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dual efie build problem
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dj72amc Offline
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Post: #1
dual efie build problem
Hi Mike,

I just built a single efie using a tamura g509 transformer with your alterations to the eagle research design and now i'm trying to build a dual efie with one tamura g513 trans that has 2 secondary windings. I have only hooked up to one secondary so far and I can't get enough voltage across C3(470uF). I tuned c1 (.56nF) and r2 (22K) to the highest voltage across the g513 secondaries (only about 60mV) and thats with r4 only at 100 ohms and I get 27mV across c3. I took r4 down to 10 ohms but the chip got too hot quick. If I take c3 down to about 200uf will that help? or use the 12v reg instead of the 9v? Or will I have to build it with 2 transformers like the g509? I saw that your dual efie's look like they have 2 transformers but I was hoping to do it with one. If I do have to use two how do they hook to r4? both primaries to r4? or 2 resistors in parallel one to each prim? Any help would be greatly appreciated.

Thanks Dave.
04-07-2008 09:19 AM
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mike Offline
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Post: #2
RE: dual efie build problem
Taking C3 down will not help. You just need to get more juice into the circuit.

I'm surprised that the dual winding Tamura transformer is giving such a poor voltage level. Are the specs on the g513 similar to the g509? I'm looking for similar coil resistances and capacitance. I know when I was looking at Tamura's product list, I chose the g500 for a dual secondary device. I bought one at DigiKey. Both the units I chose have a little more transformer windings than the units you bought. However, you should still be able to get the voltage you need out of them. I can get 5 volts at C3 out of my g508 devices.

I think your dual transformer should work. You'll need pots on the secondary side to adjust the individual circuits. I'm assuming you've tried a few different values for C1? If not, experiment with different values there. I use 10 nF there. I have used 6.8 nF as well. Ok, and here's another thing to try: Put a 15K resistor between pins 6 and 7 of your 555, and 390 ohms between pins 7 & 8 (8 is actually the 9 volt bus). Hopefully you're on a breadboard, and can easily try that out. You might be surprised at the result.

Good luck.

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04-07-2008 03:32 PM
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dj72amc Offline
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Post: #3
RE: dual efie build problem
When I placed my order from digikey they were out of stock on g508's and I didn't check the specs on the others when I ordered. I am using a breadboard for tweeking so changes are simply. I did vary c1 to get as much voltage as I could. I will try your idea about the extra resistors if that doesn't work I will get a g500. I am getting ready to order parts from digikey anyway to build the map sensor enhancer that was posted on the forum. I just got my single efie and hho generator installed on my car, so I'm hoping to see some good mpg gains. This is my first experiment with fuel saver mods.

Thanks for the help, Dave
04-07-2008 06:04 PM
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mike Offline
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RE: dual efie build problem
Lol, I'm afraid I cleared out the inventory at DigiKey of g508s. However, I've been in touch with purchasing, and made them keep some stock on the shelf, and give me MOST of them when I make a big order, but leave some for the guys trying to follow my directions. So there are a few in stock now, and they have more on the way.

Let me know how the resistors work for you. Also, if you get a g500, how that works. I bought one to test, but have never gotten around to testing it yet. I've shifted my dual efie design over to a 556 (dual timer) with separate transformers. This is for maximum stability on both circuits. However, super high stability isn't really important with efies. A 5 or 10 millivolt swing just doesn't matter in the grand scheme of things. However, I want my customers to have the best possible product, and so that's why I made that design decision.

Good luck with your project.

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04-07-2008 08:33 PM
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dj72amc Offline
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Post: #5
RE: dual efie build problem
With the extra resistors the voltage went from 27mV to 165mV so it was a decent increase, but not enough. I just ordered a g500 so I'm going to give that a try. I'll post my results when I get it.
04-08-2008 09:24 AM
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mike Offline
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Post: #6
RE: dual efie build problem
Cool. I'm interested in those results.

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04-08-2008 10:06 AM
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colchiro Offline
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Post: #7
RE: dual efie build problem
555, still helping experimenters build timers for 20 years....Blush

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04-08-2008 12:23 PM
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dj72amc Offline
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Post: #8
dual efie update
I got the dual efie working with the one g513 transformer. The problem was when I switch out the g509 (for my single efie build I still had most of the components wired up on the breadboard) and put the g513 on the breadboard it was only hooked to one side of the bridge rectifier. The leads are configured different on the g513 so i ran jumpers to the rectifier and I was off by a row on the breadboard with one lead. I wired up both secondaries and can get 500 mV no problem out of each side. The only thing is when you adjust one it affects the other. So you can't make adjustments to just one at a time. It will take longer to get it tuned but it does work.
04-12-2008 06:31 PM
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mike Offline
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Post: #9
RE: dual efie build problem
Are you saying that when you adjust the DC part of the circuit it affects the other DC voltage? It would have to cause this affect through both bridge rectifiers. But is that what you're experiencing?

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04-12-2008 07:26 PM
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dj72amc Offline
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Post: #10
RE: dual efie build problem
Increasing one side also increased the other side about 50% as much. So say side A was 300mV and side B was 200mV. If you wanted to increase side A to 350mV and keep side B 200mV you would have to increase the trim pot(r6 on eagle research design) on side A and decrease the trim pot on side B. It will make it a pain to fine tune but it works.
04-12-2008 08:12 PM
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