Tuesday, December 11, 2007

Lithium Batteries

I’m trying to use rechargeable lithium batteries everywhere I can these days, and I’ve found uses for them in flashlights, motion sensors, radios, portable power sources, wireless keyboards and mice. The trick to using these 4.2-volt batteries in say a 3 or 6 volt application is to make up a dummy battery with a diode connected to the plus and minus ends. The diode provides a voltage drop of just over one volt.

The most common cylindrical lithium battery is the 18500 type, although they can be obtained in AA and AAA sizes.

Using a lithium batteries this way is much better than NiMh batteries as they tend to lose their power over time and their maximum voltage is only about 1.3 volts. I don’t like to use standard alkaline batteries as they often leak and the cost can be rather expensive as well as they have to be recycled. Even though lithium batteries have to be recycled, they last so much longer.

My source of lithium batteries is often the local computer swap meet. I’ve found that I can usually buy a laptop battery pack quite inexpensively, pull it apart and use the batteries individually or combined in some way. Buying batteries this way can be risky, as you could end up with a lot of exhausted batteries. I’ve been fortunate so far in that I’ve managed to extract just over 50% of good batteries this way.

Gerald the Gorilla

Not the Nine O'clock News - Gerald the Gorilla - The funniest home videos are here

Monday, November 12, 2007

Batteries and MP3 Players

I like to play with Audio, especially cleaning up and creating MP3 songs. The device I use is commonly a Zen player. The sound quality of Zen players is really very good and I prefer to use a Zen rather that an IPod because I dislike the proprietary nature of these devices.

There is however, one major downside to the Zen players that utilize a rechargeable lithium battery. These units require a USB power source with the data lines active, meaning that if you try to charge them with say a USB car charger, the USB connector only has the power lines connected and no data lines. This means that most people will have to buy an expensive charger from Creative, who make the Zen, or use the USB port on their computer. The latter is a very expensive method of charging the Zen player if it requires many hours.

There is however, a very simple and inexpensive workaround. I’ve found if you buy a USB car adapter/charger and a low cost 4-port hub (no power source and even USB 1.0) you can connect the hub to the car charger and then the Zen player to the hub, and it will usually charge the device. I have come across a few hubs that won’t work, so buy locally so you can return the hub for something else. I bought my car chargers from a local computer swap meet and was given some sample hubs for free (maybe because they were USB 1.0).

I’ve gone a stage further and this may also interest MP3 player users who have the type of player that doubles as a memory stick and has the USB connector built-in, which is revealed by removing a cap. These units generally also use a AAA battery and replacing these batteries all the time is frustrating and possibly expensive, as well as polluting the environment.

Using a spare USB car adapter/charger, I took the unit apart and removed the PCB/connector. I also unsoldered and removed the 12-volt spring connections used to make contact in the cigar lighter socket. Using a 4" x 2" x 1.5" plastic box, I cut out slots for the USB connector on the car charger board, and a slide switch for power. I also placed two Li-Ion 18500 Cylindrical Cells (3.7V 2200mAh, approx. 18mm Dia. x 65mm long) in series inside the box. I leave it up to your own creative imagination as to the method of securing these parts (I mainly used hot glue, heavy copper wire and tight fits). I also added a 3.1 mm power socket to charge the 18500 Li-Ion Cells. These Lithium-Ion cells will actually charge up to 4.2 volts, but I generally don’t like going over 4.0 to 4.1 volts so as to extend their life. Two of these cells in series yields just over 8 volts which is enough to still produce the 5 volts at the USB connector, and the cells won’t discharge to below their critical 2.5 volts.

This newly created USB adapter/charger can now serve a number of purposes:

  1. As a Zen charger by using the aforementioned USB hub.
  2. Plugging in a memory-stick type MP3 player without the AAA battery and as soon as power is applied it works just like a player because there are no data lines. This is great for my garage where I leave it on for endless hours.
  3. As a charging device for any other USB charging device such as a cell phone.

