreshing to watch an alternative.  I like channel 5 and the kids like it too which is enough reason for me to construct an antenna with a better reception.  To answer the first question, I don't think we need cable TV.  Some news and a little of those documentaries is enough for me.  The kids are happy with Ben 10, Sponge Bob, etc.  Why pay when all of these are available and free?

The log periodic antenna

So what is a log periodic antenna?  The complete name for this type of antenna is Log Periodic Dipole Antenna (LPDA) TV channels are in the so-called VHF and UHF segment of the RF spectrum and each channel has its own transmission frequency.   A dipole antenna can be optimized to receive one channel if cut according to a known formula but it won't be able to give you a good reception when you change the channel.   Since it is quite impractical to cut a dipole for each channel, a log periodic antenna is a good option.  Log periodic are wideband antennas and thus capable of receiving multiple channels.

Why part 2

Since long posts are somewhat boring,  I'll be posting another installment on the same subject.

Calamansi Powered LED

I recently completed a very simple LED circuit powered by calamansi battery.  Yes, you're reading it right, electrical energy from that sour little thing.

Calamansi if I'm not mistaken is translated as Philippine lemon in English.  It is used in cooking, in making sauces or dips, juice for lemonade, medicine for cough, etc.  What I did is a strange application for calamansi.



The circuit is composed of 1 LED (light emitting diode), 1 pushbutton switch, the calamansi battery and wires off course.  Everything is held together either by quick setting glue or solder.  The base used is a piece of illustration board while the small box used to contain some electronic gadgets transferred elsewhere.  When the button is pressed, the LED should light up as shown in the picture.



So how come those calamansi was able to light up the LED?

Normally, a battery has two electrodes, one negative and one positive.  The third element is the electrolyte.  For our battery, I used 1 inch iron nails as negative electrodes and solid copper wire cuts (about 2 inches) as positive electrodes.  Now it should be obvious that  calamansi would serve as our electrolyte.

To create a single cell, a single calamansi gets a nail and copper wire pair pressed into it.  Each cell generates about half a volt which is not enough to light up the LED.  I ended up with 7 cells connected in series.  The LED started to glow with about 5 cells and I added two more to make it brighter.  I don't know how much current this battery can produce but it will not be so much.  That's for sure!

With 7 cells, the open-circuit voltage of the calamansi battery is 3.2V.  It drops when loaded to about 1.6V which is more or less the forward bias voltage for the LED.