T&L Publications

For the electric rates and day/night, seasonal, or whatever depends on the area you live. Here in southern France, electricity is about 0.07 Euro/kwh during the day and about 0.04 at night (11pm to 7am). The meters are electronic and switch between the two rates. The bill then shows day usage and ni...

Are you trying to measure RPM based on the ripple in the output voltage? Are you wanting alternator RPM or are you trying to measure engine RPM (or whatever is driving the alternator)? How about something to mark the pulley and using an optical tach setup? Anyway, give specifics of what you are tryi...

Hi Al, Yes, the 7805 supplies the 5v. There is a 0.1uF cap on the output and I have been experimenting with input capacitor value. The datasheet recommends 0.33uF, so that is what I will probably stick with. I reduced R3 to 10k and ran another wire directly from the 7805 tab to the back of the coil....

Thanks for the reply, Al. I think the pulse is because of the way it is wired. I do have a wire that runs from the circuit (connects to the center pin on the 7805 and to the tab) and connects to the back of the coil pack. The power supply - is also connected to the same point. I will run an addition...

I mean from the back of the coil pack (ground of the coil) to the ground tab on the 7805 voltage regulator. What I am trying to do is the following: -take an input from the factory igniton system (open collector, normally sits at battery voltage, pulls to ground when charging coil) - basically inver...

Here you go. Top trace is input, bottom is output. Top is 5V/div, bottom is 2V/div. Time base is 2ms/div No coil connected. http://img216.imageshack.us/img216/2103/p10100142pb.th.jpg Coil connected http://img137.imageshack.us/img137/5283/p10100154lt.th.jpg Ground, 0.1V/div Time base same as above. V...

Sure. I will post a pic here in a few minutes. The "IN" looks pretty good to me, but I could be wrong.

I was thinking of using a ferrite bead. Not sure what one to use exactly. The noise is at the frequency of the sparking (~20Hz (idle) to 300Hz or so at high RPM). It may be a bit difficult as the frequency is fairly low. The amplitude I am seeing is about 0.2v or so. Perhaps it would be better using...

Hi all, Following up on this. I finally got an o-scope here to mess around with this circuit. I added a capacitor to the input on the 7805 and that cleaned up the noise on the waveform a lot. I am experimenting with bypass caps. What do you recommend? 0.1uF? Tantalum, disc, .. ? It seems as most of ...

Hi, You can check the computer PS for a rating. It will usually say: 12v x.x amp -12v x.x amp 5v x.x amp You will have to see if the PS is up to the task, first. If you do run 6 sets of 3, why not run a fuse in series with each set if you are worried. You are drawing ~1amp on each line, so maybe a 1...

Thanks, Al. I have a single 0.1uF cap going between 5v (next to the v-reg) and ground. Do you think I need more than this? The board is quite small (~2"x2"). RF is something I have been thinking. Basically the difference between the coil connected and not is: - increased load on the circui...

Thanks. Which pic are you referring to (one that I posted or one in the link)? There are 2 problems (probably related): - under certain frequencies, there is a second waveform on top of the input/output signals when the signals are in the high state. - some conditions with the coil connected causes ...

Thanks, Stephen. That makes sense. The supply voltage shouldn't drop that low as it is supplied from the car battery (~14v running, 12.8v engine off). I will take a look at that too to be sure. Any ideas are welcomed and appreciated. I will let you know what we find out.

Kent

Thanks, Stephen. We will have a look. I have a 0.1uF cap between 5v and ground. Do you think I need another cap on the input (~12v and ground)? The input impedance of the ignitor/coil pack is about 1.1kOhm (DC). So the circuit only needs to source less than 5mA with the coil connected. Another possi...

Okay, guys. I have a little more information now. A couple friend in Australia are doing some testing of the circuit. On the bench, the circuit works just as it is supposed to and with no delay that would cause the timing issues the guys were seeing earlier. When the coil/ignitor is connected, it ap...