The only remaining challenge is a reliable method for charging the two Li-Ion 18500 Cylindrical Cells. I was fortunate to have an 8.4 volt Li-Ion charger, made by Canon for a video camera, but I also have a number of solar panels that will do the job. Without a specialized charger, it is very important not to let the batteries overcharge. A low cost method is to build an electronic timer and a constant current generator—which can even be a low voltage incandescent bulb that can handle 1 or 2 amps placed in series with the Li-Ion batteries and a low voltage DC source.

I've just bought a refurbished Creative MuVo 2GByte MP3 player (for $29 on the Creative site) and this also works with the newly built Li-Ion USB adapter/charger.


Monday, October 29, 2007

Using LED's

I’ve been playing around with LED lighting for years now, getting hold of non-working flash lights, removing the LED’s and using them in a variety of applications. The most common application has been with motion-sensing night-lights. I remove the incandescent bulb and replace it with several LED’s inside a reflctor. I also use NiCad or lithium batteries as the power source.

These days, one can buy LED motion-sensing night-lights, but these use conventional alkaline batteries, such as the Globe LED Motion Activated Locker Light. The cheapest I’ve seen so far are sold at CVS pharmacy for about $7.50. What I do with these lights is that I remove all of the connectors for the batteries, cut out a slot in the top of the battery compartment, and place a couple of flat strips to connect a lithium battery whose dimension is around 47 x 33 x 8 mm. This replaces the three AAA batteries and lasts a lot longer.

Another use I’ve had with LED’s is with the 110v screw-in light bulb replacement. However, these seem to be rather unreliable due to thermal runaway as each LED is wired in series without any current limiter. I’ve actually broken down some of these and re-built them using a plastic funnel and old screw bases. Using my own bridge rectifier and smoothing capacitor helps a little as well as placing two bulbs in series yielding some 60 LED’s is better than a single light with 30 LED’s, a limiting capacitor in series and no smoothing electrolytic capacitor. It’s easy to use two bulbs in series within a couple of hurricane lights that normally use two conventional incandescent lights. This setup uses just over 4 watts of power per lamp, instead of some 60 watts, or 25 watts using florescent lights.

I’ve also placed 5 sets of LED lights within a low level outside wall with each set comprising 4 LED’s in series triggered by a motion sensor and a 12-volt line that is solar powered.

Here's an interesting site that shows how to replace the lithium batteries in a laptop battery pack, something I've done several times.

I've always had an interest in steam locomotives, here is GWR 6024 at Abergavenny.



Monday, October 15, 2007

A La Carte TV?

This topic is an update to one I created a few months ago on a different journal.

I’ve made the decision to cancel my cable TV service because there are too many ads which are too loud, there’s too much paid programming, I can’t select specific channels (a la carte cable) and what I have is very poor variety and quality entertainment—even from over 100 channels!

It seems that an hour of television can carry about twenty minutes or more of commercials. Add on this all those Paid Programming sessions and I’m paying $75 a month to essentially have ads thrown at me. Considering that cable providers interject local ads, I figure that they must be making more than the oil companies.

I plan to make better use of my time and if I want to watch the News, a movie or a documentary, there are plenty of Internet videos to choose from. I’ve noticed that there are a lot of web sites providing World-wide streaming of TV and Radio stations. However, I’m not comfortable with sites that charge a one-time fee as I’ve noticed that they don’t list any channels.

C-Span, Fox News, CNN, BBC and ITV all have a decent amount of news clips. I’ve also been playing with Live-TV and Miro that offers some interesting and easy ways to view video.

Although I have a small Zen Portable Video Player (PVP), it does not have a video-out socket. Rather than continually transferring video through a PVP, I've bought some modern refurbished laptops for $400 each so that I can store and play programs and movies on a TV (using S-Video)--such as this:

The Laptops are Compaq Notebook C500 types and connected wirelessly within a home network.

I've spent a fair amount of time playing with receiving local TV transmissions and I'm amazed at the number of additional channels I can receive with a digital signal. I've placed a simple 7.25-inch ring antenna in the attic, together with a 15Db amplifier (powered by the 12-volt solar/battery line that runs the length of the attic) to supply 4 HDTV's via a 4-way splitter.

I've also discovered a neat program called VEOH which allows me to view and/or store video. The nice thing about this program is that it allows me to to select from a series of videos, and it automatically plays the next in the series.

Check out Zap2it, it's a great TV listing guide.