Basics Home Power, We have a few questions and would appreciate any info you might have: -a good book on basic electronics -a plan to build a regulated power supply that utilizes 12 volts DC from the battery bank and has an output of approximately 0 to 20 volts DC and 0 to 5 amps. Again, we think your magazine and philosophy is terrific! Allen and Renee' Cook, Bozeman, MT I am hard put to give you the title of one good basic book on electronics. I didn't learn from a book, but from a breadboard and a pile of parts. Any high school Physics book will deliver the science you need to work the wonders of electronics. As to the specifics of circuit design, there are hundreds of books each about a special facet of this enormous area. Here's my favorite: Electronic Design With Off-The-Shelf Integrated Circuits by Meiksin and Thackray (Parker Publishing Co.). Also good is ANYTHING written by Forrest Mimms. The manuals used by the US Air Force and US Army are simple, straight-forward and strictly functional- they teach quickly and well. I have no specific plans for the power supply you mentioned, but several companies produce DC/DC converters that will do as you wish (for example,. Tamura, 1150 Dominguez St., Carson, CA 90746 213-638-1790 or Abbott Transistor Labs, 2721 S. La Cienega Blvd., Los Angles, CA 90034 213-202-8820. Richard Crying Radio Karen Perez; Please renew our subscription for three more years. Your magazine is the most informative for those of us AE people in the USA and the world. Keep up the good work - Peace - Love - Harmony to you all. Two questions. When listening to AM radio and a fluorescent light is turned on, what causes the radio to make that strange crying noise? How can it be eliminated other than turning the light or radio off? Thank you. David Benedict, Native Self-Sufficiency Center, RD1 Box 375 Coldbrook, NY 13324 There is no simple, sure fix. What you are hearing on the radio is radio frequency interference (RFI) emitted by the fluorescent light. If the light and radio are powered on DC directly from the battery, then use capacitors to filter out the noise. Add a .001f capacitor across the power leads at the battery and another at the light. Or use coaxial cable for the light's power wiring, and still add both capacitors. Or use an incandescent lamp (all incandescents are RFI quiet) if all the above fails. If the light and the radio are powered by the same inverter, then the situation is entirely more sticky. In this case, try every sort of 120 vac interference and noise filter you can get your hands on. Most won't totally silence the light. If you are really into noise-free radio, shut off the inverter and all fluorescent lights (either DC or ac), and listen. The inverter or fluorescent that is totally RFI quiet has yet to be invented. Richard Interfering Inverter Dear Home Power, I'd like to know if there is anyone out there who has knowledge of inverter interference with telephone lines. We have a Power Pal 1200 watt inverter and it seems when it is on there is a definite static on our phone line. I'm wondering if other Power Pal users have had this experience, and if any other inverters have presented similar problems to users. I'm also wondering if this interference could pose a problem with modem communication? Right now I have the use of an Apple IIe with modem. I don't seem to have any problem communicating with MCI mail; but when I try to directly communicate to someone in Spokane with an IBM system, I received a line but was sending gibberish. Now I suppose the problem here could lie in not having exactly the right set up between us. I wondered if the inverter could be the culprit, as it must be on to run my system. Any info would be appreciated. Our family enjoys your magazine immensely. We are off grid and totally solar powered here in the land of sunshine in Eastern Washington. Long live Mother Earth, Terri Reed, RT3 Box 72-R, Davenport, WA 99122 Hi, Terri. Your problem is very common to many inverter users. The problem is that the modified-sine wave of the inverter is being coupled to the telephone wiring. The interference is creeping in where the 120 vac power wiring and the telephone wiring are close together. Rerouting of your phone wiring will most certainly stop the problem. Avoid running the phone and power wiring parallel to each other and within 24 inches of each other. If a phone line must cross a power wire, then let it cross at right angles and proceed perpendicular for at least two feet before turning parallel. Consider that your power wires are broadcasting antennas and your phone wires are receiving antennas. Do your best to see that these antennas talk to each other as little as possible. The best fix is to increase the physical distance between power and phone wiring. The problem with data transfer sounds to me like protocol problems (software smtz) and not line noise. In general modems will function on very noisy lines. Richard. Solar Food Dryer In reference to the letter from Pat Lambert in HP#22, Pat and other Home Power people may like to know a few sources for plans for solar food dryers. The January 1979 issue of Popular Mechanics had an article entitled "Build PM's Solar Food Dryer" with complete plans and a few references. In 1981 Rodale Press, 33 E. Minor St., Emmaus, PA 18049, published a book, Solar Food Dryer, ISBN 0-87857-333-X. Included were very complete plans and instructions for drying foods. Probably out of print, but library may help. Undoubtably there are other sources for plans also. Does take a bit of digging. Bear, Bodega, CA Thanks again, Bear. This comes just in time to get one built before the crops are ripe. - KJS EDTA Report Last year I purchased a used mini-motorhome. It is parked 51 weeks out of the year - and when I used it I found the aux battery that powers the interior lights, pump, etc. when motor is off, would power things for up to four hours, but the next morning had lost its charge completely. Before a short trip I planned to fill it with EDTA dissolved in water but when opening the battery