Created Oct 2007 NOTE: Reading through the D9.PDF I have come to some conclusions. These are Not Necessarily in any order, but will hopefully give some insight of the problems involved. Also Some Quote From Bob Boyce that will interest you:
First, I read somewhere that Bob uses a 1000 watt inverter and it is putting out about 6 amps at 110 volts. That is 660 watts at 100% efficiency. With a 80-90% efficiency, This will relate to about 65 amps from your 12 volt battery. THATS A LOT OF CURRENT. And even using just straight DC Electrolysis with 65 Amps at 12 volts in any cell will produce substantial gas. If this is true, be prepared to add a Second car battery and Alternator to run this system. Or at least a Much Higher Current One, If you can fit one onto your car. At BEST, An alternator should NOT be expected to put out more than "70% of rated current for Continuous Duty". (NOTE: Most Factory Alternators are rated between 60 to 90 amps.) And thats Only if you can Keep it Cool. Considering a Hot Day, An even More Practical figure would be 50%.
A Quote From Bob Boyce on OUPower. Posted: Fri Oct 05, 2007 11:54 am Bob Boyce Regular Poster Joined: 23 Jan 2005 Posts: 818 Location: Eastern TN Hello Gary, Yes, I do remember when you mentioned that. It was good advice for people to follow. I found it was a necessary change when testing a new batch of 556 chips that arrived last week. I complained about those bad batches to TI, and they shipped me out some samples of their current source 556 chips. The new batch tested good to go and met spec just fine, so I ordered 100 from Digi-Key. When they arrived, they were all of the new source. The cap changes did bring the desired frequencies closer to the center tuning range of the potentiometers with these new chips. Also, I did try those Tiawan and unmarked origin TI chips with the new value caps, and they still did not operate above, or even near the 40 Khz region. They still cut out when trying to tune up. I had already tried changing timing resistors and timing cap changes with them, and they just failed to reach 40 Khz regardless. Oh, I added bypass caps to the chips on a couple of assembled and tested PWM3F boards, and measured rail noise before and after. It made no discernable difference, nor did it allow those bad batch 556 chips to operate at higher frequencies. I do agree that the bypass caps should be there, but they were not the cause of the problem with the bad batches of 556 timer chips. The other changes I made (the resistors) were done only to crispen up the FET response a bit. For fear of failure in adverse tuning conditions (such as improper tuning by newbies), I was not loading the OCP-PCP116 chips much. Now they are operating closer to the maximum ratings, but they can also now be destroyed by careless tuning. The devices are rated for 50 mA average, with 1 A peaks. The board works either way, but with the changes it does allow for more energy tapping at less input power. All of these changes were made to improve operation of existing PWM3E and PWM3F boards, if so desired, and so that new builders have the option to make the changes if they want. It will be the last support change made for the PWM3E and PWM3F revision boards. It's just not worth all the headaches to me to deal with what I consider an obsolete design. Now I have a couple of assembled and tested PWM3F boards to get rid of, as I do not use these any more myself. Bob In Another post I saw Elsewhere, Sorry but can't Find it now: Bob said: The PWM3 was only designed for use on the Bench. "It it is Not Practical for use in a Vehicle". SO WHY WOULD YOU BUILD IT?
Quoting Page 28 of One of the D9 Pdf's: (NOTE: There have been MANY Different D9 PDF's created and revised.) The exact details of the primary windings from the operational characteristics of the cells. This means you must build, cleanse and condition your cells prior to making the operational measurements. From those measurements, calculations can be made to determine what gauge and how many turns of solid-core, silver-plated, teflon-insulated, copper wire are to be used for each of the three primary windings. "And More in the next paragraphs, which you can read for yourself in the D9 PDF". My Opinions: While Teflon wire May be useful in Reducing "Interwire Capacitance" on these windings, I see absolutely no need for the Silver-Plated wire. If this is just to reduce the Resistance, "increasing the wire gauge up one AWG" should accomplish the same thing and cost you much less money. ** I also phoned a friend of mine who is a "Transformer Design Engineer" and he varified both my conclusions above. Further, This D9 PDf says: QUOTE: "The Torroid Secondary should be about 140 Turns of 16 AWG solid-core, silver-plated, teflon-insulated wire". It than gives two different operations: a) Using an Inverter with 155 volts DC. b) Just using the 13.8 Volts, Running Voltage from your battery: In (a) above, it would appear your torroid would require 542 Turns of wire on EACH Primary to Output only 40 volts. And I doubt there is room for that much wire. But WHY 40 Volts? Previously on page 17, he says: a 100 plate cell with 1.5 volts per cell. ** Sorry, Am I Misreading something? In (b) Above it requires an increase to 40 volts. Still, WHY 40 Volts? ** Sorry but this makes No Sense to me. Now, as to Wire Gauges: Based on "700 circular Mils per ampere", An 18 AWG Gauge Copper wire (1624 Circular Mils) is capable of handling only 2.32 amps continuously. NOTE: 700 Circular Mils is quite Standard for transformer designs. Using a lower value of say "500 Circular Mils" will create Excessive Heating in the transformer and would give you 3.25 amps. I have No Idea how Bob Boyce determines that this setup can possibly produce the High Power Output he claims. From what I can see, the Output will be LESS than the Input. Some Additional Facts and Explainations: Note-1: According to the wire charts, a Single 18 AWG wire in Open Air can handle up to 16 amps with a Maximum Ambient Temperature of 135 degree and a Maximum Wire temperature of 212 degrees. Note-2: According to the wire charts, an 18 AWG wire in a Bundle or in Conduits can handle up to 10 amps with a Maximum Ambient Temperature of 135 degree and a Maximum Wire temperature of 212 degrees. Now the "Main Advantage of a Torroid Core", Unlike Other Cores, is the Wire can be spread out over the entire diameter of the core. So, when Wound on a SINGLE LAYER, Radiation of the Heat is Greater, so this allows for Higher Currents to be used without excessive heating. However in "Bob Boyce's Torroid", While he is using a Single layer for the Secondary, He has wound the Primary's Over the Seconday, and this no longer allows for the cooling as would be the case of a single layer.