found all cells completely full, so I put in about 1/2 tsp. per cell powdered EDTA on the tip of a butter knife dipped into the bag. After driving about 150 miles I camped for the night - next morning the battery powered lights and pump. Returning home the camper is parked - 3 days later the aux battery will run the lights but not quite enough power to run the pump. Next time I use it I will put in more EDTA. I imagine battery was empty and was filled just before I bought it. Question: On "zapping" Ni-Cad batteries - I have several square Ni-Cads out of rechargable lights - Hitachi HP21 - 6 (6MI.2) and Panasonic LCR6 (rest obscured) 7.3-7.5V/20 hr. battery - can they be "zapped" - and please give exact instructions to zap off of 12V battery! Thank you. Pat Weissleader, Desert Hot Springs, CA You can zap these packs. Be careful, wear glasses and gloves. Hook up a 14 ga. wire between the negative pole of the 12 Volt battery and the negative pole of the nicad pack. Hook up a similar wire to the positive pole of the 12 Volt battery and VERY GENTLY AND VERY QUICKLY brush this wire's end across the positive terminal of the nicad pack. You will see a large spark and feel the nicad pack get warm. You have just zapped about a hundred of Amperes of current into the nicad for a very short (less than 1/2 second) period of time. This zap of high current vaporizes the dendrites that tend to form within sintered plate nicads and create shorts. It also heats the hell out of the nicad and can damage or even explode the cell if zap too often or for too long a period. So give the nicads the shortest possible zap and let them rest for at least 24 hours before zapping again. If the nicad doesn't respond to two of these zap regimes, then the battery has problems that cannot solved by massive doses of high current. Such is life... Richard. Low Head Good Morning! We currently live in an old building whose electrical power is supplied entirely by the local commercial electric utility. We must replace this and plan to begin building a new home this summer. Our plans include alternative energy and we need help and information about options viable in out situation. Our building site lies next to one of our three spring-fed ponds. The water flow is approximately 85-90 gallons/minute and the drop is one foot. Our research of water power leads us to conclude that the drop is insufficient, yet the flow is adequate. Is water power an option for us? Any suggestions? Any back issues of your magazine that address water power variables? We appreciate any additional help and information you may have! Thank you. Wendy Koljord & Ralph Zerbe, RR1 Box 144, Houston, MN 55943 I refer you to the low head hydro article in this issue. Good luck. -KJS You have a fair amount of water, but 12 inches of head is low even from the low head systems on page 6 of this issue. Talk to Cameron McLeod and ask him if he can build ultra low head machines that produce say a hundred Watts instead of a thousand Watts. Richard Picture Perfect I'm trying to conduct a photography (landscape and wildlife) business here from my AE home. I've had much success and some frustrations, i.e. my Beseler Duel Dichro Color Head on my 120V enlarger blows the 24V 250W quartz halogen bulb every time I try to run it on my Trace 2012 inverter. Trace has suggested a pure sine wave filter (transformer). I'd like to hear from other running businesses on AE power, especially those utilizing sensitive electronics. Anyone have any experience with pure sine wave filters? At $250 for a 250W model I'm reluctant to experiment! John Senser, 16000 Old Oak Ranch Rd., Sonora, CA 95370 Your problem lies in the power supply in the enlarger. This supply makes 24 VDC from the incoming 120 vac from the inverter. I'll bet dollars to donuts that this supply is not regulated. Any techie work his salt can either regulate this supply, or reduce its output via a series resistor, or limit its starting surge via a thermistor (see Jim Forgette's Homebrew in this issue.) The sine wave filter may work, and then again it may not, I have not direct experience with this enlarger. How about readers? Help this fellow out and he may send you a ultrafine photo! Richard. Cheap PVs? In response to dozens of letters from readers, I did some research into the new PV making process recently revealed by Texas Instruments. Here's what I found out... Texas Instruments (TI) and Southern California Edison (SCE) recently announced a new photovoltaic manufacturing process that could make PVs America's favorite form of roofing. TI's Spheral Solar cell is billed as an extremely simple, low-tech process with about an 8 to 10% conversion efficiency. The cells are made using approximately 17,000 spheres of low-purity, metallurgical-grade silicon, bonded in round holes in a 100 mm x 100 mm square of aluminum foil. During the process impurities in the silicon are pushed to the surface. Sphere formation is done in a furnace and uses surface tension phenomenon. Impurities are etched from the surface of each sphere. An aluminum sheet is embedded and etched into a wire frame and the spheres are bonded to it with a heat/pressure bond. An insulator and another sheet of aluminum with no holes is applied, so that each sphere becomes a p-n junction between the two layers. The cell is flexible and should be extremely robust. If any individual sphere fails, the output of the cell only diminishes by 1/17,000th. Over the last six years TI and SCE have each contributed $5 million toward development costs. Prototypes of the Spheral Solar cell are fully functional. Field tests are scheduled for late 1991. If a viable manufacturing process can be developed, PVs could drop from an average $8 per watt (25-30 per kilowatt hour) to as low $1.50 to $2.00 per watt (10-20 per kilowatt hour). If all goes well, Spheral Solar cells could be available by the first part of 1995. Karen Perez Access: Texas Instruments Inc., Materials and Controls Group, 1-800-336-5236, Ext. 700 (PV-91001). Southern California Edison, Action Line, 1-800-952-5062